Equality & Comparison Assertions

These assertions test equality, identity, and value comparisons.

to be

Aliases: to be, to equal, equals, is, is equal to, to strictly equal

Success:

expect(42, 'to be', 42);
expect('hello', 'to equal', 'hello');
expect(true, 'is', true);
expect(null, 'is equal to', null);
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Failure:

expect(42, 'to be', '42');
// AssertionError: Expected 42 to be '42'
expect({}, 'to equal', {});
// AssertionError: Expected {} to equal {}
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Negation:

expect(42, 'not to be', '42');
expect({}, 'not to equal', {});
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to deep equal

Aliases: to deep equal, to deeply equal

Success:

expect({ a: 1, b: 2 }, 'to deep equal', { a: 1, b: 2 });
expect([1, 2, 3], 'to deeply equal', [1, 2, 3]);
expect({ nested: { value: 42 } }, 'to deep equal', { nested: { value: 42 } });
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Failure:

expect({ a: 1 }, 'to deep equal', { a: 1, b: 2 });
// AssertionError: Expected { a: 1 } to deep equal { a: 1, b: 2 }
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Negation:

expect({ a: 1 }, 'not to deep equal', { a: 1, b: 2 });
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to be one of <array>

Success:

expect(2, 'to be one of', [1, 2, 3]);
expect('blue', 'to be one of', ['red', 'green', 'blue']);
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Failure:

expect(5, 'to be one of', [1, 2, 3]);
// AssertionError: Expected 5 to be one of [1, 2, 3]
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Negation:

expect(5, 'not to be one of', [1, 2, 3]);
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to be an instance of <constructor>

Aliases: to be an instance of <constructor>, to be a <constructor>

Success:

expect(new Date(), 'to be an instance of', Date);
expect([], 'to be a', Array);
expect('hello', 'to be an instance of', String); // Note: primitive strings work too
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Failure:

expect('hello', 'to be an instance of', Number);
// AssertionError: Expected 'hello' to be an instance of Number
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Negation:

expect('hello', 'not to be an instance of', Number);
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to be a <constructor> / to be an <constructor>

Aliases: to be a <constructor>, to be an <constructor>

Success:

expect(new Date(), 'to be a', Date);
expect(new Error(), 'to be an', Error);
expect([], 'to be an', Array);
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Failure:

expect('hello', 'to be a', Number);
// AssertionError: Expected 'hello' to be a Number
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Negation:

expect('hello', 'not to be a', Number);
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