25816a6e77
Custom object formatters allow users to customize how an object is
stringified in matcher failure messages. This can already be done by
adding a `jasmineToString` method to the objects in question. But
it's not always desirable or possible to do that, particularly when
objects of a given "type" do not inherit from a specific prototype.
For instance, suppose a web service returns a list of foos that are
deserialized from JSON, e.g.:
{ fooId: 42, /* more properties */ }
The only way to define `jasmineToString` on those is by writing code to
add it to each instance at runtime. But a custom object formatter can
recognize that the object it's looking at is a foo and format it
accordingly:
jasmine.addCustomObjectFormatter(function(obj) {
if (typeof obj.fooId !== 'number') {
return undefined;
}
return '[Foo with ID ' + obj.fooId + ']';
});
Unlike `jasmineToString`, custom object formatters are scoped to a
particular spec or suite and don't require any changes to the code
under test.
68 lines
2.2 KiB
JavaScript
68 lines
2.2 KiB
JavaScript
describe("Custom object formatters", function() {
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var env;
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beforeEach(function() {
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env = new jasmineUnderTest.Env();
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env.configure({random: false});
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});
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it("scopes custom object formatters to a spec", function(done) {
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env.it('a spec with custom pretty-printer', function() {
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env.addCustomObjectFormatter(function(obj) { return 'custom(' + obj + ')'; });
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env.expect(42).toBeUndefined();
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});
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env.it('a spec without custom pretty-printer', function() {
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env.expect(42).toBeUndefined();
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});
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var specResults = [];
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var specDone = function(result) {
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specResults.push(result);
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};
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var expectations = function() {
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expect(specResults[0].failedExpectations[0].message).toEqual("Expected custom(42) to be undefined.");
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expect(specResults[1].failedExpectations[0].message).toEqual("Expected 42 to be undefined.");
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done();
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};
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env.addReporter({ specDone:specDone, jasmineDone: expectations});
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env.execute();
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});
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it("scopes custom object formatters to a suite", function(done) {
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env.it('a spec without custom pretty-printer', function() {
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env.expect(42).toBeUndefined();
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});
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env.describe('with custom pretty-printer', function() {
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env.beforeEach(function() {
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env.addCustomObjectFormatter(function(obj) { return 'custom(' + obj + ')'; });
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});
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env.it('a spec', function() {
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env.expect(42).toBeUndefined();
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});
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});
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var specResults = [];
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var specDone = function(result) {
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specResults.push(result);
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};
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var expectations = function() {
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expect(specResults[0].failedExpectations[0].message).toEqual("Expected 42 to be undefined.");
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expect(specResults[1].failedExpectations[0].message).toEqual("Expected custom(42) to be undefined.");
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done();
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};
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env.addReporter({ specDone:specDone, jasmineDone: expectations});
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env.execute();
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});
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it("throws an exception if you try to add a custom object formatter outside a runable", function() {
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expect(function() {
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env.addCustomObjectFormatter(function() {});
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}).toThrowError('Custom object formatters must be added in a before function or a spec')
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});
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});
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