errdiff

Documentation

Overview

Package errdiff makes it easy to compare Error by code, substring or exact match in tests.

Similar in intended usage to messagediff.Diff and pretty.Compare, particularly in table-driven tests.

Example usage:

testCases := []struct {
	...
	wantSubstring string
}{
	// Success
	{...},
	// Failures
	{..., wantSubstring: "failed"},
	{..., wantSubstring: "too many users"},
}
for _, c := range testCases {
	got, err := fn(...)
	if diff := errdiff.Substring(err, c.wantSubstring); diff != "" {
		t.Errorf("fn() %v", diff)
		continue
	}
	...
}

The generic function Check may be used in place of Code or Substring or when comparing against another error or for simple existance of an error:

testCases := []struct {
	...
	err interface{}
}{
	// Success
	{...},
	// Failures
	{..., err: io.EOF},  // An explicit error
	{..., err: "my expected error string"},  // contains text
	{..., err: true}, // expect an error, don't care what
}
for _, c := range testCases {
	got, err := fn(...)
	if diff := errdiff.Check(err, c.err); diff != "" {
		t.Errorf("fn() %v", diff)
		continue
	}
	...

Index

• func Check(got error, want interface{}) string
• func Substring(got error, want string) string
• func Text(got error, want string) string

Functions

func Check

func Check(got error, want interface{}) string

Check returns a message describing the difference between the error err and want. If want is a codes.Code, this function is the same as Code. If want is a string, this function is the same as Substring. If want is an error, this is essentially the same as ExactTextCompare(got, w.Error()). If want is a bool, err is simply tested for existance (want of true means an error is wanted).

func Substring

func Substring(got error, want string) string

Substring returns a message describing the difference between the error text and the desired input. want="" indicates that no error is expected.

func Text

func Text(got error, want string) string

Text returns a message describing the difference between the error text and the desired input. want="" indicates that no error is expected.