diff --git a/lib/jasmine-core/jasmine.js b/lib/jasmine-core/jasmine.js
index e058f6a5..f2ebfa23 100644
--- a/lib/jasmine-core/jasmine.js
+++ b/lib/jasmine-core/jasmine.js
@@ -100,6 +100,7 @@ var getJasmineRequireObj = (function(jasmineGlobal) {
     j$.StringContaining = jRequire.StringContaining(j$);
     j$.UserContext = jRequire.UserContext(j$);
     j$.Suite = jRequire.Suite(j$);
+    j$.SuiteBuilder = jRequire.SuiteBuilder(j$);
     j$.Timer = jRequire.Timer();
     j$.TreeProcessor = jRequire.TreeProcessor();
     j$.version = jRequire.version();
@@ -1100,8 +1101,6 @@ getJasmineRequireObj().Env = function(j$) {
     const self = this;
     const global = options.global || j$.getGlobal();
 
-    let totalSpecsDefined = 0;
-
     const realSetTimeout = global.setTimeout;
     const realClearTimeout = global.clearTimeout;
     const clearStack = j$.getClearStack(global);
@@ -1118,14 +1117,11 @@ getJasmineRequireObj().Env = function(j$) {
       return r ? r.id : null;
     });
 
-    let topSuite;
     let currentSpec = null;
     const currentlyExecutingSuites = [];
-    const focusedRunables = [];
-    let currentDeclarationSuite = null;
     let hasFailures = false;
-    let deprecator;
     let reporter;
+    let topSuite;
 
     /**
      * This represents the available options to configure Jasmine.
@@ -1345,18 +1341,6 @@ getJasmineRequireObj().Env = function(j$) {
     j$.Expectation.addCoreMatchers(j$.matchers);
     j$.Expectation.addAsyncCoreMatchers(j$.asyncMatchers);
 
-    let nextSpecId = 0;
-
-    function getNextSpecId() {
-      return 'spec' + nextSpecId++;
-    }
-
-    let nextSuiteId = 0;
-
-    function getNextSuiteId() {
-      return 'suite' + nextSuiteId++;
-    }
-
     const expectationFactory = function(actual, spec) {
       return j$.Expectation.factory({
         matchersUtil: runableResources.makeMatchersUtil(),
@@ -1450,43 +1434,6 @@ getJasmineRequireObj().Env = function(j$) {
         return spec.addExpectationResult(passed, result);
       }
     };
-    const suiteAsyncExpectationFactory = function(actual, suite) {
-      return asyncExpectationFactory(actual, suite, 'Suite');
-    };
-
-    const specAsyncExpectationFactory = function(actual, suite) {
-      return asyncExpectationFactory(actual, suite, 'Spec');
-    };
-
-    function beforeAndAfterFns(targetSuite) {
-      return function() {
-        let befores = [],
-          afters = [],
-          suite = targetSuite;
-
-        while (suite) {
-          befores = befores.concat(suite.beforeFns);
-          afters = afters.concat(suite.afterFns);
-
-          suite = suite.parentSuite;
-        }
-
-        return {
-          befores: befores.reverse(),
-          afters: afters
-        };
-      };
-    }
-
-    function getSpecName(spec, suite) {
-      const fullName = [spec.description],
-        suiteFullName = suite.getFullName();
-
-      if (suiteFullName !== '') {
-        fullName.unshift(suiteFullName);
-      }
-      return fullName.join(' ');
-    }
 
     /**
      * Causes a deprecation warning to be logged to the console and reported to
@@ -1548,16 +1495,17 @@ getJasmineRequireObj().Env = function(j$) {
       new j$.QueueRunner(options).execute(args);
     }
 
-    topSuite = new j$.Suite({
-      id: getNextSuiteId(),
-      description: 'Jasmine__TopLevel__Suite',
-      expectationFactory: expectationFactory,
-      asyncExpectationFactory: suiteAsyncExpectationFactory,
-      autoCleanClosures: config.autoCleanClosures,
-      onLateError: recordLateError
+    const suiteBuilder = new j$.SuiteBuilder({
+      env: this,
+      expectationFactory,
+      asyncExpectationFactory,
+      onLateError: recordLateError,
+      specResultCallback,
+      specStarted,
+      queueRunnerFactory
     });
-    deprecator = new j$.Deprecator(topSuite);
-    currentDeclarationSuite = topSuite;
+    topSuite = suiteBuilder.topSuite;
+    const deprecator = new j$.Deprecator(topSuite);
 
     /**
      * Provides the root suite, through which all suites and specs can be
@@ -1687,8 +1635,8 @@ getJasmineRequireObj().Env = function(j$) {
       installGlobalErrors();
 
       if (!runablesToRun) {
-        if (focusedRunables.length) {
-          runablesToRun = focusedRunables;
+        if (suiteBuilder.focusedRunables.length) {
+          runablesToRun = suiteBuilder.focusedRunables;
         } else {
           runablesToRun = [topSuite.id];
         }
@@ -1768,7 +1716,7 @@ getJasmineRequireObj().Env = function(j$) {
          */
         reporter.jasmineStarted(
           {
-            totalSpecsDefined: totalSpecsDefined,
+            totalSpecsDefined: suiteBuilder.totalSpecsDefined,
             order: order
           },
           function() {
@@ -1789,10 +1737,10 @@ getJasmineRequireObj().Env = function(j$) {
                   topSuite.result.failedExpectations.length > 0
                 ) {
                   overallStatus = 'failed';
-                } else if (focusedRunables.length > 0) {
+                } else if (suiteBuilder.focusedRunables.length > 0) {
                   overallStatus = 'incomplete';
                   incompleteReason = 'fit() or fdescribe() was found';
-                } else if (totalSpecsDefined === 0) {
+                } else if (suiteBuilder.totalSpecsDefined === 0) {
                   overallStatus = 'incomplete';
                   incompleteReason = 'No specs found';
                 } else {
@@ -1950,22 +1898,6 @@ getJasmineRequireObj().Env = function(j$) {
       );
     };
 
-    function ensureIsFunction(fn, caller) {
-      if (!j$.isFunction_(fn)) {
-        throw new Error(
-          caller + ' expects a function argument; received ' + j$.getType_(fn)
-        );
-      }
-    }
-
-    function ensureIsFunctionOrAsync(fn, caller) {
-      if (!j$.isFunction_(fn) && !j$.isAsyncFunction_(fn)) {
-        throw new Error(
-          caller + ' expects a function argument; received ' + j$.getType_(fn)
-        );
-      }
-    }
-
     function ensureIsNotNested(method) {
       const runable = currentRunable();
       if (runable !== null && runable !== undefined) {
@@ -1975,150 +1907,38 @@ getJasmineRequireObj().Env = function(j$) {
       }
     }
 
-    function suiteFactory(description) {
-      return new j$.Suite({
-        id: getNextSuiteId(),
-        description: description,
-        parentSuite: currentDeclarationSuite,
-        timer: new j$.Timer(),
-        expectationFactory: expectationFactory,
-        asyncExpectationFactory: suiteAsyncExpectationFactory,
-        throwOnExpectationFailure: config.stopSpecOnExpectationFailure,
-        autoCleanClosures: config.autoCleanClosures,
-        onLateError: recordLateError
-      });
-    }
-
-    this.describe = function(description, specDefinitions) {
+    this.describe = function(description, definitionFn) {
       ensureIsNotNested('describe');
-      ensureIsFunction(specDefinitions, 'describe');
-      const suite = suiteFactory(description);
-      if (specDefinitions.length > 0) {
-        throw new Error('describe does not expect any arguments');
-      }
-      if (currentDeclarationSuite.markedExcluding) {
-        suite.exclude();
-      }
-      addSpecsToSuite(suite, specDefinitions);
-      if (suite.parentSuite && !suite.children.length) {
-        throw new Error(
-          'describe with no children (describe() or it()): ' +
-            suite.getFullName()
-        );
-      }
-      return suite.metadata;
+      return suiteBuilder.describe(description, definitionFn).metadata;
     };
 
-    this.xdescribe = function(description, specDefinitions) {
+    this.xdescribe = function(description, definitionFn) {
       ensureIsNotNested('xdescribe');
-      ensureIsFunction(specDefinitions, 'xdescribe');
-      const suite = suiteFactory(description);
-      suite.exclude();
-      addSpecsToSuite(suite, specDefinitions);
-      return suite.metadata;
+      return suiteBuilder.xdescribe(description, definitionFn).metadata;
     };
 
-    this.fdescribe = function(description, specDefinitions) {
+    this.fdescribe = function(description, definitionFn) {
       ensureIsNotNested('fdescribe');
-      ensureIsFunction(specDefinitions, 'fdescribe');
-      const suite = suiteFactory(description);
-      suite.isFocused = true;
-
-      focusedRunables.push(suite.id);
-      unfocusAncestor();
-      addSpecsToSuite(suite, specDefinitions);
-
-      return suite.metadata;
+      return suiteBuilder.fdescribe(description, definitionFn).metadata;
     };
 
-    function addSpecsToSuite(suite, specDefinitions) {
-      const parentSuite = currentDeclarationSuite;
-      parentSuite.addChild(suite);
-      currentDeclarationSuite = suite;
+    function specResultCallback(spec, result, next) {
+      runableResources.clearForRunable(spec.id);
+      currentSpec = null;
 
-      let declarationError = null;
-      try {
-        specDefinitions();
-      } catch (e) {
-        declarationError = e;
+      if (result.status === 'failed') {
+        hasFailures = true;
       }
 
-      if (declarationError) {
-        suite.handleException(declarationError);
-      }
-
-      currentDeclarationSuite = parentSuite;
+      reportSpecDone(spec, result, next);
     }
 
-    function findFocusedAncestor(suite) {
-      while (suite) {
-        if (suite.isFocused) {
-          return suite.id;
-        }
-        suite = suite.parentSuite;
-      }
-
-      return null;
+    function specStarted(spec, suite, next) {
+      currentSpec = spec;
+      runableResources.initForRunable(spec.id, suite.id);
+      reporter.specStarted(spec.result, next);
     }
 
-    function unfocusAncestor() {
-      const focusedAncestor = findFocusedAncestor(currentDeclarationSuite);
-      if (focusedAncestor) {
-        for (let i = 0; i < focusedRunables.length; i++) {
-          if (focusedRunables[i] === focusedAncestor) {
-            focusedRunables.splice(i, 1);
-            break;
-          }
-        }
-      }
-    }
-
-    const specFactory = function(description, fn, suite, timeout) {
-      totalSpecsDefined++;
-      const spec = new j$.Spec({
-        id: getNextSpecId(),
-        beforeAndAfterFns: beforeAndAfterFns(suite),
-        expectationFactory: expectationFactory,
-        asyncExpectationFactory: specAsyncExpectationFactory,
-        onLateError: recordLateError,
-        resultCallback: specResultCallback,
-        getSpecName: function(spec) {
-          return getSpecName(spec, suite);
-        },
-        onStart: specStarted,
-        description: description,
-        queueRunnerFactory: queueRunnerFactory,
-        userContext: function() {
-          return suite.clonedSharedUserContext();
-        },
-        queueableFn: {
-          fn: fn,
-          timeout: timeout || 0
-        },
-        throwOnExpectationFailure: config.stopSpecOnExpectationFailure,
-        autoCleanClosures: config.autoCleanClosures,
-        timer: new j$.Timer()
-      });
-      return spec;
-
-      function specResultCallback(result, next) {
-        runableResources.clearForRunable(spec.id);
-        currentSpec = null;
-
-        if (result.status === 'failed') {
-          hasFailures = true;
-        }
-
-        reportSpecDone(spec, result, next);
-      }
-
-      function specStarted(spec, next) {
-        currentSpec = spec;
-        runableResources.initForRunable(spec.id, suite.id);
-        reporter.specStarted(spec.result, next);
-      }
-    };
-
     function reportSpecDone(spec, result, next) {
       spec.reportedDone = true;
       reporter.specDone(result, next);
@@ -2129,66 +1949,19 @@ getJasmineRequireObj().Env = function(j$) {
       reporter.suiteDone(result, next);
     }
 
-    this.it_ = function(description, fn, timeout) {
-      ensureIsNotNested('it');
-      // it() sometimes doesn't have a fn argument, so only check the type if
-      // it's given.
-      if (arguments.length > 1 && typeof fn !== 'undefined') {
-        ensureIsFunctionOrAsync(fn, 'it');
-      }
-
-      if (timeout) {
-        j$.util.validateTimeout(timeout);
-      }
-
-      const spec = specFactory(
-        description,
-        fn,
-        currentDeclarationSuite,
-        timeout
-      );
-      if (currentDeclarationSuite.markedExcluding) {
-        spec.exclude();
-      }
-      currentDeclarationSuite.addChild(spec);
-
-      return spec;
-    };
-
     this.it = function(description, fn, timeout) {
-      const spec = this.it_(description, fn, timeout);
-      return spec.metadata;
+      ensureIsNotNested('it');
+      return suiteBuilder.it(description, fn, timeout).metadata;
     };
 
     this.xit = function(description, fn, timeout) {
       ensureIsNotNested('xit');
-      // xit(), like it(), doesn't always have a fn argument, so only check the
-      // type when needed.
-      if (arguments.length > 1 && typeof fn !== 'undefined') {
-        ensureIsFunctionOrAsync(fn, 'xit');
-      }
-      const spec = this.it_.apply(this, arguments);
-      spec.exclude('Temporarily disabled with xit');
-      return spec.metadata;
+      return suiteBuilder.xit(description, fn, timeout).metadata;
     };
 
     this.fit = function(description, fn, timeout) {
       ensureIsNotNested('fit');
-      ensureIsFunctionOrAsync(fn, 'fit');
-
-      if (timeout) {
-        j$.util.validateTimeout(timeout);
-      }
-      const spec = specFactory(
-        description,
-        fn,
-        currentDeclarationSuite,
-        timeout
-      );
-      currentDeclarationSuite.addChild(spec);
-      focusedRunables.push(spec.id);
-      unfocusAncestor();
-      return spec.metadata;
+      return suiteBuilder.fit(description, fn, timeout).metadata;
     };
 
     /**
@@ -2257,59 +2030,22 @@ getJasmineRequireObj().Env = function(j$) {
 
     this.beforeEach = function(beforeEachFunction, timeout) {
       ensureIsNotNested('beforeEach');
-      ensureIsFunctionOrAsync(beforeEachFunction, 'beforeEach');
-
-      if (timeout) {
-        j$.util.validateTimeout(timeout);
-      }
-
-      currentDeclarationSuite.beforeEach({
-        fn: beforeEachFunction,
-        timeout: timeout || 0
-      });
+      suiteBuilder.beforeEach(beforeEachFunction, timeout);
     };
 
     this.beforeAll = function(beforeAllFunction, timeout) {
       ensureIsNotNested('beforeAll');
-      ensureIsFunctionOrAsync(beforeAllFunction, 'beforeAll');
-
-      if (timeout) {
-        j$.util.validateTimeout(timeout);
-      }
-
-      currentDeclarationSuite.beforeAll({
-        fn: beforeAllFunction,
-        timeout: timeout || 0
-      });
+      suiteBuilder.beforeAll(beforeAllFunction, timeout);
     };
 
     this.afterEach = function(afterEachFunction, timeout) {
       ensureIsNotNested('afterEach');
-      ensureIsFunctionOrAsync(afterEachFunction, 'afterEach');
-
-      if (timeout) {
-        j$.util.validateTimeout(timeout);
-      }
-
-      afterEachFunction.isCleanup = true;
-      currentDeclarationSuite.afterEach({
-        fn: afterEachFunction,
-        timeout: timeout || 0
-      });
+      suiteBuilder.afterEach(afterEachFunction, timeout);
     };
 
     this.afterAll = function(afterAllFunction, timeout) {
       ensureIsNotNested('afterAll');
-      ensureIsFunctionOrAsync(afterAllFunction, 'afterAll');
-
-      if (timeout) {
-        j$.util.validateTimeout(timeout);
-      }
-
-      currentDeclarationSuite.afterAll({
-        fn: afterAllFunction,
-        timeout: timeout || 0
-      });
+      suiteBuilder.afterAll(afterAllFunction, timeout);
     };
 
     this.pending = function(message) {
@@ -9899,6 +9635,311 @@ getJasmineRequireObj().Suite = function(j$) {
   return Suite;
 };
 
+getJasmineRequireObj().SuiteBuilder = function(j$) {
+  class SuiteBuilder {
+    constructor(options) {
+      this.env_ = options.env;
+      this.expectationFactory_ = options.expectationFactory;
+      this.suiteAsyncExpectationFactory_ = function(actual, suite) {
+        return options.asyncExpectationFactory(actual, suite, 'Suite');
+      };
+      this.specAsyncExpectationFactory_ = function(actual, suite) {
+        return options.asyncExpectationFactory(actual, suite, 'Spec');
+      };
+      this.onLateError_ = options.onLateError;
+      this.specResultCallback_ = options.specResultCallback;
+      this.specStarted_ = options.specStarted;
+      this.queueRunnerFactory_ = options.queueRunnerFactory;
+
+      this.nextSuiteId_ = 0;
+      this.nextSpecId_ = 0;
+
+      this.topSuite = this.suiteFactory_('Jasmine__TopLevel__Suite');
+      this.currentDeclarationSuite_ = this.topSuite;
+      this.totalSpecsDefined = 0;
+      this.focusedRunables = [];
+    }
+
+    describe(description, definitionFn) {
+      ensureIsFunction(definitionFn, 'describe');
+      const suite = this.suiteFactory_(description);
+      if (definitionFn.length > 0) {
+        throw new Error('describe does not expect any arguments');
+      }
+      if (this.currentDeclarationSuite_.markedExcluding) {
+        suite.exclude();
+      }
+      this.addSpecsToSuite_(suite, definitionFn);
+      if (suite.parentSuite && !suite.children.length) {
+        throw new Error(
+          `describe with no children (describe() or it()): ${suite.getFullName()}`
+        );
+      }
+      return suite;
+    }
+
+    fdescribe(description, definitionFn) {
+      ensureIsFunction(definitionFn, 'fdescribe');
+      const suite = this.suiteFactory_(description);
+      suite.isFocused = true;
+
+      this.focusedRunables.push(suite.id);
+      this.unfocusAncestor_();
+      this.addSpecsToSuite_(suite, definitionFn);
+
+      return suite;
+    }
+
+    xdescribe(description, definitionFn) {
+      ensureIsFunction(definitionFn, 'xdescribe');
+      const suite = this.suiteFactory_(description);
+      suite.exclude();
+      this.addSpecsToSuite_(suite, definitionFn);
+
+      return suite;
+    }
+
+    it(description, fn, timeout) {
+      // it() sometimes doesn't have a fn argument, so only check the type if
+      // it's given.
+      if (arguments.length > 1 && typeof fn !== 'undefined') {
+        ensureIsFunctionOrAsync(fn, 'it');
+      }
+
+      return this.it_(description, fn, timeout);
+    }
+
+    xit(description, fn, timeout) {
+      // xit(), like it(), doesn't always have a fn argument, so only check the
+      // type when needed.
+      if (arguments.length > 1 && typeof fn !== 'undefined') {
+        ensureIsFunctionOrAsync(fn, 'xit');
+      }
+      const spec = this.it_(description, fn, timeout);
+      spec.exclude('Temporarily disabled with xit');
+      return spec;
+    }
+
+    fit(description, fn, timeout) {
+      // Unlike it and xit, the function is required because it doesn't make
+      // sense to focus on nothing.
+      ensureIsFunctionOrAsync(fn, 'fit');
+
+      if (timeout) {
+        j$.util.validateTimeout(timeout);
+      }
+      const spec = this.specFactory_(description, fn, timeout);
+      this.currentDeclarationSuite_.addChild(spec);
+      this.focusedRunables.push(spec.id);
+      this.unfocusAncestor_();
+      return spec;
+    }
+
+    beforeEach(beforeEachFunction, timeout) {
+      ensureIsFunctionOrAsync(beforeEachFunction, 'beforeEach');
+
+      if (timeout) {
+        j$.util.validateTimeout(timeout);
+      }
+
+      this.currentDeclarationSuite_.beforeEach({
+        fn: beforeEachFunction,
+        timeout: timeout || 0
+      });
+    }
+
+    beforeAll(beforeAllFunction, timeout) {
+      ensureIsFunctionOrAsync(beforeAllFunction, 'beforeAll');
+
+      if (timeout) {
+        j$.util.validateTimeout(timeout);
+      }
+
+      this.currentDeclarationSuite_.beforeAll({
+        fn: beforeAllFunction,
+        timeout: timeout || 0
+      });
+    }
+
+    afterEach(afterEachFunction, timeout) {
+      ensureIsFunctionOrAsync(afterEachFunction, 'afterEach');
+
+      if (timeout) {
+        j$.util.validateTimeout(timeout);
+      }
+
+      afterEachFunction.isCleanup = true;
+      this.currentDeclarationSuite_.afterEach({
+        fn: afterEachFunction,
+        timeout: timeout || 0
+      });
+    }
+
+    afterAll(afterAllFunction, timeout) {
+      ensureIsFunctionOrAsync(afterAllFunction, 'afterAll');
+
+      if (timeout) {
+        j$.util.validateTimeout(timeout);
+      }
+
+      this.currentDeclarationSuite_.afterAll({
+        fn: afterAllFunction,
+        timeout: timeout || 0
+      });
+    }
+
+    it_(description, fn, timeout) {
+      if (timeout) {
+        j$.util.validateTimeout(timeout);
+      }
+
+      const spec = this.specFactory_(description, fn, timeout);
+      if (this.currentDeclarationSuite_.markedExcluding) {
+        spec.exclude();
+      }
+      this.currentDeclarationSuite_.addChild(spec);
+
+      return spec;
+    }
+
+    suiteFactory_(description) {
+      const config = this.env_.configuration();
+      return new j$.Suite({
+        id: 'suite' + this.nextSuiteId_++,
+        description,
+        parentSuite: this.currentDeclarationSuite_,
+        timer: new j$.Timer(),
+        expectationFactory: this.expectationFactory_,
+        asyncExpectationFactory: this.suiteAsyncExpectationFactory_,
+        throwOnExpectationFailure: config.stopSpecOnExpectationFailure,
+        autoCleanClosures: config.autoCleanClosures,
+        onLateError: this.onLateError_
+      });
+    }
+
+    addSpecsToSuite_(suite, definitionFn) {
+      const parentSuite = this.currentDeclarationSuite_;
+      parentSuite.addChild(suite);
+      this.currentDeclarationSuite_ = suite;
+
+      try {
+        definitionFn();
+      } catch (e) {
+        suite.handleException(e);
+      }
+
+      this.currentDeclarationSuite_ = parentSuite;
+    }
+
+    specFactory_(description, fn, timeout) {
+      this.totalSpecsDefined++;
+      const config = this.env_.configuration();
+      const suite = this.currentDeclarationSuite_;
+      const spec = new j$.Spec({
+        id: 'spec' + this.nextSpecId_++,
+        beforeAndAfterFns: beforeAndAfterFns(suite),
+        expectationFactory: this.expectationFactory_,
+        asyncExpectationFactory: this.specAsyncExpectationFactory_,
+        onLateError: this.onLateError_,
+        resultCallback: (result, next) => {
+          this.specResultCallback_(spec, result, next);
+        },
+        getSpecName: function(spec) {
+          return getSpecName(spec, suite);
+        },
+        onStart: (spec, next) => this.specStarted_(spec, suite, next),
+        description: description,
+        queueRunnerFactory: this.queueRunnerFactory_,
+        userContext: function() {
+          return suite.clonedSharedUserContext();
+        },
+        queueableFn: {
+          fn: fn,
+          timeout: timeout || 0
+        },
+        throwOnExpectationFailure: config.stopSpecOnExpectationFailure,
+        autoCleanClosures: config.autoCleanClosures,
+        timer: new j$.Timer()
+      });
+      return spec;
+    }
+
+    unfocusAncestor_() {
+      const focusedAncestor = findFocusedAncestor(
+        this.currentDeclarationSuite_
+      );
+
+      if (focusedAncestor) {
+        for (let i = 0; i < this.focusedRunables.length; i++) {
+          if (this.focusedRunables[i] === focusedAncestor) {
+            this.focusedRunables.splice(i, 1);
+            break;
+          }
+        }
+      }
+    }
+  }
+
+  function findFocusedAncestor(suite) {
+    while (suite) {
+      if (suite.isFocused) {
+        return suite.id;
+      }
+      suite = suite.parentSuite;
+    }
+
+    return null;
+  }
+
+  function ensureIsFunction(fn, caller) {
+    if (!j$.isFunction_(fn)) {
+      throw new Error(
+        caller + ' expects a function argument; received ' + j$.getType_(fn)
+      );
+    }
+  }
+
+  function ensureIsFunctionOrAsync(fn, caller) {
+    if (!j$.isFunction_(fn) && !j$.isAsyncFunction_(fn)) {
+      throw new Error(
+        caller + ' expects a function argument; received ' + j$.getType_(fn)
+      );
+    }
+  }
+
+  function beforeAndAfterFns(targetSuite) {
+    return function() {
+      let befores = [],
+        afters = [],
+        suite = targetSuite;
+
+      while (suite) {
+        befores = befores.concat(suite.beforeFns);
+        afters = afters.concat(suite.afterFns);
+
+        suite = suite.parentSuite;
+      }
+
+      return {
+        befores: befores.reverse(),
+        afters: afters
+      };
+    };
+  }
+
+  function getSpecName(spec, suite) {
+    const fullName = [spec.description],
+      suiteFullName = suite.getFullName();
+
+    if (suiteFullName !== '') {
+      fullName.unshift(suiteFullName);
+    }
+    return fullName.join(' ');
+  }
+
+  return SuiteBuilder;
+};
+
 getJasmineRequireObj().Timer = function() {
   const defaultNow = (function(Date) {
     return function() {
diff --git a/spec/core/EnvSpec.js b/spec/core/EnvSpec.js
index 679bd0d0..3d68f24c 100644
--- a/spec/core/EnvSpec.js
+++ b/spec/core/EnvSpec.js
@@ -316,7 +316,7 @@ describe('Env', function() {
 
     it('calls spec.exclude with "Temporarily disabled with xit"', function() {
       const excludeSpy = jasmine.createSpy();
-      spyOn(env, 'it_').and.returnValue({
+      spyOn(jasmineUnderTest.SuiteBuilder.prototype, 'it_').and.returnValue({
         exclude: excludeSpy
       });
       env.xit('foo', function() {});
@@ -327,7 +327,7 @@ describe('Env', function() {
       const pendSpy = jasmine.createSpy();
       const realExclude = jasmineUnderTest.Spec.prototype.exclude;
 
-      spyOn(env, 'it_').and.returnValue({
+      spyOn(jasmineUnderTest.SuiteBuilder.prototype, 'it_').and.returnValue({
         exclude: realExclude,
         pend: pendSpy
       });
diff --git a/spec/core/SuiteBuilderSpec.js b/spec/core/SuiteBuilderSpec.js
new file mode 100644
index 00000000..a24fca1e
--- /dev/null
+++ b/spec/core/SuiteBuilderSpec.js
@@ -0,0 +1,178 @@
+describe('SuiteBuilder', function() {
+  beforeEach(function() {
+    // Rethrow exceptions to ease debugging
+    spyOn(jasmineUnderTest.Suite.prototype, 'handleException').and.callFake(
+      function(e) {
+        throw e;
+      }
+    );
+    spyOn(jasmineUnderTest.Spec.prototype, 'handleException').and.callFake(
+      function(e) {
+        throw e;
+      }
+    );
+  });
+
+  it('creates the top suite', function() {
+    const env = { configuration: () => ({}) };
+    const suiteBuilder = new jasmineUnderTest.SuiteBuilder({ env });
+
+    expect(suiteBuilder.topSuite).toBeInstanceOf(jasmineUnderTest.Suite);
+    expect(suiteBuilder.topSuite.description).toEqual(
+      'Jasmine__TopLevel__Suite'
+    );
+    expect(suiteBuilder.topSuite.parentSuite).toBeUndefined();
+  });
+
+  describe('#describe', function() {
+    definesSuites('describe');
+  });
+
+  describe('#fdescribe', function() {
+    definesSuites('fdescribe');
+
+    it('focuses the suite', function() {
+      const env = { configuration: () => ({}) };
+      const suiteBuilder = new jasmineUnderTest.SuiteBuilder({ env });
+
+      const suite = suiteBuilder.fdescribe('a suite', function() {
+        suiteBuilder.it('a spec');
+      });
+
+      expect(suite.isFocused).toBeTrue();
+      expect(suiteBuilder.focusedRunables).toEqual([suite.id]);
+    });
+
+    it('unfocuses any focused ancestor suite', function() {
+      const env = { configuration: () => ({}) };
+      const suiteBuilder = new jasmineUnderTest.SuiteBuilder({ env });
+
+      const grandparent = suiteBuilder.fdescribe('a suite', function() {
+        suiteBuilder.describe('another suite', function() {
+          suiteBuilder.fdescribe('the focused suite', function() {
+            suiteBuilder.it('a spec');
+          });
+        });
+      });
+
+      expect(suiteBuilder.focusedRunables).not.toContain(grandparent.id);
+    });
+  });
+
+  describe('#xdescribe', function() {
+    definesSuites('xdescribe');
+
+    it('excludes the suite', function() {
+      const env = { configuration: () => ({}) };
+      const suiteBuilder = new jasmineUnderTest.SuiteBuilder({ env });
+
+      const suite = suiteBuilder.xdescribe('a suite', function() {
+        suiteBuilder.it('a spec');
+      });
+
+      expect(suite.markedExcluding).toBeTrue();
+    });
+
+    it('causes child suites to be marked excluded', function() {
+      const env = { configuration: () => ({}) };
+      const suiteBuilder = new jasmineUnderTest.SuiteBuilder({ env });
+
+      let suite;
+      suiteBuilder.xdescribe('a suite', function() {
+        suite = suiteBuilder.describe('another suite', function() {
+          suiteBuilder.it('a spec');
+        });
+      });
+
+      expect(suite.markedExcluding).toBeTrue();
+    });
+  });
+
+  describe('#it', function() {
+    definesSpecs('it');
+  });
+
+  describe('#fit', function() {
+    definesSpecs('fit');
+  });
+
+  describe('#xit', function() {
+    definesSpecs('xit');
+  });
+
+  function definesSuites(fnName) {
+    it('links suites to their parents and children', function() {
+      const env = { configuration: () => ({}) };
+      const suiteBuilder = new jasmineUnderTest.SuiteBuilder({ env });
+
+      let child;
+      const parent = suiteBuilder[fnName]('parent', function() {
+        child = suiteBuilder[fnName]('child', function() {
+          suiteBuilder.it('a spec');
+        });
+      });
+
+      expect(suiteBuilder.topSuite.children).toEqual([sameInstanceAs(parent)]);
+      expect(parent.children).toEqual([sameInstanceAs(child)]);
+      expect(child.parentSuite).toBe(parent);
+      expect(parent.parentSuite).toBe(suiteBuilder.topSuite);
+    });
+
+    it('gives each suite a unique ID', function() {
+      const env = { configuration: () => ({}) };
+      const suiteBuilder = new jasmineUnderTest.SuiteBuilder({ env });
+
+      let child;
+      const parent = suiteBuilder[fnName]('parent', function() {
+        child = suiteBuilder[fnName]('child', function() {
+          suiteBuilder.it('a spec');
+        });
+      });
+
+      const ids = [suiteBuilder.topSuite.id, parent.id, child.id];
+
+      for (const id of ids) {
+        expect(id).toMatch(/^suite[0-9]$/);
+      }
+
+      expect(new Set(ids).size).toEqual(3);
+    });
+  }
+
+  function definesSpecs(fnName) {
+    it('adds the spec to its suite', function() {
+      const env = { configuration: () => ({}) };
+      const suiteBuilder = new jasmineUnderTest.SuiteBuilder({ env });
+
+      let spec;
+      const suite = suiteBuilder.describe('a suite', function() {
+        spec = suiteBuilder[fnName]('a spec', function() {});
+      });
+
+      expect(suite.children).toEqual([sameInstanceAs(spec)]);
+    });
+
+    it('gives each spec a unique ID', function() {
+      const env = { configuration: () => ({}) };
+      const suiteBuilder = new jasmineUnderTest.SuiteBuilder({ env });
+
+      const spec1 = suiteBuilder[fnName]('a spec', function() {});
+      const spec2 = suiteBuilder[fnName]('another spec', function() {});
+
+      expect(spec1.id).toMatch(/^spec[0-9]+$/);
+      expect(spec2.id).toMatch(/^spec[0-9]+$/);
+      expect(spec1.id).not.toEqual(spec2.id);
+    });
+  }
+
+  function sameInstanceAs(expected) {
+    return {
+      asymmetricMatch: function(actual) {
+        return actual === expected;
+      },
+      jasmineToString: function(pp) {
+        return '<same instance as ' + pp(expected) + '>';
+      }
+    };
+  }
+});
diff --git a/src/core/Env.js b/src/core/Env.js
index fc8ccf0c..852e0a8f 100644
--- a/src/core/Env.js
+++ b/src/core/Env.js
@@ -13,8 +13,6 @@ getJasmineRequireObj().Env = function(j$) {
     const self = this;
     const global = options.global || j$.getGlobal();
 
-    let totalSpecsDefined = 0;
-
     const realSetTimeout = global.setTimeout;
     const realClearTimeout = global.clearTimeout;
     const clearStack = j$.getClearStack(global);
@@ -31,14 +29,11 @@ getJasmineRequireObj().Env = function(j$) {
       return r ? r.id : null;
     });
 
-    let topSuite;
     let currentSpec = null;
     const currentlyExecutingSuites = [];
-    const focusedRunables = [];
-    let currentDeclarationSuite = null;
     let hasFailures = false;
-    let deprecator;
     let reporter;
+    let topSuite;
 
     /**
      * This represents the available options to configure Jasmine.
@@ -258,18 +253,6 @@ getJasmineRequireObj().Env = function(j$) {
     j$.Expectation.addCoreMatchers(j$.matchers);
     j$.Expectation.addAsyncCoreMatchers(j$.asyncMatchers);
 
-    let nextSpecId = 0;
-
-    function getNextSpecId() {
-      return 'spec' + nextSpecId++;
-    }
-
-    let nextSuiteId = 0;
-
-    function getNextSuiteId() {
-      return 'suite' + nextSuiteId++;
-    }
-
     const expectationFactory = function(actual, spec) {
       return j$.Expectation.factory({
         matchersUtil: runableResources.makeMatchersUtil(),
@@ -363,43 +346,6 @@ getJasmineRequireObj().Env = function(j$) {
         return spec.addExpectationResult(passed, result);
       }
     };
-    const suiteAsyncExpectationFactory = function(actual, suite) {
-      return asyncExpectationFactory(actual, suite, 'Suite');
-    };
-
-    const specAsyncExpectationFactory = function(actual, suite) {
-      return asyncExpectationFactory(actual, suite, 'Spec');
-    };
-
-    function beforeAndAfterFns(targetSuite) {
-      return function() {
-        let befores = [],
-          afters = [],
-          suite = targetSuite;
-
-        while (suite) {
-          befores = befores.concat(suite.beforeFns);
-          afters = afters.concat(suite.afterFns);
-
-          suite = suite.parentSuite;
-        }
-
-        return {
-          befores: befores.reverse(),
-          afters: afters
-        };
-      };
-    }
-
-    function getSpecName(spec, suite) {
-      const fullName = [spec.description],
-        suiteFullName = suite.getFullName();
-
-      if (suiteFullName !== '') {
-        fullName.unshift(suiteFullName);
-      }
-      return fullName.join(' ');
-    }
 
     /**
      * Causes a deprecation warning to be logged to the console and reported to
@@ -461,16 +407,17 @@ getJasmineRequireObj().Env = function(j$) {
       new j$.QueueRunner(options).execute(args);
     }
 
-    topSuite = new j$.Suite({
-      id: getNextSuiteId(),
-      description: 'Jasmine__TopLevel__Suite',
-      expectationFactory: expectationFactory,
-      asyncExpectationFactory: suiteAsyncExpectationFactory,
-      autoCleanClosures: config.autoCleanClosures,
-      onLateError: recordLateError
+    const suiteBuilder = new j$.SuiteBuilder({
+      env: this,
+      expectationFactory,
+      asyncExpectationFactory,
+      onLateError: recordLateError,
+      specResultCallback,
+      specStarted,
+      queueRunnerFactory
     });
-    deprecator = new j$.Deprecator(topSuite);
-    currentDeclarationSuite = topSuite;
+    topSuite = suiteBuilder.topSuite;
+    const deprecator = new j$.Deprecator(topSuite);
 
     /**
      * Provides the root suite, through which all suites and specs can be
@@ -600,8 +547,8 @@ getJasmineRequireObj().Env = function(j$) {
       installGlobalErrors();
 
       if (!runablesToRun) {
-        if (focusedRunables.length) {
-          runablesToRun = focusedRunables;
+        if (suiteBuilder.focusedRunables.length) {
+          runablesToRun = suiteBuilder.focusedRunables;
         } else {
           runablesToRun = [topSuite.id];
         }
@@ -681,7 +628,7 @@ getJasmineRequireObj().Env = function(j$) {
          */
         reporter.jasmineStarted(
           {
-            totalSpecsDefined: totalSpecsDefined,
+            totalSpecsDefined: suiteBuilder.totalSpecsDefined,
             order: order
           },
           function() {
@@ -702,10 +649,10 @@ getJasmineRequireObj().Env = function(j$) {
                   topSuite.result.failedExpectations.length > 0
                 ) {
                   overallStatus = 'failed';
-                } else if (focusedRunables.length > 0) {
+                } else if (suiteBuilder.focusedRunables.length > 0) {
                   overallStatus = 'incomplete';
                   incompleteReason = 'fit() or fdescribe() was found';
-                } else if (totalSpecsDefined === 0) {
+                } else if (suiteBuilder.totalSpecsDefined === 0) {
                   overallStatus = 'incomplete';
                   incompleteReason = 'No specs found';
                 } else {
@@ -863,22 +810,6 @@ getJasmineRequireObj().Env = function(j$) {
       );
     };
 
-    function ensureIsFunction(fn, caller) {
-      if (!j$.isFunction_(fn)) {
-        throw new Error(
-          caller + ' expects a function argument; received ' + j$.getType_(fn)
-        );
-      }
-    }
-
-    function ensureIsFunctionOrAsync(fn, caller) {
-      if (!j$.isFunction_(fn) && !j$.isAsyncFunction_(fn)) {
-        throw new Error(
-          caller + ' expects a function argument; received ' + j$.getType_(fn)
-        );
-      }
-    }
-
     function ensureIsNotNested(method) {
       const runable = currentRunable();
       if (runable !== null && runable !== undefined) {
@@ -888,150 +819,38 @@ getJasmineRequireObj().Env = function(j$) {
       }
     }
 
-    function suiteFactory(description) {
-      return new j$.Suite({
-        id: getNextSuiteId(),
-        description: description,
-        parentSuite: currentDeclarationSuite,
-        timer: new j$.Timer(),
-        expectationFactory: expectationFactory,
-        asyncExpectationFactory: suiteAsyncExpectationFactory,
-        throwOnExpectationFailure: config.stopSpecOnExpectationFailure,
-        autoCleanClosures: config.autoCleanClosures,
-        onLateError: recordLateError
-      });
-    }
-
-    this.describe = function(description, specDefinitions) {
+    this.describe = function(description, definitionFn) {
       ensureIsNotNested('describe');
-      ensureIsFunction(specDefinitions, 'describe');
-      const suite = suiteFactory(description);
-      if (specDefinitions.length > 0) {
-        throw new Error('describe does not expect any arguments');
-      }
-      if (currentDeclarationSuite.markedExcluding) {
-        suite.exclude();
-      }
-      addSpecsToSuite(suite, specDefinitions);
-      if (suite.parentSuite && !suite.children.length) {
-        throw new Error(
-          'describe with no children (describe() or it()): ' +
-            suite.getFullName()
-        );
-      }
-      return suite.metadata;
+      return suiteBuilder.describe(description, definitionFn).metadata;
     };
 
-    this.xdescribe = function(description, specDefinitions) {
+    this.xdescribe = function(description, definitionFn) {
       ensureIsNotNested('xdescribe');
-      ensureIsFunction(specDefinitions, 'xdescribe');
-      const suite = suiteFactory(description);
-      suite.exclude();
-      addSpecsToSuite(suite, specDefinitions);
-      return suite.metadata;
+      return suiteBuilder.xdescribe(description, definitionFn).metadata;
     };
 
-    this.fdescribe = function(description, specDefinitions) {
+    this.fdescribe = function(description, definitionFn) {
       ensureIsNotNested('fdescribe');
-      ensureIsFunction(specDefinitions, 'fdescribe');
-      const suite = suiteFactory(description);
-      suite.isFocused = true;
-
-      focusedRunables.push(suite.id);
-      unfocusAncestor();
-      addSpecsToSuite(suite, specDefinitions);
-
-      return suite.metadata;
+      return suiteBuilder.fdescribe(description, definitionFn).metadata;
     };
 
-    function addSpecsToSuite(suite, specDefinitions) {
-      const parentSuite = currentDeclarationSuite;
-      parentSuite.addChild(suite);
-      currentDeclarationSuite = suite;
+    function specResultCallback(spec, result, next) {
+      runableResources.clearForRunable(spec.id);
+      currentSpec = null;
 
-      let declarationError = null;
-      try {
-        specDefinitions();
-      } catch (e) {
-        declarationError = e;
+      if (result.status === 'failed') {
+        hasFailures = true;
       }
 
-      if (declarationError) {
-        suite.handleException(declarationError);
-      }
-
-      currentDeclarationSuite = parentSuite;
+      reportSpecDone(spec, result, next);
     }
 
-    function findFocusedAncestor(suite) {
-      while (suite) {
-        if (suite.isFocused) {
-          return suite.id;
-        }
-        suite = suite.parentSuite;
-      }
-
-      return null;
+    function specStarted(spec, suite, next) {
+      currentSpec = spec;
+      runableResources.initForRunable(spec.id, suite.id);
+      reporter.specStarted(spec.result, next);
     }
 
-    function unfocusAncestor() {
-      const focusedAncestor = findFocusedAncestor(currentDeclarationSuite);
-      if (focusedAncestor) {
-        for (let i = 0; i < focusedRunables.length; i++) {
-          if (focusedRunables[i] === focusedAncestor) {
-            focusedRunables.splice(i, 1);
-            break;
-          }
-        }
-      }
-    }
-
-    const specFactory = function(description, fn, suite, timeout) {
-      totalSpecsDefined++;
-      const spec = new j$.Spec({
-        id: getNextSpecId(),
-        beforeAndAfterFns: beforeAndAfterFns(suite),
-        expectationFactory: expectationFactory,
-        asyncExpectationFactory: specAsyncExpectationFactory,
-        onLateError: recordLateError,
-        resultCallback: specResultCallback,
-        getSpecName: function(spec) {
-          return getSpecName(spec, suite);
-        },
-        onStart: specStarted,
-        description: description,
-        queueRunnerFactory: queueRunnerFactory,
-        userContext: function() {
-          return suite.clonedSharedUserContext();
-        },
-        queueableFn: {
-          fn: fn,
-          timeout: timeout || 0
-        },
-        throwOnExpectationFailure: config.stopSpecOnExpectationFailure,
-        autoCleanClosures: config.autoCleanClosures,
-        timer: new j$.Timer()
-      });
-      return spec;
-
-      function specResultCallback(result, next) {
-        runableResources.clearForRunable(spec.id);
-        currentSpec = null;
-
-        if (result.status === 'failed') {
-          hasFailures = true;
-        }
-
-        reportSpecDone(spec, result, next);
-      }
-
-      function specStarted(spec, next) {
-        currentSpec = spec;
-        runableResources.initForRunable(spec.id, suite.id);
-        reporter.specStarted(spec.result, next);
-      }
-    };
-
     function reportSpecDone(spec, result, next) {
       spec.reportedDone = true;
       reporter.specDone(result, next);
@@ -1042,66 +861,19 @@ getJasmineRequireObj().Env = function(j$) {
       reporter.suiteDone(result, next);
     }
 
-    this.it_ = function(description, fn, timeout) {
-      ensureIsNotNested('it');
-      // it() sometimes doesn't have a fn argument, so only check the type if
-      // it's given.
-      if (arguments.length > 1 && typeof fn !== 'undefined') {
-        ensureIsFunctionOrAsync(fn, 'it');
-      }
-
-      if (timeout) {
-        j$.util.validateTimeout(timeout);
-      }
-
-      const spec = specFactory(
-        description,
-        fn,
-        currentDeclarationSuite,
-        timeout
-      );
-      if (currentDeclarationSuite.markedExcluding) {
-        spec.exclude();
-      }
-      currentDeclarationSuite.addChild(spec);
-
-      return spec;
-    };
-
     this.it = function(description, fn, timeout) {
-      const spec = this.it_(description, fn, timeout);
-      return spec.metadata;
+      ensureIsNotNested('it');
+      return suiteBuilder.it(description, fn, timeout).metadata;
     };
 
     this.xit = function(description, fn, timeout) {
       ensureIsNotNested('xit');
-      // xit(), like it(), doesn't always have a fn argument, so only check the
-      // type when needed.
-      if (arguments.length > 1 && typeof fn !== 'undefined') {
-        ensureIsFunctionOrAsync(fn, 'xit');
-      }
-      const spec = this.it_.apply(this, arguments);
-      spec.exclude('Temporarily disabled with xit');
-      return spec.metadata;
+      return suiteBuilder.xit(description, fn, timeout).metadata;
     };
 
     this.fit = function(description, fn, timeout) {
       ensureIsNotNested('fit');
-      ensureIsFunctionOrAsync(fn, 'fit');
-
-      if (timeout) {
-        j$.util.validateTimeout(timeout);
-      }
-      const spec = specFactory(
-        description,
-        fn,
-        currentDeclarationSuite,
-        timeout
-      );
-      currentDeclarationSuite.addChild(spec);
-      focusedRunables.push(spec.id);
-      unfocusAncestor();
-      return spec.metadata;
+      return suiteBuilder.fit(description, fn, timeout).metadata;
     };
 
     /**
@@ -1170,59 +942,22 @@ getJasmineRequireObj().Env = function(j$) {
 
     this.beforeEach = function(beforeEachFunction, timeout) {
       ensureIsNotNested('beforeEach');
-      ensureIsFunctionOrAsync(beforeEachFunction, 'beforeEach');
-
-      if (timeout) {
-        j$.util.validateTimeout(timeout);
-      }
-
-      currentDeclarationSuite.beforeEach({
-        fn: beforeEachFunction,
-        timeout: timeout || 0
-      });
+      suiteBuilder.beforeEach(beforeEachFunction, timeout);
     };
 
     this.beforeAll = function(beforeAllFunction, timeout) {
       ensureIsNotNested('beforeAll');
-      ensureIsFunctionOrAsync(beforeAllFunction, 'beforeAll');
-
-      if (timeout) {
-        j$.util.validateTimeout(timeout);
-      }
-
-      currentDeclarationSuite.beforeAll({
-        fn: beforeAllFunction,
-        timeout: timeout || 0
-      });
+      suiteBuilder.beforeAll(beforeAllFunction, timeout);
     };
 
     this.afterEach = function(afterEachFunction, timeout) {
       ensureIsNotNested('afterEach');
-      ensureIsFunctionOrAsync(afterEachFunction, 'afterEach');
-
-      if (timeout) {
-        j$.util.validateTimeout(timeout);
-      }
-
-      afterEachFunction.isCleanup = true;
-      currentDeclarationSuite.afterEach({
-        fn: afterEachFunction,
-        timeout: timeout || 0
-      });
+      suiteBuilder.afterEach(afterEachFunction, timeout);
     };
 
     this.afterAll = function(afterAllFunction, timeout) {
       ensureIsNotNested('afterAll');
-      ensureIsFunctionOrAsync(afterAllFunction, 'afterAll');
-
-      if (timeout) {
-        j$.util.validateTimeout(timeout);
-      }
-
-      currentDeclarationSuite.afterAll({
-        fn: afterAllFunction,
-        timeout: timeout || 0
-      });
+      suiteBuilder.afterAll(afterAllFunction, timeout);
     };
 
     this.pending = function(message) {
diff --git a/src/core/SuiteBuilder.js b/src/core/SuiteBuilder.js
new file mode 100644
index 00000000..f5017529
--- /dev/null
+++ b/src/core/SuiteBuilder.js
@@ -0,0 +1,304 @@
+getJasmineRequireObj().SuiteBuilder = function(j$) {
+  class SuiteBuilder {
+    constructor(options) {
+      this.env_ = options.env;
+      this.expectationFactory_ = options.expectationFactory;
+      this.suiteAsyncExpectationFactory_ = function(actual, suite) {
+        return options.asyncExpectationFactory(actual, suite, 'Suite');
+      };
+      this.specAsyncExpectationFactory_ = function(actual, suite) {
+        return options.asyncExpectationFactory(actual, suite, 'Spec');
+      };
+      this.onLateError_ = options.onLateError;
+      this.specResultCallback_ = options.specResultCallback;
+      this.specStarted_ = options.specStarted;
+      this.queueRunnerFactory_ = options.queueRunnerFactory;
+
+      this.nextSuiteId_ = 0;
+      this.nextSpecId_ = 0;
+
+      this.topSuite = this.suiteFactory_('Jasmine__TopLevel__Suite');
+      this.currentDeclarationSuite_ = this.topSuite;
+      this.totalSpecsDefined = 0;
+      this.focusedRunables = [];
+    }
+
+    describe(description, definitionFn) {
+      ensureIsFunction(definitionFn, 'describe');
+      const suite = this.suiteFactory_(description);
+      if (definitionFn.length > 0) {
+        throw new Error('describe does not expect any arguments');
+      }
+      if (this.currentDeclarationSuite_.markedExcluding) {
+        suite.exclude();
+      }
+      this.addSpecsToSuite_(suite, definitionFn);
+      if (suite.parentSuite && !suite.children.length) {
+        throw new Error(
+          `describe with no children (describe() or it()): ${suite.getFullName()}`
+        );
+      }
+      return suite;
+    }
+
+    fdescribe(description, definitionFn) {
+      ensureIsFunction(definitionFn, 'fdescribe');
+      const suite = this.suiteFactory_(description);
+      suite.isFocused = true;
+
+      this.focusedRunables.push(suite.id);
+      this.unfocusAncestor_();
+      this.addSpecsToSuite_(suite, definitionFn);
+
+      return suite;
+    }
+
+    xdescribe(description, definitionFn) {
+      ensureIsFunction(definitionFn, 'xdescribe');
+      const suite = this.suiteFactory_(description);
+      suite.exclude();
+      this.addSpecsToSuite_(suite, definitionFn);
+
+      return suite;
+    }
+
+    it(description, fn, timeout) {
+      // it() sometimes doesn't have a fn argument, so only check the type if
+      // it's given.
+      if (arguments.length > 1 && typeof fn !== 'undefined') {
+        ensureIsFunctionOrAsync(fn, 'it');
+      }
+
+      return this.it_(description, fn, timeout);
+    }
+
+    xit(description, fn, timeout) {
+      // xit(), like it(), doesn't always have a fn argument, so only check the
+      // type when needed.
+      if (arguments.length > 1 && typeof fn !== 'undefined') {
+        ensureIsFunctionOrAsync(fn, 'xit');
+      }
+      const spec = this.it_(description, fn, timeout);
+      spec.exclude('Temporarily disabled with xit');
+      return spec;
+    }
+
+    fit(description, fn, timeout) {
+      // Unlike it and xit, the function is required because it doesn't make
+      // sense to focus on nothing.
+      ensureIsFunctionOrAsync(fn, 'fit');
+
+      if (timeout) {
+        j$.util.validateTimeout(timeout);
+      }
+      const spec = this.specFactory_(description, fn, timeout);
+      this.currentDeclarationSuite_.addChild(spec);
+      this.focusedRunables.push(spec.id);
+      this.unfocusAncestor_();
+      return spec;
+    }
+
+    beforeEach(beforeEachFunction, timeout) {
+      ensureIsFunctionOrAsync(beforeEachFunction, 'beforeEach');
+
+      if (timeout) {
+        j$.util.validateTimeout(timeout);
+      }
+
+      this.currentDeclarationSuite_.beforeEach({
+        fn: beforeEachFunction,
+        timeout: timeout || 0
+      });
+    }
+
+    beforeAll(beforeAllFunction, timeout) {
+      ensureIsFunctionOrAsync(beforeAllFunction, 'beforeAll');
+
+      if (timeout) {
+        j$.util.validateTimeout(timeout);
+      }
+
+      this.currentDeclarationSuite_.beforeAll({
+        fn: beforeAllFunction,
+        timeout: timeout || 0
+      });
+    }
+
+    afterEach(afterEachFunction, timeout) {
+      ensureIsFunctionOrAsync(afterEachFunction, 'afterEach');
+
+      if (timeout) {
+        j$.util.validateTimeout(timeout);
+      }
+
+      afterEachFunction.isCleanup = true;
+      this.currentDeclarationSuite_.afterEach({
+        fn: afterEachFunction,
+        timeout: timeout || 0
+      });
+    }
+
+    afterAll(afterAllFunction, timeout) {
+      ensureIsFunctionOrAsync(afterAllFunction, 'afterAll');
+
+      if (timeout) {
+        j$.util.validateTimeout(timeout);
+      }
+
+      this.currentDeclarationSuite_.afterAll({
+        fn: afterAllFunction,
+        timeout: timeout || 0
+      });
+    }
+
+    it_(description, fn, timeout) {
+      if (timeout) {
+        j$.util.validateTimeout(timeout);
+      }
+
+      const spec = this.specFactory_(description, fn, timeout);
+      if (this.currentDeclarationSuite_.markedExcluding) {
+        spec.exclude();
+      }
+      this.currentDeclarationSuite_.addChild(spec);
+
+      return spec;
+    }
+
+    suiteFactory_(description) {
+      const config = this.env_.configuration();
+      return new j$.Suite({
+        id: 'suite' + this.nextSuiteId_++,
+        description,
+        parentSuite: this.currentDeclarationSuite_,
+        timer: new j$.Timer(),
+        expectationFactory: this.expectationFactory_,
+        asyncExpectationFactory: this.suiteAsyncExpectationFactory_,
+        throwOnExpectationFailure: config.stopSpecOnExpectationFailure,
+        autoCleanClosures: config.autoCleanClosures,
+        onLateError: this.onLateError_
+      });
+    }
+
+    addSpecsToSuite_(suite, definitionFn) {
+      const parentSuite = this.currentDeclarationSuite_;
+      parentSuite.addChild(suite);
+      this.currentDeclarationSuite_ = suite;
+
+      try {
+        definitionFn();
+      } catch (e) {
+        suite.handleException(e);
+      }
+
+      this.currentDeclarationSuite_ = parentSuite;
+    }
+
+    specFactory_(description, fn, timeout) {
+      this.totalSpecsDefined++;
+      const config = this.env_.configuration();
+      const suite = this.currentDeclarationSuite_;
+      const spec = new j$.Spec({
+        id: 'spec' + this.nextSpecId_++,
+        beforeAndAfterFns: beforeAndAfterFns(suite),
+        expectationFactory: this.expectationFactory_,
+        asyncExpectationFactory: this.specAsyncExpectationFactory_,
+        onLateError: this.onLateError_,
+        resultCallback: (result, next) => {
+          this.specResultCallback_(spec, result, next);
+        },
+        getSpecName: function(spec) {
+          return getSpecName(spec, suite);
+        },
+        onStart: (spec, next) => this.specStarted_(spec, suite, next),
+        description: description,
+        queueRunnerFactory: this.queueRunnerFactory_,
+        userContext: function() {
+          return suite.clonedSharedUserContext();
+        },
+        queueableFn: {
+          fn: fn,
+          timeout: timeout || 0
+        },
+        throwOnExpectationFailure: config.stopSpecOnExpectationFailure,
+        autoCleanClosures: config.autoCleanClosures,
+        timer: new j$.Timer()
+      });
+      return spec;
+    }
+
+    unfocusAncestor_() {
+      const focusedAncestor = findFocusedAncestor(
+        this.currentDeclarationSuite_
+      );
+
+      if (focusedAncestor) {
+        for (let i = 0; i < this.focusedRunables.length; i++) {
+          if (this.focusedRunables[i] === focusedAncestor) {
+            this.focusedRunables.splice(i, 1);
+            break;
+          }
+        }
+      }
+    }
+  }
+
+  function findFocusedAncestor(suite) {
+    while (suite) {
+      if (suite.isFocused) {
+        return suite.id;
+      }
+      suite = suite.parentSuite;
+    }
+
+    return null;
+  }
+
+  function ensureIsFunction(fn, caller) {
+    if (!j$.isFunction_(fn)) {
+      throw new Error(
+        caller + ' expects a function argument; received ' + j$.getType_(fn)
+      );
+    }
+  }
+
+  function ensureIsFunctionOrAsync(fn, caller) {
+    if (!j$.isFunction_(fn) && !j$.isAsyncFunction_(fn)) {
+      throw new Error(
+        caller + ' expects a function argument; received ' + j$.getType_(fn)
+      );
+    }
+  }
+
+  function beforeAndAfterFns(targetSuite) {
+    return function() {
+      let befores = [],
+        afters = [],
+        suite = targetSuite;
+
+      while (suite) {
+        befores = befores.concat(suite.beforeFns);
+        afters = afters.concat(suite.afterFns);
+
+        suite = suite.parentSuite;
+      }
+
+      return {
+        befores: befores.reverse(),
+        afters: afters
+      };
+    };
+  }
+
+  function getSpecName(spec, suite) {
+    const fullName = [spec.description],
+      suiteFullName = suite.getFullName();
+
+    if (suiteFullName !== '') {
+      fullName.unshift(suiteFullName);
+    }
+    return fullName.join(' ');
+  }
+
+  return SuiteBuilder;
+};
diff --git a/src/core/requireCore.js b/src/core/requireCore.js
index faa6b86e..a628e6ea 100644
--- a/src/core/requireCore.js
+++ b/src/core/requireCore.js
@@ -78,6 +78,7 @@ var getJasmineRequireObj = (function(jasmineGlobal) {
     j$.StringContaining = jRequire.StringContaining(j$);
     j$.UserContext = jRequire.UserContext(j$);
     j$.Suite = jRequire.Suite(j$);
+    j$.SuiteBuilder = jRequire.SuiteBuilder(j$);
     j$.Timer = jRequire.Timer();
     j$.TreeProcessor = jRequire.TreeProcessor();
     j$.version = jRequire.version();