ErrorIs

func ErrorIs(expectedError any) TestDeep

ErrorIs is a smuggler operator. It reports whether any error in an error’s chain matches expectedError.

_, err := os.Open("/unknown/file")
td.Cmp(t, err, os.ErrNotExist)             // fails
td.Cmp(t, err, td.ErrorIs(os.ErrNotExist)) // succeeds

err1 := fmt.Errorf("failure1")
err2 := fmt.Errorf("failure2: %w", err1)
err3 := fmt.Errorf("failure3: %w", err2)
err := fmt.Errorf("failure4: %w", err3)
td.Cmp(t, err, td.ErrorIs(err))  // succeeds
td.Cmp(t, err, td.ErrorIs(err1)) // succeeds
td.Cmp(t, err1, td.ErrorIs(err)) // fails

var cerr myError
td.Cmp(t, err, td.ErrorIs(td.Catch(&cerr, td.String("my error..."))))

td.Cmp(t, err, td.ErrorIs(td.All(
  td.Isa(myError{}),
  td.String("my error..."),
)))

Behind the scene it uses errors.Is function if expectedError is an error and errors.As function if expectedError is a TestDeep operator.

Note that like errors.Is, expectedError can be nil: in this case the comparison succeeds only when got is nil too.

See also CmpError and CmpNoError.

See also ErrorIs godoc.

Example

Base example

	t := &testing.T{}

	err1 := fmt.Errorf("failure1")
	err2 := fmt.Errorf("failure2: %w", err1)
	err3 := fmt.Errorf("failure3: %w", err2)
	err := fmt.Errorf("failure4: %w", err3)

	ok := td.Cmp(t, err, td.ErrorIs(err))
	fmt.Println("error is itself:", ok)

	ok = td.Cmp(t, err, td.ErrorIs(err1))
	fmt.Println("error is also err1:", ok)

	ok = td.Cmp(t, err1, td.ErrorIs(err))
	fmt.Println("err1 is err:", ok)

	// Output:
	// error is itself: true
	// error is also err1: true
	// err1 is err: false

CmpErrorIs shortcut

func CmpErrorIs(t TestingT, got, expectedError any, args ...any) bool

CmpErrorIs is a shortcut for:

td.Cmp(t, got, td.ErrorIs(expectedError), args...)

See above for details.

Returns true if the test is OK, false if it fails.

If t is a *T then its Config field is inherited.

args… are optional and allow to name the test. This name is used in case of failure to qualify the test. If len(args) > 1 and the first item of args is a string and contains a ‘%’ rune then fmt.Fprintf is used to compose the name, else args are passed to fmt.Fprint. Do not forget it is the name of the test, not the reason of a potential failure.

See also CmpErrorIs godoc.

Example

Base example

	t := &testing.T{}

	err1 := fmt.Errorf("failure1")
	err2 := fmt.Errorf("failure2: %w", err1)
	err3 := fmt.Errorf("failure3: %w", err2)
	err := fmt.Errorf("failure4: %w", err3)

	ok := td.CmpErrorIs(t, err, err)
	fmt.Println("error is itself:", ok)

	ok = td.CmpErrorIs(t, err, err1)
	fmt.Println("error is also err1:", ok)

	ok = td.CmpErrorIs(t, err1, err)
	fmt.Println("err1 is err:", ok)

	// Output:
	// error is itself: true
	// error is also err1: true
	// err1 is err: false

T.CmpErrorIs shortcut

func (t *T) CmpErrorIs(got, expectedError any, args ...any) bool

CmpErrorIs is a shortcut for:

t.Cmp(got, td.ErrorIs(expectedError), args...)

See above for details.

Returns true if the test is OK, false if it fails.

See also T.CmpErrorIs godoc.

Example

Base example

	t := td.NewT(&testing.T{})

	err1 := fmt.Errorf("failure1")
	err2 := fmt.Errorf("failure2: %w", err1)
	err3 := fmt.Errorf("failure3: %w", err2)
	err := fmt.Errorf("failure4: %w", err3)

	ok := t.CmpErrorIs(err, err)
	fmt.Println("error is itself:", ok)

	ok = t.CmpErrorIs(err, err1)
	fmt.Println("error is also err1:", ok)

	ok = t.CmpErrorIs(err1, err)
	fmt.Println("err1 is err:", ok)

	// Output:
	// error is itself: true
	// error is also err1: true
	// err1 is err: false