is Testing Framework

To use is, you must first create a new instance of the testing helper using is.New(t) or is.NewRelaxed(t). You should always start your tests with this initialization.

There are two modes of operation:

1. Strict Mode (is.New): When an assertion fails, it calls t.FailNow(), which immediately aborts the current test. This is the recommended mode for most tests.
2. Relaxed Mode (is.NewRelaxed): When an assertion fails, it calls t.Fail(), allowing the test to continue executing. This is useful if you want to report multiple failures within a single test function.

func Test(t *testing.T) {
	// always start tests with this
	is := is.New(t)

	// ... assertions ...
}

The is package supports disabling colors. This can be controlled via:

1. The -nocolor command-line flag.
2. The NO_COLOR environment variable (following the no-color.org standard).
3. The IS_NO_COLOR environment variable (set to a boolean value like true or false).

The Fail method immediately reports a failure.

• In Strict Mode (is.New), the test will abort.
• In Relaxed Mode (is.NewRelaxed), the test will continue executing but will still be marked as failed.

func (is *I) Fail()

The Equal method asserts that two values a and b are equal. It uses reflect.DeepEqual for comparison. If the assertion fails, it outputs the values and their types. If one of the values is nil, it specifically reports <nil>.

Note on Comments: You can add a description to your failure output by adding a Go comment on the same line as the assertion.

func (is *I) Equal(a, b interface{})

When using Go's t.Run for subtests, you should create a new is instance inside the subtest function to ensure failures are correctly scoped to that subtest.

func Test(t *testing.T) {
	is := is.New(t)
	t.Run("sub", func(t *testing.T) {
		is := is.New(t)
		// test logic here
	})
}

The NoErr method asserts that the provided error is nil. If an error is present, it logs the error message prefixed with err: .

func (is *I) NoErr(err error)

The True method asserts that the provided boolean expression is true. If the expression is false, it reports not true: $ARGS, where $ARGS is expanded to the actual arguments used in the call.

func (is *I) True(expression bool)

The is package requires an object that implements the T interface to report failures. The standard *testing.T from the Go library implements this interface.

type T interface {
	// Fail indicates that the test has failed but
	// allowed execution to continue.
	Fail()
	// FailNow indicates that the test has failed and
	// aborts the test.
	FailNow()
}