• robber.py now supports python 2.6, 2.7, 3.4, 3.5 and python 3.6

In order to use robber, you need to import expect from the module:

from robber import expect

That's all. You are good to go.

Asserts that actual is equal (==) to expected:

expect(1).to.eq(1)
expect([1, 2]).to.eq([1, 2])

Also:

expect(1) == 1

Asserts that actual is not equal (!=) to expected:

expect(1).to.ne(2)
expect(1).to != 2
expect(1) != 2

Asserts that the target is identical (is) to the expected:

expect(1).to.equal(1)

Asserts that the target is True:

expect(True).to.be.true()

Asserts that the target is False:

expect(False).to.be.false()

Asserts that the target is an instance of expected:

expect(obj).to.be.instanceof(Klass)

Asserts that the target can be matched by a regular expression:

expect('foo').to.match(r'foo')

Asserts that the target responds to a method:

expect(obj).to.respond_to('method')

Asserts that the target is truthy:

expect(['test']).to.be.truthy()

Asserts that the target is falsy:

expect([]).to.be.falsy()

Asserts that the target has a length of expected:

expect([1, 2]).to.have.length(2)
expect('str').to.have.length(3)

Asserts that the target is empty:

expect([]).to.be.empty()
expect('').to.be.empty()

Asserts that the target is a string:

expect('str').to.be.a.string()

Asserts that the target is an integer:

expect('str').to.be.an.integer()

Asserts that the target is floating point number:

expect(1.0).to.be.a.float()

Asserts that the target is a list:

expect([1, 2]).to.be.a.list()

Asserts that the target is a dictionary:

expect({}).to.be.a.dict()

Asserts that the target is a tuple:

expect((1, 2)).to.be.a.tuple()

Asserts that the target is None:

expect(None).to.be.none()

Asserts that the target is above expected:

expect(2).to.be.above(1)

Asserts that the target is below expected:

expect(1).to.be.below(2)

Asserts that the target is within expected:

expect(2).to.be.within(0, 2)

Asserts that the target contains an element, or a key:

expect([1,2,3]).to.contain(2)
expect({'foo': 'bar'}).to.contain('foo')

Asserts that the target does not contain an element, or a key:

expect({'foo': 'bar'}).to.exclude('baz')

Asserts that the target throws an exception

expect(lambda: raise_exception(...)).to.throw(Exception)
expect(any_callable).to.throw(Exception)

Asserts that a mock has been called

expect(mock).to.be.called()

Asserts that a mock has been called exactly one time

expect(mock).to.be.called_once()

Asserts that a object is callable

expect(object).to.be.callable()

Asserts that a mock has been called with params

expect(mock).to.be.called_with(*args, **kwargs)

Asserts that a mock has been called once with params

expect(mock).to.be.called_once_with(*args, **kwargs)

Asserts that a mock has ever been called with params. The call is not necessary to be to latest one (the same as assert.any_call).

expect(mock).to.have.been.ever_called_with(*args, **kwargs)

In order to write more readable assertions, there are a few built-in language chains that you can use:

• to
• be
• been
• a
• an
• have

• not_to

For example, the following two lines are functionally equivalent:

expect(1.0).to.be.a.float()
expect(1.0).float()

In the spirit of more readable assertions, and to eliminate redundant evaluations of the same expression, you can chain multiple expectations.

For example, the following two lines are functionally equivalent. The first example evaluates the expression '1 + 1' only once:

expect(1 + 1).to.be.an.integer().to.be.within(1, 3)

expect(1 + 1).to.be.an.integer()
expect(1 + 1).to.be within(1, 3)

Writing custom assertion is as easy as extending a base matcher class and adding two methods - matches for matching and failure_message for the error notice:

class Chain(Base):
    def matches(self):
        expectation = self.actual(None)
        chain = getattr(expectation, self.expected)
        return expectation is chain

    def failure_message(self):
        return 'Expected "%s" to have chain "%s"' % (self.actual, self.expected)

expect.register('chain', Chain)

After you register the new matcher, you can use it as expected:

expect(obj).to.have.chain('be')

If you want to have custom failure messages, for assertion or group of assertions, you can simply do:

from robber import failure_message

with failure_message('Something went wrong'):
    expect(1).to.eq(2)

$ pip install robber

• Python 2.6, 2.7 or 3.5
• pip
• nose (for testing)

$ nosetests tests/

MIT License