spyOn explicitly checks to see that a method name to spy on was passed.

[finish #27689237]

lib/jasmine-core/jasmine.js

@@ -1864,6 +1864,10 @@ getJasmineRequireObj().SpyRegistry = function(j$) {
         throw new Error('spyOn could not find an object to spy upon for ' + methodName + '()');
       }
 
+      if (j$.util.isUndefined(methodName)) {
+        throw new Error('No method name supplied');
+      }
+
       if (j$.util.isUndefined(obj[methodName])) {
         throw new Error(methodName + '() method does not exist');
       }

spec/core/SpyRegistrySpec.js

@@ -7,6 +7,15 @@ describe("SpyRegistry", function() {
       }).toThrowError(/could not find an object/);
     });
 
+    it("checks that a method name was passed", function() {
+      var spyRegistry = new j$.SpyRegistry(),
+        subject = {};
+
+        expect(function() {
+          spyRegistry.spyOn(subject);
+        }).toThrowError(/No method name supplied/);
+    });
+
     it("checks for the existence of the method", function() {
       var spyRegistry = new j$.SpyRegistry(),
         subject = {};

src/core/SpyRegistry.js

@@ -9,6 +9,10 @@ getJasmineRequireObj().SpyRegistry = function(j$) {
         throw new Error('spyOn could not find an object to spy upon for ' + methodName + '()');
       }
 
+      if (j$.util.isUndefined(methodName)) {
+        throw new Error('No method name supplied');
+      }
+
       if (j$.util.isUndefined(obj[methodName])) {
         throw new Error(methodName + '() method does not exist');
       }