doc.go

// Licensed under the MIT license, see LICENCE file for details.

/*
Package quicktest provides a collection of Go helpers for writing tests.

Quicktest helpers can be easily integrated inside regular Go tests, for
instance:

    import qt "github.com/frankban/quicktest"

    func TestFoo(t *testing.T) {
        t.Run("numbers", func(t *testing.T) {
            c := qt.New(t)
            numbers, err := somepackage.Numbers()
            c.Assert(numbers, qt.DeepEquals, []int{42, 47})
            c.Assert(err, qt.ErrorMatches, "bad wolf")
        })
        t.Run("nil", func(t *testing.T) {
            c := qt.New(t)
            got := somepackage.MaybeNil()
            c.Assert(got, qt.IsNil, qt.Commentf("value: %v", somepackage.Value))
        })
    }

Deferred execution

Quicktest provides the ability to defer the execution of functions that will be
run when the test completes. This is often useful for creating OS-level
resources such as temporary directories (see c.Mkdir). The functions will be
run in last-in, first-out order.

    func (c *C) Defer(f func())

To trigger the deferred behavior, call c.Done:

    func (c *C) Done()

If you create a *C instance at the top level, you’ll have to add a defer to
trigger the cleanups at the end of the test:

    defer c.Done()

However, if you use quicktest to create a subtest, Done will be called
automatically at the end of that subtest. For example:

    func TestFoo(t *testing.T) {
        c := qt.New(t)
        c.Run("subtest", func(c *qt.C) {
            c.Setenv("HOME", c.Mkdir())
            // Here $HOME is set the path to a newly created directory.
            // At the end of the test the directory will be removed
            // and HOME set back to its original value.
        })
    }

Assertions

An assertion looks like this, where qt.Equals could be replaced by any
available checker. If the assertion fails, the underlying Fatal method is
called to describe the error and abort the test.

    c.Assert(someValue, qt.Equals, wantValue)

If you don’t want to abort on failure, use Check instead, which calls Error
instead of Fatal:

    c.Check(someValue, qt.Equals, wantValue)

The library provides some base checkers like Equals, DeepEquals, Matches,
ErrorMatches, IsNil and others. More can be added by implementing the Checker
interface. Here is a list of checkers already included in the package.

Equals

Equals checks that two values are equal, as compared with Go's == operator.

For instance:

    c.Assert(answer, qt.Equals, 42)

Note that the following will fail:

    c.Assert((*sometype)(nil), qt.Equals, nil)

Use the IsNil checker below for this kind of nil check.

DeepEquals

DeepEquals checks that two arbitrary values are deeply equal.
The comparison is done using the github.com/google/go-cmp/cmp package.
When comparing structs, by default no exported fields are allowed.
If a more sophisticated comparison is required, use CmpEquals (see below).

Example call:

    c.Assert(got, qt.DeepEquals, []int{42, 47})

CmpEquals

CmpEquals checks equality of two arbitrary values according to the provided
compare options. DeepEquals is more commonly used when no compare options are
required.

Example calls:

    c.Assert(list, qt.CmpEquals(cmpopts.SortSlices), []int{42, 47})
    c.Assert(got, qt.CmpEquals(), []int{42, 47}) // Same as qt.DeepEquals.

Matches

Matches checks that a string or result of calling the String method
(if the value implements fmt.Stringer) matches the provided regular expression.

For instance:

    c.Assert("these are the voyages", qt.Matches, `these are .*`)
    c.Assert(net.ParseIP("1.2.3.4"), qt.Matches, `1.*`)

ErrorMatches

ErrorMatches checks that the provided value is an error whose message matches
the provided regular expression.

For instance:

    c.Assert(err, qt.ErrorMatches, `bad wolf .*`)

PanicMatches

PanicMatches checks that the provided function panics with a message matching
the provided regular expression.

For instance:

    c.Assert(func() {panic("bad wolf ...")}, qt.PanicMatches, `bad wolf .*`)

IsNil

IsNil checks that the provided value is nil.

For instance:

    c.Assert(got, qt.IsNil)

HasLen

HasLen checks that the provided value has the given length.

For instance:

    c.Assert([]int{42, 47}, qt.HasLen, 2)
    c.Assert(myMap, qt.HasLen, 42)

Satisfies

Satisfies checks that the provided value, when used as argument of the provided
predicate function, causes the function to return true. The function must be of
type func(T) bool, having got assignable to T.

For instance:

    // Check that an error from os.Open satisfies os.IsNotExist.
    c.Assert(err, qt.Satisfies, os.IsNotExist)

    // Check that a floating point number is a not-a-number.
    c.Assert(f, qt.Satisfies, math.IsNaN)

Not

Not returns a Checker negating the given Checker.

For instance:

    c.Assert(got, qt.Not(qt.IsNil))
    c.Assert(answer, qt.Not(qt.Equals), 42)

Contains

Contains checks that a map, slice, array or string contains a value. It's the
same as using Any(Equals), except that it has a special case for strings - if
the first argument is a string, the second argument must also be a string and
strings.Contains will be used.

For example:

	c.Assert("hello world", qt.Contains, "world")
	c.Assert([]int{3,5,7,99}, qt.Contains, 7)

Any

Any returns a Checker that uses the given checker to check elements of a slice
or array or the values from a map. It succeeds if any element passes the check.

For example:

	c.Assert([]int{3,5,7,99}, qt.Any(qt.Equals), 7)
	c.Assert([][]string{{"a", "b"}, {"c", "d"}}, qt.Any(qt.DeepEquals), []string{"c", "d"})

See also All and Contains.

All

All returns a Checker that uses the given checker to check elements of slice or
array or the values of a map. It succeeds if all elements pass the check.
On failure it prints the error from the first index that failed.

For example:

	c.Assert([]int{3, 5, 8}, qt.All(qt.Not(qt.Equals)), 0)
	c.Assert([][]string{{"a", "b"}, {"a", "b"}}, qt.All(qt.DeepEquals), []string{"c", "d"})

See also Any and Contains.

JSONEquals

JSONEquals checks whether a byte slice or string is JSON-equivalent to a Go
value. See CodecEquals for more information.

It uses DeepEquals to do the comparison. If a more sophisticated comparison is
required, use CodecEquals directly.

For instance:

    c.Assert(`{"First": 47.11}`, qt.JSONEquals, &MyStruct{First: 47.11})

CodecEquals

CodecEquals returns a checker that checks for codec value equivalence.

    func CodecEquals(
        marshal func(interface{}) ([]byte, error),
        unmarshal func([]byte, interface{}) error,
        opts ...cmp.Option,
    ) Checker

It expects two arguments: a byte slice or a string containing some
codec-marshaled data, and a Go value.

It uses unmarshal to unmarshal the data into an interface{} value.
It marshals the Go value using marshal, then unmarshals the result into
an interface{} value.

It then checks that the two interface{} values are deep-equal to one another,
using CmpEquals(opts) to perform the check.

See JSONEquals for an example of this in use.
*/
package quicktest