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This library is inspired by testify/require, but with a significantly reduced API surface based on empirical use of that package.
It also provides much nicer diff output, eg.
=== RUN TestFail
assert_test.go:14: Expected values to be equal:
assert.Data{
- Str: "foo",
+ Str: "far",
Num: 10,
}
--- FAIL: TestFail (0.00s)
Import then use as assert:
import "github.com/alecthomas/assert/v2"
This library has the following API. For all functions, msgAndArgs is used to
format error messages using the fmt package.
// Equal asserts that "expected" and "actual" are equal using google/go-cmp. // // If they are not, a diff of the Go representation of the values will be displayed. func Equal[T comparable](t testing.TB, expected, actual T, msgAndArgs ...interface{}) // NotEqual asserts that "expected" is not equal to "actual" using google/go-cmp. // // If they are equal the expected value will be displayed. func NotEqual[T comparable](t testing.TB, expected, actual T, msgAndArgs ...interface{}) // Zero asserts that a value is its zero value. func Zero[T comparable](t testing.TB, value T, msgAndArgs ...interface{}) // NotZero asserts that a value is not its zero value. func NotZero[T comparable](t testing.TB, value T, msgAndArgs ...interface{}) // Contains asserts that "haystack" contains "needle". func Contains(t testing.TB, haystack string, needle string, msgAndArgs ...interface{}) // NotContains asserts that "haystack" does not contain "needle". func NotContains(t testing.TB, haystack string, needle string, msgAndArgs ...interface{}) // EqualError asserts that either an error is non-nil and that its message is what is expected, // or that error is nil if the expected message is empty. func EqualError(t testing.TB, err error, errString string, msgAndArgs...interface{}) // Error asserts that an error is not nil. func Error(t testing.TB, err error, msgAndArgs ...interface{}) // NoError asserts that an error is nil. func NoError(t testing.TB, err error, msgAndArgs ...interface{}) // IsError asserts than any error in "err"'s tree matches "target". func IsError(t testing.TB, err, target error, msgAndArgs ...interface{}) // NotIsError asserts than no error in "err"'s tree matches "target". func NotIsError(t testing.TB, err, target error, msgAndArgs ...interface{}) // Panics asserts that the given function panics. func Panics(t testing.TB, fn func(), msgAndArgs ...interface{}) // NotPanics asserts that the given function does not panic. func NotPanics(t testing.TB, fn func(), msgAndArgs ...interface{}) // Compare two values for equality and return true or false. func Compare[T any](t testing.TB, x, y T) bool // True asserts that an expression is true. func True(t testing.TB, ok bool, msgAndArgs ...interface{}) // False asserts that an expression is false. func False(t testing.TB, ok bool, msgAndArgs ...interface{})
Our empircal data of testify usage comes from a monorepo with around 50K lines of tests.
These are the usage counts for all testify functions, normalised to the base
(not Printf()) non-negative(not No(t)?) case for each core function.
2240 Error
1314 Equal
219 True
210 Nil
167 Empty
107 Contains
79 Len
61 False
24 EqualValues
20 EqualError
17 Zero
15 Fail
15 ElementsMatch
9 Panics
7 IsType
6 FileExists
4 JSONEq
3 PanicsWithValue
3 Eventually
The decision for each function was:
Error(t, err)-> frequently used, keepEqual(t, expected, actual)-> frequently used, keep but make type safeTrue(t, expr)-> frequently used, keepFalse(t, expr)-> frequently used, keepEmpty(t, thing)->require.Equal(t, len(thing), 0)Contains(t, haystack string, needle string)- the only variant used in our codebase, keep as concrete typeZero(t, value)-> make type safe, keepPanics(t, f)-> useful, keepEqualError(t, a, b)-> useful, keepNil(t, value)-> frequently used, keep
ElementsMatch(t, a, b)- use peterrk/slices or stdlib sort support once it lands.IsType(t, a, b)->require.Equal(t, reflect.TypeOf(a).String(), reflect.TypeOf(b).String())FileExists()-> very little use, dropJSONEq()-> very little use, dropPanicsWithValue()-> very little use, dropEventually()-> very little use, dropContains(t, haystack []T, needle T)- very little use, replace withContains(t, haystack map[K]V, needle K)- very little use, dropLen(t, v, n)-> cannot be implemented as a single function with genericsEqual(t, len(v), n)EqualValues()-Equal(t, TYPE(a), TYPE(b))Fail()->t.Fatal()