robber 1.0.1

BDD / TDD assertion library for Python

robber.py - BDD / TDD assertion library for Python.

Synopsis

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.

Assertions

eq/==

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

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

Also:

expect(1) == 1

ne/not_eq/!=

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

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

equal

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

expect(1).to.equal(1)

not_equal

Asserts that the target is not identical (is) to the expected:

expect({ 'test': 'robber' }).to.not_equal({ 'test': 'robber' })

true

Asserts that the target is True:

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

false

Asserts that the target is False:

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

instanceof

Asserts that the target is an instance of expected:

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

match

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

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

not_match

Asserts that the target can not be matched by a regular expression:

expect('bar').to.not_match(r'foo')

respond_to

Asserts that the target responds to a method:

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

truthy

Asserts that the target is truthy:

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

falsy

Asserts that the target is falsy:

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

length

Asserts that the target has a length of expected:

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

empty

Asserts that the target is empty:

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

not_empty

Asserts that the target is nonempty:

expect([1, 2, 3]).to.be.not_empty()
expect('foo').to.be.not_empty()

string

Asserts that the target is a string:

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

integer

Asserts that the target is an integer:

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

float

Asserts that the target is floating point number:

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

list

Asserts that the target is a list:

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

dict

Asserts that the target is a dictionary:

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

tuple

Asserts that the target is a tuple:

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

none

Asserts that the target is None:

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

above

Asserts that the target is above expected:

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

below

Asserts that the target is below expected:

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

within

Asserts that the target is within expected:

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

contain

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

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

not_contain/exclude

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

expect([1,2,3]).to.not_contain(4)
expect({'foo': 'bar'}).to.exclude('baz')

Language chains

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

• to

• be

• a

• an

• have

For example, the following two lines are functionally equivalent:

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

expect(1.0).float()

Expectation chaining

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)

Custom assertions

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')

Custom error messages

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)

Installation

$ pip install robber

Requirements

• Python 2.6, 2.7 or 3.5

• pip

• nose (for testing)

Tests

$ nosetests tests/

License

MIT License