assert

package
v0.151.0 Latest Latest
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 Go to latest Published: May 11, 2024 License: Apache-2.0 Imports: 19 Imported by: 9

README

testcase/assert

This package meant to provide a small and dependency lightweight implementation for common assertion related requirements.

Example:

assert.Should(tb).True(true)
assert.Must(tb).Equal(expected, actual, "error message")
assert.Must(tb).NotEqual(true, false, "exp")
assert.Must(tb).Contain([]int{1, 2, 3}, 3, "exp")
assert.Must(tb).Contain([]int{1, 2, 3}, []int{1, 2}, "exp")
assert.Must(tb).Contain(map[string]int{"The Answer": 42, "oth": 13}, map[string]int{"The Answer": 42}, "exp")

For more examples, check out the example_test.go file.

Documentation

Overview

Example (ConfigureDiffFunc) 
package main

import (
	"fmt"
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	assert.DiffFunc = func(value, othValue any) string {
		return fmt.Sprintf("%#v | %#v", value, othValue)
	}

	var tb testing.TB
	assert.Equal(tb, "foo", "bar")
}

Output:

Index

Examples

Constants

This section is empty.

Variables

View Source 
var DiffFunc diffFn = pp.DiffFormat[any]

DiffFunc is the function that will be used to print out two object if they are not equal. You can use your preferred diff implementation if you are not happy with the pretty print diff format.

Functions

func AnyOf 

func AnyOf(tb testing.TB, blk func(a *A), msg ...Message)

AnyOf is an assertion helper that deems the test successful if any of the declared assertion cases pass. This is commonly used when multiple valid formats are acceptable or when working with a list where any element meeting a certain criteria is considered sufficient.

Example (AnyOfExpectedOutcome) 
package main

import (
	"go.llib.dev/testcase/random"
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	var rnd = random.New(random.CryptoSeed{})

	outcome := rnd.Bool()

	assert.AnyOf(tb, func(a *assert.A) {
		a.Case(func(it assert.It) {
			it.Must.True(outcome)
		})

		a.Case(func(it assert.It) {
			it.Must.False(outcome)
		})
	})
}

Output:
Example (AnyOfTheElement) 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	var list []interface {
		Foo() int
		Bar() bool
		Baz() string
	}
	assert.AnyOf(tb, func(anyOf *assert.A) {
		for _, testingCase := range list {
			anyOf.Case(func(it assert.It) {
				it.Must.True(testingCase.Bar())
			})
		}
	})
}

Output:
Example (FanOutPublishing) 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

type ExamplePublisherEvent struct{ V int }
type ExamplePublisher struct{}

func (ExamplePublisher) Publish(ExamplePublisherEvent)         {}
func (ExamplePublisher) Subscribe(func(ExamplePublisherEvent)) {}
func (ExamplePublisher) Wait()                                 {}
func (ExamplePublisher) Close() error                          { return nil }

func main() {
	var tb testing.TB
	publisher := ExamplePublisher{}
	anyOf := &assert.A{TB: tb, Fail: tb.FailNow}
	for i := 0; i < 42; i++ {
		publisher.Subscribe(func(event ExamplePublisherEvent) {
			anyOf.Case(func(it assert.It) {
				it.Must.Equal(42, event.V)
			})
		})
	}
	publisher.Publish(ExamplePublisherEvent{V: 42})
	publisher.Wait()
	assert.Must(tb).Nil(publisher.Close())
	anyOf.Finish()
}

Output:
Example (ListOfCompositedStructuresWhereOnlyTheEmbededValueIsRelevant) 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	type BigStruct struct {
		ID            string // not relevant for the test
		A, B, C, D, E int    // not relevant data as well
		WrappedStruct struct {
			A, B, C int // relevant data for the test
		}
	}
	anyOf := assert.A{TB: tb, Fail: tb.FailNow}
	for _, v := range []BigStruct{} {
		anyOf.Case(func(it assert.It) {
			it.Must.Equal(42, v.WrappedStruct.A)
			it.Must.Equal(1, v.WrappedStruct.B)
			it.Must.Equal(2, v.WrappedStruct.C)
		})
	}
	anyOf.Finish()
}

Output:
Example (ListOfInterface) 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	type ExampleInterface interface {
		Foo() int
		Bar() bool
		Baz() string
	}
	anyOf := assert.A{TB: tb, Fail: tb.FailNow}
	for _, v := range []ExampleInterface{} {
		anyOf.Case(func(it assert.It) {
			it.Must.True(v.Bar())
		})
	}
	anyOf.Finish()
}

Output:
Example (ListOfStructuresWithIrrelevantValues) 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	type StructWithDynamicValues struct {
		IrrelevantStateValue int // not relevant data for the test
		ImportantValue       int
	}
	anyOf := assert.A{TB: tb, Fail: tb.FailNow}
	for _, v := range []StructWithDynamicValues{} {
		anyOf.Case(func(it assert.It) {
			it.Must.Equal(42, v.ImportantValue)
		})
	}
	anyOf.Finish()
}

Output:
Example (StructWithManyAcceptableState) 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	type ExampleStruct struct {
		Type    string
		A, B, C int
	}
	var es ExampleStruct
	anyOf := assert.A{TB: tb, Fail: tb.FailNow}
	anyOf.Case(func(it assert.It) {
		it.Must.Equal(`foo`, es.Type)
		it.Must.Equal(1, es.A)
		it.Must.Equal(2, es.B)
		it.Must.Equal(3, es.C)
	})
	anyOf.Case(func(it assert.It) {
		it.Must.Equal(`foo`, es.Type)
		it.Must.Equal(3, es.A)
		it.Must.Equal(2, es.B)
		it.Must.Equal(1, es.C)
	})
	anyOf.Case(func(it assert.It) {
		it.Must.Equal(`bar`, es.Type)
		it.Must.Equal(11, es.A)
		it.Must.Equal(12, es.B)
		it.Must.Equal(13, es.C)
	})
	anyOf.Case(func(it assert.It) {
		it.Must.Equal(`baz`, es.Type)
		it.Must.Equal(21, es.A)
		it.Must.Equal(22, es.B)
		it.Must.Equal(23, es.C)
	})
	anyOf.Finish()
}

Output:

func Contain 

func Contain(tb testing.TB, haystack, needle any, msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Must(tb).Contain([]int{1, 2, 3}, 3, "optional assertion explanation")
	assert.Must(tb).Contain([]int{1, 2, 3}, []int{1, 2}, "optional assertion explanation")
	assert.Must(tb).Contain(
		map[string]int{"The Answer": 42, "oth": 13},
		map[string]int{"The Answer": 42},
		"optional assertion explanation")
}

Output:

func ContainExactly 

func ContainExactly[T any](tb testing.TB, v, oth T, msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.ContainExactly(tb, []int{1, 2, 3}, []int{2, 3, 1}, "optional assertion explanation")  // true
	assert.ContainExactly(tb, []int{1, 2, 3}, []int{1, 42, 2}, "optional assertion explanation") // false
}

Output:

func Empty 

func Empty(tb testing.TB, v any, msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Empty(tb, "")       // ok
	assert.Empty(tb, "oh no!") // Fatal
}

Output:

func Equal 

func Equal[T any](tb testing.TB, v, oth T, msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Equal(tb, "a", "a")
	assert.Equal(tb, 42, 42)
	assert.Equal(tb, []int{42}, []int{42})
	assert.Equal(tb, map[int]int{24: 42}, map[int]int{24: 42})
}

Output:

func Error 

func Error(tb testing.TB, err error, msg ...Message)
Example 
package main

import (
	"errors"
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Error(tb, nil)                // fail
	assert.Error(tb, errors.New("boom")) // pass
}

Output:

func ErrorIs 

func ErrorIs(tb testing.TB, err, oth error, msg ...Message)
Example 
package main

import (
	"errors"
	"fmt"
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	actualErr := errors.New("boom")
	assert.ErrorIs(tb, actualErr, errors.New("boom"))                                  // passes for equality
	assert.ErrorIs(tb, fmt.Errorf("wrapped error: %w", actualErr), errors.New("boom")) // passes for wrapped errors
}

Output:

func Eventually 

func Eventually[T time.Duration | int](tb testing.TB, durationOrCount T, blk func(it It))
Example 
package main

import (
	"math/rand"
	"testing"
	"time"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Eventually(tb, time.Second, func(it assert.It) {
		it.Must.True(rand.Intn(1) == 0)
	})
}

Output:

func False 

func False(tb testing.TB, v bool, msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.False(tb, false) // ok
	assert.False(tb, true)  // Fatal
}

Output:

func Match 

func Match[T string | []byte](tb testing.TB, v T, expr string, msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Match(tb, "42", "[0-9]+")
	assert.Match(tb, "forty-two", "[a-z]+")
	assert.Match(tb, []byte("forty-two"), "[a-z]+")
}

Output:

func Nil 

func Nil(tb testing.TB, v any, msg ...Message)
Example 
package main

import (
	"errors"
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Nil(tb, nil)                // ok
	assert.Nil(tb, errors.New("boom")) // Fatal
}

Output:

func NoError 

func NoError(tb testing.TB, err error, msg ...Message)
Example 
package main

import (
	"errors"
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.NoError(tb, nil)                // pass
	assert.NoError(tb, errors.New("boom")) // fail
}

Output:

func NotContain 

func NotContain(tb testing.TB, haystack, v any, msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Must(tb).NotContain([]int{1, 2, 3}, 42)
	assert.Must(tb).NotContain([]int{1, 2, 3}, []int{1, 2, 42})
	assert.Must(tb).NotContain(
		map[string]int{"The Answer": 42, "oth": 13},
		map[string]int{"The Answer": 41})
}

Output:

func NotEmpty 

func NotEmpty(tb testing.TB, v any, msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.NotEmpty(tb, "huh...") // ok
	assert.NotEmpty(tb, "")       // Fatal
}

Output:

func NotEqual 

func NotEqual[T any](tb testing.TB, v, oth T, msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.NotEqual(tb, "a", "b")
	assert.Equal(tb, 13, 42)
}

Output:

func NotMatch 

func NotMatch[T string | []byte](tb testing.TB, v T, expr string, msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.NotMatch(tb, "42", "^[a-z]+")
	assert.NotMatch(tb, "forty-two", "^[0-9]+")
	assert.NotMatch(tb, []byte("forty-two"), "^[0-9]+")
}

Output:

func NotNil 

func NotNil(tb testing.TB, v any, msg ...Message)
Example 
package main

import (
	"errors"
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.NotNil(tb, errors.New("boom")) // ok
	assert.NotNil(tb, nil)                // Fatal
}

Output:

func NotPanic 

func NotPanic(tb testing.TB, blk func(), msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.NotPanic(tb, func() {})                  // ok
	assert.NotPanic(tb, func() { panic("oh no!") }) // Fatal
}

Output:

func NotWithin 

func NotWithin(tb testing.TB, timeout time.Duration, blk func(context.Context), msg ...Message)
Example 
package main

import (
	"context"
	"testing"
	"time"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB

	assert.NotWithin(tb, time.Second, func(ctx context.Context) {
		return // FAIL
	})

	assert.NotWithin(tb, time.Nanosecond, func(ctx context.Context) {
		time.Sleep(time.Second) // OK
	})
}

Output:

func OneOf 

func OneOf[V any](tb testing.TB, vs []V, blk func(t It, got V), msg ...Message)

OneOf function checks a list of values and matches an expectation against each element of the list. If any of the elements pass the assertion, then the assertion helper function does not fail the test.

Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	values := []string{"foo", "bar", "baz"}

	assert.OneOf(tb, values, func(it assert.It, got string) {
		it.Must.Equal("bar", got)
	}, "optional assertion explanation")
}

Output:

func Panic 

func Panic(tb testing.TB, blk func(), msg ...Message) any
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB

	panicValue := assert.Panic(tb, func() { panic("at the disco") }) // ok
	assert.Equal(tb, "some expected panic value", panicValue)

	assert.Panic(tb, func() {}) // Fatal
}

Output:

func Read 

func Read[T string | []byte](tb testing.TB, v T, r io.Reader, msg ...Message)
Example 
package main

import (
	"strings"
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Read(tb, "expected content", strings.NewReader("expected content"))  // pass
	assert.Read(tb, "expected content", strings.NewReader("different content")) // fail
}

Output:

func ReadAll 

func ReadAll(tb testing.TB, r io.Reader, msg ...Message) []byte
Example 
package main

import (
	"errors"
	"strings"
	"testing"
	"testing/iotest"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	content := assert.ReadAll(tb, strings.NewReader("expected content")) // pass
	_ = content
	assert.ReadAll(tb, iotest.ErrReader(errors.New("boom"))) // fail
}

Output:

func RegisterEqual 

func RegisterEqual[T any, FN EqualFunc[T]](fn FN) struct{}

func Sub 

func Sub[T any](tb testing.TB, haystack, needle []T, msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Sub(tb, []int{1, 2, 3}, []int{1, 2}, "optional assertion explanation")
}

Output:

func True 

func True(tb testing.TB, v bool, msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.True(tb, true)  // ok
	assert.True(tb, false) // Fatal
}

Output:

func Within 

func Within(tb testing.TB, timeout time.Duration, blk func(context.Context), msg ...Message)
Example 
package main

import (
	"context"
	"testing"
	"time"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB

	assert.Within(tb, time.Second, func(ctx context.Context) {
		// OK
	})

	assert.Within(tb, time.Nanosecond, func(ctx context.Context) {
		time.Sleep(time.Second)
		// FAIL
	})
}

Output:

Types

type A added in v0.145.0 

type A struct {
	TB   testing.TB
	Fail func()
	// contains filtered or unexported fields
}

A stands for Any Of, an assertion helper that allows you run A.Case assertion blocks, that can fail, as lone at least one of them succeeds. common usage use-cases:

  • list of interface, where test order, or the underlying structure's implementation is irrelevant for the behavior.
  • list of big structures, where not all field value relevant, only a subset, like a structure it wraps under a field.
  • list of structures with fields that has dynamic state values, which is irrelevant for the given test.
  • structure that can have various state scenario, and you want to check all of them, and you expect to find one match with the input.
  • fan out scenario, where you need to check in parallel that at least one of the worker received the event.

func (*A) Case added in v0.145.0 

func (ao *A) Case(blk func(t It))

Case will test a block of assertion that must succeed in order to make A pass. You can have as much A.Case calls as you need, but if any of them pass with success, the rest will be skipped. Using Case is safe for concurrently.

func (*A) Finish added in v0.145.0 

func (ao *A) Finish(msg ...Message)

Finish will check if any of the assertion succeeded.

func (*A) OK added in v0.145.0 

func (ao *A) OK() bool

func (*A) Test added in v0.145.0 

func (ao *A) Test(blk func(t It))

Test is an alias for A.Case

type Asserter 

type Asserter struct {
	TB   testing.TB
	Fail func()
}

func Must 

func Must(tb testing.TB) Asserter
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	// create an assertion helper which will fail the testing context with .Fatal(...) in case of a failed assert.
	assert.Must(tb).True(true)
}

Output:

func Should 

func Should(tb testing.TB) Asserter
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	// create an assertion helper which will fail the testing context with .Error(...) in case of a failed assert.
	assert.Should(tb).True(true)
}

Output:

func (Asserter) AnyOf 

func (a Asserter) AnyOf(blk func(a *A), msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	var list []interface {
		Foo() int
		Bar() bool
		Baz() string
	}
	assert.Must(tb).AnyOf(func(anyOf *assert.A) {
		for _, testingCase := range list {
			anyOf.Case(func(it assert.It) {
				it.Must.True(testingCase.Bar())
			})
		}
	})
}

Output:

func (Asserter) Contain 

func (a Asserter) Contain(haystack, needle any, msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Must(tb).Contain([]int{1, 2, 3}, 3, "optional assertion explanation")
	assert.Must(tb).Contain([]int{1, 2, 3}, []int{1, 2}, "optional assertion explanation")
	assert.Must(tb).Contain(map[string]int{"The Answer": 42, "oth": 13}, map[string]int{"The Answer": 42}, "optional assertion explanation")
}

Output:

func (Asserter) ContainExactly 

func (a Asserter) ContainExactly(v, oth any, msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Must(tb).ContainExactly([]int{1, 2, 3}, []int{2, 3, 1}, "optional assertion explanation")  // true
	assert.Must(tb).ContainExactly([]int{1, 2, 3}, []int{1, 42, 2}, "optional assertion explanation") // false
}

Output:

func (Asserter) Empty 

func (a Asserter) Empty(v any, msg ...Message)

Empty gets whether the specified value is considered empty.

Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB

	assert.Must(tb).Empty([]int{})   // pass
	assert.Must(tb).Empty([]int{42}) // fail

	assert.Must(tb).Empty([42]int{})   // pass
	assert.Must(tb).Empty([42]int{42}) // fail

	assert.Must(tb).Empty(map[int]int{})       // pass
	assert.Must(tb).Empty(map[int]int{42: 24}) // fail

	assert.Must(tb).Empty("")   // pass
	assert.Must(tb).Empty("42") // fail
}

Output:

func (Asserter) Equal 

func (a Asserter) Equal(v, oth any, msg ...Message)

Equal allows you to match if two entity is equal.

if entities are implementing IsEqual/Equal function, then it will be used to check equality between each other.

  • value.IsEqual(oth T) bool
  • value.IsEqual(oth T) (bool, error)
  • value.Equal(oth T) bool
  • value.Equal(oth T) (bool, error)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Must(tb).Equal(true, true, "optional assertion explanation")
}

Output:
Example (IsEqualFunctionThatSupportsErrorReturning) 
package main

import (
	"errors"
	"testing"

	"go.llib.dev/testcase/assert"
)

type ExampleEqualableWithError struct {
	IrrelevantExportedField int
	relevantUnexportedValue int
	IsEqualErr              error
}

func (es ExampleEqualableWithError) IsEqual(oth ExampleEqualableWithError) (bool, error) {
	return es.relevantUnexportedValue == oth.relevantUnexportedValue, es.IsEqualErr
}

func main() {
	var tb testing.TB

	expected := ExampleEqualableWithError{
		IrrelevantExportedField: 42,
		relevantUnexportedValue: 24,
		IsEqualErr:              errors.New("sadly something went wrong"),
	}

	actual := ExampleEqualableWithError{
		IrrelevantExportedField: 42,
		relevantUnexportedValue: 24,
	}

	assert.Must(tb).Equal(expected, actual) // fails because the error returned from the IsEqual function.
}

Output:
Example (WithEqualMethod) 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

type ExampleEqualableWithEqual struct {
	IrrelevantExportedField int
	relevantUnexportedValue int
}

func (es ExampleEqualableWithEqual) IsEqual(oth ExampleEqualableWithEqual) bool {
	return es.relevantUnexportedValue == oth.relevantUnexportedValue
}

func main() {
	var tb testing.TB

	expected := ExampleEqualableWithEqual{
		IrrelevantExportedField: 42,
		relevantUnexportedValue: 24,
	}

	actual := ExampleEqualableWithEqual{
		IrrelevantExportedField: 4242,
		relevantUnexportedValue: 24,
	}

	assert.Must(tb).Equal(expected, actual) // passes as by IsEqual terms the two value is equal
}

Output:
Example (WithIsEqualMethod) 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

type ExampleEqualableWithIsEqual struct {
	IrrelevantExportedField int
	relevantUnexportedValue int
}

func (es ExampleEqualableWithIsEqual) IsEqual(oth ExampleEqualableWithIsEqual) bool {
	return es.relevantUnexportedValue == oth.relevantUnexportedValue
}

func main() {
	var tb testing.TB

	expected := ExampleEqualableWithIsEqual{
		IrrelevantExportedField: 42,
		relevantUnexportedValue: 24,
	}

	actual := ExampleEqualableWithIsEqual{
		IrrelevantExportedField: 4242,
		relevantUnexportedValue: 24,
	}

	assert.Must(tb).Equal(expected, actual) // passes as by IsEqual terms the two value is equal
}

Output:

func (Asserter) Error 

func (a Asserter) Error(err error, msg ...Message)
Example 
package main

import (
	"errors"
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	asserter := assert.Should(tb)
	asserter.Error(nil)                // fail
	asserter.Error(errors.New("boom")) // pass
}

Output:

func (Asserter) ErrorIs 

func (a Asserter) ErrorIs(err, oth error, msg ...Message)

ErrorIs allow you to assert an error value by an expectation. ErrorIs allow asserting an error regardless if it's wrapped or not. Suppose the implementation of the test subject later changes by wrap errors to add more context to the return error.

Example 
package main

import (
	"errors"
	"fmt"
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB

	actualErr := errors.New("boom")
	assert.Must(tb).ErrorIs(errors.New("boom"), actualErr)                                  // passes for equality
	assert.Must(tb).ErrorIs(errors.New("boom"), fmt.Errorf("wrapped error: %w", actualErr)) // passes for wrapped errors
}

Output:

func (Asserter) Eventually added in v0.144.0 

func (a Asserter) Eventually(durationOrCount any, blk func(it It))
Example 
package main

import (
	"math/rand"
	"testing"
	"time"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Must(tb).Eventually(time.Minute, func(it assert.It) {
		it.Must.True(rand.Intn(1) == 0)
	})
}

Output:

func (Asserter) False 

func (a Asserter) False(v bool, msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Must(tb).False(false, "optional assertion explanation")
}

Output:

func (Asserter) Match 

func (a Asserter) Match(v, expr string, msg ...Message)

Match will match an expression against a given value. Match will fail for both receiving an invalid expression or having the value not matched by the expression. If the expression is invalid, test will fail early, regardless if Should or Must was used.

Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Must(tb).Match("42", "[0-9]+")
	assert.Must(tb).Match("forty-two", "[a-z]+")
}

Output:

func (Asserter) Nil 

func (a Asserter) Nil(v any, msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Must(tb).Nil(nil, "optional assertion explanation")
}

Output:

func (Asserter) NoError 

func (a Asserter) NoError(err error, msg ...Message)
Example 
package main

import (
	"errors"
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	asserter := assert.Should(tb)
	asserter.NoError(nil)                // pass
	asserter.NoError(errors.New("boom")) // fail
}

Output:

func (Asserter) NotContain 

func (a Asserter) NotContain(haystack, v any, msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Must(tb).NotContain([]int{1, 2, 3}, 42, "optional assertion explanation")
	assert.Must(tb).NotContain([]int{1, 2, 3}, []int{42}, "optional assertion explanation")
	assert.Must(tb).NotContain(map[string]int{"The Answer": 42, "oth": 13}, map[string]int{"The Answer": 13}, "optional assertion explanation")
}

Output:

func (Asserter) NotEmpty 

func (a Asserter) NotEmpty(v any, msg ...Message)

NotEmpty gets whether the specified value is considered empty.

Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB

	assert.Must(tb).NotEmpty([]int{42}, "optional assertion explanation")

	assert.Must(tb).NotEmpty([]int{})   // fail
	assert.Must(tb).NotEmpty([]int{42}) // pass

	assert.Must(tb).NotEmpty([42]int{})   // fail
	assert.Must(tb).NotEmpty([42]int{42}) // pass

	assert.Must(tb).NotEmpty(map[int]int{})       // fail
	assert.Must(tb).NotEmpty(map[int]int{42: 24}) // pass

	assert.Must(tb).NotEmpty("")   // fail
	assert.Must(tb).NotEmpty("42") // pass
}

Output:

func (Asserter) NotEqual 

func (a Asserter) NotEqual(v, oth any, msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Must(tb).NotEqual(true, false, "optional assertion explanation")
}

Output:

func (Asserter) NotMatch 

func (a Asserter) NotMatch(v, expr string, msg ...Message)

NotMatch will check if an expression is not matching a given value. NotMatch will fail the test early for receiving an invalid expression.

Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Must(tb).NotMatch("42", "^[a-z]+")
	assert.Must(tb).NotMatch("forty-two", "^[0-9]+")
}

Output:

func (Asserter) NotNil 

func (a Asserter) NotNil(v any, msg ...Message)
Example 
package main

import (
	"errors"
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Must(tb).NotNil(errors.New("42"), "optional assertion explanation")
}

Output:

func (Asserter) NotPanic 

func (a Asserter) NotPanic(blk func(), msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Must(tb).NotPanic(func() { /* no boom */ }, "optional assertion explanation")
}

Output:

func (Asserter) NotWithin 

func (a Asserter) NotWithin(timeout time.Duration, blk func(context.Context), msg ...Message)
Example 
package main

import (
	"context"
	"testing"
	"time"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	a := assert.Must(tb)

	a.NotWithin(time.Second, func(ctx context.Context) {
		return // FAIL
	})

	a.NotWithin(time.Nanosecond, func(ctx context.Context) {
		time.Sleep(time.Second) // OK
	})
}

Output:

func (Asserter) OneOf added in v0.145.0 

func (a Asserter) OneOf(values any, blk any, msg ...Message)

OneOf evaluates whether at least one element within the given values meets the conditions set in the assertion block.

Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	values := []string{"foo", "bar", "baz"}

	assert.Must(tb).OneOf(values, func(it assert.It, got string) {
		it.Must.Equal("bar", got)
	}, "optional assertion explanation")
}

Output:

func (Asserter) Panic 

func (a Asserter) Panic(blk func(), msg ...Message) any
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Must(tb).Panic(func() { panic("boom") }, "optional assertion explanation")
}

Output:

func (Asserter) Read 

func (a Asserter) Read(v any, r io.Reader, msg ...Message)
Example 
package main

import (
	"strings"
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	must := assert.Must(tb)
	must.Read("expected content", strings.NewReader("expected content"))  // pass
	must.Read("expected content", strings.NewReader("different content")) // fail
}

Output:

func (Asserter) ReadAll 

func (a Asserter) ReadAll(r io.Reader, msg ...Message) []byte
Example 
package main

import (
	"errors"
	"strings"
	"testing"
	"testing/iotest"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	must := assert.Must(tb)
	content := must.ReadAll(strings.NewReader("expected content")) // pass
	_ = content
	must.ReadAll(iotest.ErrReader(errors.New("boom"))) // fail
}

Output:

func (Asserter) Sub 

func (a Asserter) Sub(slice, sub any, msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Must(tb).Sub([]int{1, 2, 3}, 3, "optional assertion explanation")
	assert.Must(tb).Sub([]int{1, 2, 3}, []int{1, 2}, "optional assertion explanation")
}

Output:

func (Asserter) True 

func (a Asserter) True(v bool, msg ...Message)
Example 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.Must(tb).True(true, "optional assertion explanation")
}

Output:

func (Asserter) Within 

func (a Asserter) Within(timeout time.Duration, blk func(context.Context), msg ...Message)
Example 
package main

import (
	"context"
	"testing"
	"time"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	a := assert.Must(tb)

	a.Within(time.Second, func(ctx context.Context) {
		// OK
	})

	a.Within(time.Nanosecond, func(ctx context.Context) {
		time.Sleep(time.Second)
		// FAIL
	})
}

Output:

type EqualFunc 

type EqualFunc[T any] interface {
	func(v1, v2 T) (bool, error) |
		func(v1, v2 T) bool
}

type It 

type It struct {
	testing.TB
	// Must Asserter will use FailNow on a failed assertion.
	// This will make test exit early on.
	Must Asserter
	// Should Asserter's will allow to continue the test scenario,
	// but mark test failed on a failed assertion.
	Should Asserter
}

func MakeIt 

func MakeIt(tb testing.TB) It

type Message 

type Message string
Example 
package main

import (
	"go.llib.dev/testcase/assert"
	"testing"
)

func main() {
	var tb testing.TB

	assert.True(tb, true, "this is a const which is interpreted as assertion.Message")
}

Output:

func MessageF added in v0.147.2 

func MessageF(format string, args ...any) Message

type Retry added in v0.144.0 

type Retry struct{ Strategy RetryStrategy }

Retry Automatically retries operations whose failure is expected under certain defined conditions. This pattern enables fault-tolerance.

A common scenario where using Retry will benefit you is testing concurrent operations. Due to the nature of async operations, one might need to wait and observe the system with multiple tries before the outcome can be seen.

Example 
package main

import (
	"math/rand"
	"testing"
	"time"

	"go.llib.dev/testcase/assert"
)

func main() {
	waiter := assert.Waiter{
		WaitDuration: time.Millisecond,
		Timeout:      time.Second,
	}
	w := assert.Retry{Strategy: waiter}

	var t *testing.T
	// will attempt to wait until assertion block passes without a failing testCase result.
	// The maximum time it is willing to wait is equal to the wait timeout duration.
	// If the wait timeout reached, and there was no passing assertion run,
	// the last failed assertion history is replied to the received testing.TB
	//   In this case the failure would be replied to the *testing.T.
	w.Assert(t, func(it assert.It) {
		if rand.Intn(1) == 0 {
			it.Fatal(`boom`)
		}
	})
}

Output:
Example (AsContextOption) 
package main

import (
	"testing"

	"go.llib.dev/testcase"
	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	s := testcase.NewSpec(tb)

	s.Test(`flaky`, func(t *testcase.T) {
		// flaky test content here
	}, testcase.Flaky(assert.RetryCount(42)))
}

Output:
Example (ByCount) 
package main

import (
	"math/rand"
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	r := assert.Retry{Strategy: assert.RetryCount(42)}

	var t *testing.T
	r.Assert(t, func(it assert.It) {
		if rand.Intn(1) == 0 {
			it.Fatal(`boom`)
		}
	})
}

Output:
Example (ByCustomRetryStrategy) 
package main

import (
	"math/rand"
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	// this approach ideal if you need to deal with asynchronous systems
	// where you know that if a workflow process ended already,
	// there is no point in retrying anymore the assertion.

	while := func(isFailed func() bool) {
		for isFailed() {
			// just retry while assertion is failed
			// could be that assertion will be failed forever.
			// Make sure the assertion is not stuck in a infinite loop.
		}
	}

	r := assert.Retry{Strategy: assert.RetryStrategyFunc(while)}

	var t *testing.T
	r.Assert(t, func(it assert.It) {
		if rand.Intn(1) == 0 {
			it.Fatal(`boom`)
		}
	})
}

Output:
Example (ByTimeout) 
package main

import (
	"math/rand"
	"testing"
	"time"

	"go.llib.dev/testcase/assert"
)

func main() {
	r := assert.Retry{Strategy: assert.Waiter{
		WaitDuration: time.Millisecond,
		Timeout:      time.Second,
	}}

	var t *testing.T
	r.Assert(t, func(it assert.It) {
		if rand.Intn(1) == 0 {
			it.Fatal(`boom`)
		}
	})
}

Output:
Example (Count) 
package main

import (
	"go.llib.dev/testcase/assert"
)

func main() {
	_ = assert.Retry{Strategy: assert.RetryCount(42)}
}

Output:

func MakeRetry added in v0.144.0 

func MakeRetry[T time.Duration | int](durationOrCount T) Retry
Example 
package main

import (
	"testing"
	"time"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.MakeRetry(5*time.Second).Assert(tb, func(it assert.It) {
		// use "it" as you would tb, but if the test fails with "it"
		// then the function block will be retried until the allowed time duration, which is one minute in this case.
	})
}

Output:
Example (ByCount) 
package main

import (
	"testing"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.MakeRetry(3 /* times */).Assert(tb, func(it assert.It) {
		// use "it" as you would tb, but if the test fails with "it"
		// it will be retried 3 times as specified above as argument.
	})
}

Output:
Example (ByTimeout) 
package main

import (
	"testing"
	"time"

	"go.llib.dev/testcase/assert"
)

func main() {
	var tb testing.TB
	assert.MakeRetry(time.Minute /* times */).Assert(tb, func(it assert.It) {
		// use "it" as you would tb, but if the test fails with "it"
		// then the function block will be retried until the allowed time duration, which is one minute in this case.
	})
}

Output:

func (Retry) Assert added in v0.144.0 

func (r Retry) Assert(tb testing.TB, blk func(it It))

Assert will attempt to assert with the assertion function block multiple times until the expectations in the function body met. In case expectations are failed, it will retry the assertion block using the RetryStrategy. The last failed assertion results would be published to the received testing.TB. Calling multiple times the assertion function block content should be a safe and repeatable operation.

type RetryStrategy 

type RetryStrategy interface {
	// While implements the retry strategy looping part.
	// Depending on the outcome of the condition,
	// the RetryStrategy can decide whether further iterations can be done or not
	While(condition func() bool)
}

func RetryCount 

func RetryCount(times int) RetryStrategy

type RetryStrategyFunc 

type RetryStrategyFunc func(condition func() bool)

func (RetryStrategyFunc) While 

func (fn RetryStrategyFunc) While(condition func() bool)

type Waiter 

type Waiter struct {
	// WaitDuration is the time how lone Waiter.Wait should wait between attempting a new retry during Waiter.While.
	WaitDuration time.Duration
	// Timeout is used to calculate the deadline for the Waiter.While call.
	// If the retry takes longer than the Timeout, the retry will be cancelled.
	Timeout time.Duration
}

Waiter is a component that waits for a time, event, or opportunity.

func (Waiter) Wait 

func (w Waiter) Wait()

Wait will attempt to wait a bit and leave breathing space for other goroutines to steal processing time. It will also attempt to schedule other goroutines.

Example 
package main

import (
	"time"

	"go.llib.dev/testcase/assert"
)

func main() {
	w := assert.Waiter{WaitDuration: time.Millisecond}

	w.Wait() // will wait 1 millisecond and attempt to schedule other go routines
}

Output:

func (Waiter) While 

func (w Waiter) While(condition func() bool)

While will wait until a condition met, or until the wait timeout. By default, if the timeout is not defined, it just attempts to execute the condition once. Calling multiple times the condition function should be a safe operation.

Example 
package main

import (
	"math/rand"
	"time"

	"go.llib.dev/testcase/assert"
)

func main() {
	w := assert.Waiter{
		WaitDuration: time.Millisecond,
		Timeout:      time.Second,
	}

	// will attempt to wait until condition returns false.
	// The maximum time it is willing to wait is equal to the wait timeout duration.
	w.While(func() bool {
		return rand.Intn(1) == 0
	})
}

Output:

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