This module exports the expect function, that is the kickoff to
create "expectations" over a specific element as shown in the following
example:
Example
expect(x+y).toBeGreaterThan(z) .orThrow(newError('x and y need to add up to more than z'));
The expect function expects to receive a single argument of any type.
Given that element a new "expectation" is returned, whose specific type depends
of the type of the element given to expect as an argument. So expect(x)
returns an expectation. An expectation is an object that accepts any number of
matchers to be called upon it, such as toBe, toBeGreaterThan, toHaveLength
and so on. The specific set of matchers available depends on the type of the
expectation, which, as said, depends on the type of the argument given to
expect.
When a matcher is called, the element given to expect is passed to the
Expectations/Matchers as the actual value, where the additional arguments over the
matcher are the arguments given to the matcher method called, so for example,
expect(x).toBe(y) calls the Expectations/Matchers.toBe with x as actual argument
and y as expected argument.
Once the first matcher is called over an expectation, a Expectations/Interfaces.FinishedExpectation
is obtained. A finished matcher has a result, that may be one of true
(if the matcher was satisfied) or false if not. A finished matcher may be
queried for the result, by calling getResult,
but additional helper methods are provided by the interface in order to fulfill
different needs, such as throwing an error if the expectation was not satisfied,
or calling a function if it was.
New matchers may be called over a finished expectation, and the result of the
matcher would be calculated as an "and" over all the results. e.g.
expect(x).toBeGreaterThan(y).toBeLowerThan(z). This creates a new expectations
that is satisfied only when both parts (x being greater than y, and x being
lower than z) are true. This itself returns a new Expectations/Interfaces.FinishedExpectation,
that can be extended with new matchers, or queried about the results as
previously mentioned.
This module exports the expect function, that is the kickoff to create "expectations" over a specific element as shown in the following example:
Example
The expect function expects to receive a single argument of any type. Given that element a new "expectation" is returned, whose specific type depends of the type of the element given to expect as an argument. So
expect(x)returns an expectation. An expectation is an object that accepts any number of matchers to be called upon it, such astoBe,toBeGreaterThan,toHaveLengthand so on. The specific set of matchers available depends on the type of the expectation, which, as said, depends on the type of the argument given to expect.When a matcher is called, the element given to expect is passed to the Expectations/Matchers as the actual value, where the additional arguments over the matcher are the arguments given to the matcher method called, so for example,
expect(x).toBe(y)calls the Expectations/Matchers.toBe withxasactualargument andyasexpectedargument.Once the first matcher is called over an expectation, a Expectations/Interfaces.FinishedExpectation is obtained. A finished matcher has a result, that may be one of
true(if the matcher was satisfied) orfalseif not. A finished matcher may be queried for the result, by calling getResult, but additional helper methods are provided by the interface in order to fulfill different needs, such as throwing an error if the expectation was not satisfied, or calling a function if it was.New matchers may be called over a finished expectation, and the result of the matcher would be calculated as an "and" over all the results. e.g.
expect(x).toBeGreaterThan(y).toBeLowerThan(z). This creates a new expectations that is satisfied only when both parts (x being greater than y, and x being lower than z) are true. This itself returns a new Expectations/Interfaces.FinishedExpectation, that can be extended with new matchers, or queried about the results as previously mentioned.To see a list of all matchers, read the expect documentation, and the Expectations/Matchers documentation.
Author
Alan Rodas Bonjour alanrodas@gmail.com