Assert

Fork of the very nice testza with some modifications. This version uses comparable from newer versions of golang and drops the Assert prefix from the functions. It also runs t.FailNow() for assert.NoError, and introduces json comparisons.

---

Get The Module | Documentation

---

Installation

# Execute this command inside your project
go get github.com/chalk-ai/assert

Description

assert is a full-featured testing framework for Go. It integrates with the default test runner, so you can use it with the standard go test tool. assert contains easy-to-use methods, like assertions, output capturing, fuzzing, and much more.

The main goal of assert is to provide an easy and fun experience writing tests and providing a nice, user-friendly output.

Features

Feature	Description
Assertions	Assertions allow you to quickly check objects for expected values.
Fuzzing	Fuzzing allows you to check functions against sets of generated input parameters. A couple lines of test code can run thousands of sanity tests.
Output Capture	Capture and validate output written to the terminal. Perfect for CLI tools.
Snapshots	Snapshot objects between test runs, to ensure a consistent behaviour.
Clean Output	Clean and colorful output provides you the needed details in an easy-to-understand format.
System Information	assert prints information about the system on startup. You can quickly figure out what's wrong, when a user submits an issue.
Well Documented	Every function of assert is well documented and contains an example to make usage super easy.
Customizable	assert features customizable settings, if you want to change something.
Test flags	You can configure assert via flags too! That makes it super simple to change test runs, or output, without touching code!

Getting Started

See the examples below for a quick introduction!

// --- Some Examples ---

// - Some assertions -
assert.AssertTrue(t, true) // -> Pass
assert.AssertNoError(t, err) // -> Pass
assert.AssertEqual(t, object, object) // -> Pass
// ...

// - Testing console output -
// Test the output of your CLI tool easily!
terminalOutput, _ := assert.CaptureStdout(func(w io.Writer) error {fmt.Println("Hello"); return nil})
asssert.AssertEqual(t, terminalOutput, "Hello\n") // -> Pass

// - Fuzzing -
// Testing a function that accepts email addresses as a parameter:

// Testset of many different email addresses
emailAddresses := assert.FuzzStringEmailAddresses()

// Run a test for every string in the test set
assert.FuzzStringRunTests(t, emailAddresses, func(t *testing.T, index int, str string) {
  user, domain, err := internal.ParseEmailAddress(str) // Use your function
  assert.AssertNoError(t, err) // Assert that your function does not return an error
  assert.AssertNotZero(t, user) // Assert that the user is returned
  assert.AssertNotZero(t, domain) // Assert that the domain is returned
})

// And that's just a few examples of what you can do with assert!

📚 Documentation

Module	Methods
Settings	Click to expand SetColorsEnabled SetDiffContextLines SetLineNumbersEnabled SetRandomSeed SetShowStartupMessage
Assert	Click to expand AssertCompletesIn AssertContains AssertDecreasing AssertDirEmpty AssertDirExists AssertDirNotEmpty AssertEqual AssertEqualValues AssertErrorIs AssertFalse AssertFileExists AssertGreater AssertGreaterOrEqual AssertImplements AssertInRange AssertIncreasing AssertKindOf AssertLen AssertLess AssertLessOrEqual AssertNil AssertNoDirExists AssertNoError AssertNoFileExists AssertNoSubset AssertNotCompletesIn AssertNotContains AssertNotEqual AssertNotEqualValues AssertNotErrorIs AssertNotImplements AssertNotInRange AssertNotKindOf AssertNotNil AssertNotNumeric AssertNotPanics AssertNotRegexp AssertNotSameElements AssertNotUnique AssertNotZero AssertNumeric AssertPanics AssertRegexp AssertSameElements AssertSubset AssertTestFails AssertTrue AssertUnique AssertZero
Capture	Click to expand CaptureStderr CaptureStdout CaptureStdoutAndStderr
Fuzz Utils	Click to expand FuzzUtilDistinctSet FuzzUtilLimitSet FuzzUtilMergeSets FuzzUtilModifySet FuzzUtilRunTests
Fuzz Booleans	Click to expand FuzzBoolFull
Fuzz Strings	Click to expand FuzzStringEmailAddresses FuzzStringEmpty FuzzStringFull FuzzStringGenerateRandom FuzzStringHtmlTags FuzzStringLong FuzzStringNumeric FuzzStringUsernames
Fuzz Float64s	Click to expand FuzzFloat64Full FuzzFloat64GenerateRandomNegative FuzzFloat64GenerateRandomPositive FuzzFloat64GenerateRandomRange
Fuzz Integers	Click to expand FuzzIntFull FuzzIntGenerateRandomNegative FuzzIntGenerateRandomPositive FuzzIntGenerateRandomRange
Snapshot	Click to expand SnapshotCreate SnapshotCreateOrValidate SnapshotValidate

Assert

AssertCompletesIn

func AssertCompletesIn(t testRunner, duration time.Duration, f func(), msg ...any)

AssertCompletesIn asserts that a function completes in a given time. Use this function to test that functions do not take too long to complete.

NOTE: Every system takes a different amount of time to complete a function. Do not set the duration too low, if you want consistent results.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertCompletesIn(t, 2 * time.Second, func() {
	// some code that should take less than 2 seconds...
}) // => PASS

AssertContains

func AssertContains(t testRunner, object, element any, msg ...any)

AssertContains asserts that a string/list/array/slice/map contains the specified element.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertContains(t, []int{1,2,3}, 2)
assert.AssertContains(t, []string{"Hello", "World"}, "World")
assert.AssertContains(t, "Hello, World!", "World")

AssertDecreasing

func AssertDecreasing(t testRunner, object any, msg ...any)

AssertDecreasing asserts that the values in a slice are decreasing. the test fails if the values are not in a slice or if the values are not comparable.

Valid input kinds are: []int, []int8, []int16, []int32, []int64, []uint, []uint8, []uint16, []uint32, []uint64, []float32, []float64.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertDecreasing(t, []int{1000, 137, 2, 1})
assert.AssertDecreasing(t, []float32{13.5, 7, 0.1, -10.3})

AssertDirEmpty

func AssertDirEmpty(t testRunner, dir string, msg ...any)

AssertDirEmpty asserts that a directory is empty. The test will pass when the directory is empty or does not exist.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertDirEmpty(t, "FolderName")

AssertDirExists

func AssertDirExists(t testRunner, dir string, msg ...any)

AssertDirExists asserts that a directory exists. The test will pass when the directory exists, and it's visible to the current user. The test will fail, if the path points to a file.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertDirExists(t, "FolderName")

AssertDirNotEmpty

func AssertDirNotEmpty(t testRunner, dir string, msg ...any)

AssertDirNotEmpty asserts that a directory is not empty The test will pass when the directory is not empty and will fail if the directory does not exist.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertDirNotEmpty(t, "FolderName")

AssertEqual

func AssertEqual(t testRunner, expected any, actual any, msg ...any)

AssertEqual asserts that two objects are equal.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertEqual(t, "Hello, World!", "Hello, World!")
assert.AssertEqual(t, true, true)

AssertEqualValues

func AssertEqualValues(t testRunner, expected any, actual any, msg ...any)

AssertEqualValues asserts that two objects have equal values. The order of the values is also validated.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertEqualValues(t, []string{"Hello", "World"}, []string{"Hello", "World"})
assert.AssertEqualValues(t, []int{1,2}, []int{1,2})
assert.AssertEqualValues(t, []int{1,2}, []int{2,1}) // FAILS (wrong order)

Comparing struct values:

person1 := Person{
  Name:   "Marvin Wendt",
  Age:    20,
  Gender: "male",
}

person2 := Person{
  Name:   "Marvin Wendt",
  Age:    20,
  Gender: "male",
}

assert.AssertEqualValues(t, person1, person2)

AssertErrorIs

func AssertErrorIs(t testRunner, err, target error, msg ...any)

AssertErrorIs asserts that target is inside the error chain of err.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

var testErr = errors.New("hello world")
var testErrWrapped = fmt.Errorf("test err: %w", testErr)
assert.AssertErrorIs(t, testErrWrapped ,testErr)

AssertFalse

func AssertFalse(t testRunner, value any, msg ...any)

AssertFalse asserts that an expression or object resolves to false.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertFalse(t, false)
assert.AssertFalse(t, 1 == 2)
assert.AssertFalse(t, 2 != 2)
assert.AssertFalse(t, 1 > 5 && 4 < 0)

AssertFileExists

func AssertFileExists(t testRunner, file string, msg ...any)

AssertFileExists asserts that a file exists.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertFileExists(t, "./test.txt")
assert.AssertFileExists(t, "./config.yaml", "the config file is missing")

AssertGreater

func AssertGreater(t testRunner, object1, object2 any, msg ...any)

AssertGreater asserts that the first object is greater than the second.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertGreater(t, 5, 1)
assert.AssertGreater(t, 10, -10)

AssertGreaterOrEqual

func AssertGreaterOrEqual(t testRunner, object1, object2 interface{}, msg ...interface{})

AssertGreaterOrEqual asserts that the first object is greater than or equal to the second.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertGreaterOrEqual(t, 5, 1)
assert.AssertGreaterOrEqual(t, 10, -10)

assert.AssertGreaterOrEqual(t, 10, 10)

AssertImplements

func AssertImplements(t testRunner, interfaceObject, object any, msg ...any)

AssertImplements asserts that an objects implements an interface.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertImplements(t, (*YourInterface)(nil), new(YourObject))
assert.AssertImplements(t, (*fmt.Stringer)(nil), new(types.Const)) => pass

AssertInRange

func AssertInRange[T number](t testRunner, value T, min T, max T, msg ...any)

AssertInRange asserts that the value is in the range.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertInRange(t, 5, 1, 10)

AssertIncreasing

func AssertIncreasing(t testRunner, object any, msg ...any)

AssertIncreasing asserts that the values in a slice are increasing. the test fails if the values are not in a slice or if the values are not comparable.

Valid input kinds are: []int, []int8, []int16, []int32, []int64, []uint, []uint8, []uint16, []uint32, []uint64, []float32, []float64.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertIncreasing(t, []int{1, 2, 137, 1000})
assert.AssertIncreasing(t, []float32{-10.3, 0.1, 7, 13.5})

AssertKindOf

func AssertKindOf(t testRunner, expectedKind reflect.Kind, object any, msg ...any)

AssertKindOf asserts that the object is a type of kind exptectedKind.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertKindOf(t, reflect.Slice, []int{1,2,3})
assert.AssertKindOf(t, reflect.Slice, []string{"Hello", "World"})
assert.AssertKindOf(t, reflect.Int, 1337)
assert.AssertKindOf(t, reflect.Bool, true)
assert.AssertKindOf(t, reflect.Map, map[string]bool{})

AssertLen

func AssertLen(t testRunner, object any, length int, msg ...any)

AssertLen asserts that the length of an object is equal to the given length.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertLen(t, "abc", 3)
assert.AssertLen(t, "Assert", 6)
assert.AssertLen(t, []int{1, 2, 1337, 25}, 4)
assert.AssertLen(t, map[string]int{"asd": 1, "test": 1337}, 2)

AssertLess

func AssertLess(t testRunner, object1, object2 any, msg ...any)

AssertLess asserts that the first object is less than the second.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertLess(t, 1, 5)
assert.AssertLess(t, -10, 10)

AssertLessOrEqual

func AssertLessOrEqual(t testRunner, object1, object2 interface{}, msg ...interface{})

AssertLessOrEqual asserts that the first object is less than or equal to the second.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertLessOrEqual(t, 1, 5)
assert.AssertLessOrEqual(t, -10, 10)
assert.AssertLessOrEqual(t, 1, 1)

AssertNil

func AssertNil(t testRunner, object any, msg ...any)

AssertNil asserts that an object is nil.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertNil(t, nil)

AssertNoDirExists

func AssertNoDirExists(t testRunner, dir string, msg ...any)

AssertNoDirExists asserts that a directory does not exists. The test will pass, if the path points to a file, as a directory with the same name, cannot exist.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertNoDirExists(t, "FolderName")

AssertNoError

func AssertNoError(t testRunner, err error, msg ...any)

AssertNoError asserts that an error is nil.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

err := nil
assert.AssertNoError(t, err)

AssertNoFileExists

func AssertNoFileExists(t testRunner, file string, msg ...any)

AssertNoSubset

func AssertNoSubset(t testRunner, list any, subset any, msg ...any)

AssertNoSubset asserts that the second parameter is not a subset of the list. The order is irrelevant.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertNoSubset(t, []int{1, 2, 3}, []int{1, 7})
assert.AssertNoSubset(t, []string{"Hello", "World", "Test"}, []string{"Test", "John"})

AssertNotCompletesIn

func AssertNotCompletesIn(t testRunner, duration time.Duration, f func(), msg ...any)

AssertNotCompletesIn asserts that a function does not complete in a given time. Use this function to test that functions do not complete to quickly. For example if your database connection completes in under a millisecond, there might be something wrong.

NOTE: Every system takes a different amount of time to complete a function. Do not set the duration too high, if you want consistent results.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertNotCompletesIn(t, 2 * time.Second, func() {
	// some code that should take more than 2 seconds...
	time.Sleep(3 * time.Second)
}) // => PASS

AssertNotContains

func AssertNotContains(t testRunner, object, element any, msg ...any)

AssertNotContains asserts that a string/list/array/slice/map does not contain the specified element.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertNotContains(t, []string{"Hello", "World"}, "Spaceship")
assert.AssertNotContains(t, "Hello, World!", "Spaceship")

AssertNotEqual

func AssertNotEqual(t testRunner, expected any, actual any, msg ...any)

AssertNotEqual asserts that two objects are not equal.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertNotEqual(t, true, false)
assert.AssertNotEqual(t, "Hello", "World")

AssertNotEqualValues

func AssertNotEqualValues(t testRunner, expected any, actual any, msg ...any)

AssertNotEqualValues asserts that two objects do not have equal values.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertNotEqualValues(t, []int{1,2}, []int{3,4})

Comparing struct values:

person1 := Person{
  Name:   "Marvin Wendt",
  Age:    20,
  Gender: "male",
}

person2 := Person{
  Name:   "Marvin Wendt",
  Age:    20,
  Gender: "female", // <-- CHANGED
}

assert.AssertNotEqualValues(t, person1, person2)

AssertNotErrorIs

func AssertNotErrorIs(t testRunner, err, target error, msg ...any)

AssertNotErrorIs

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

var testErr = errors.New("hello world")
var test2Err = errors.New("hello world 2")
var testErrWrapped = fmt.Errorf("test err: %w", testErr)
assert.AssertNotErrorIs(t, testErrWrapped, test2Err)

AssertNotImplements

func AssertNotImplements(t testRunner, interfaceObject, object any, msg ...any)

AssertNotImplements asserts that an object does not implement an interface.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertNotImplements(t, (*YourInterface)(nil), new(YourObject))
assert.AssertNotImplements(t, (*fmt.Stringer)(nil), new(types.Const)) => fail, because types.Const does implement fmt.Stringer.

AssertNotInRange

func AssertNotInRange[T number](t testRunner, value T, min T, max T, msg ...any)

AssertNotInRange asserts that the value is not in the range.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertNotInRange(t, 5, 1, 10)

AssertNotKindOf

func AssertNotKindOf(t testRunner, kind reflect.Kind, object any, msg ...any)

AssertNotKindOf asserts that the object is not a type of kind kind.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertNotKindOf(t, reflect.Slice, "Hello, World")
assert.AssertNotKindOf(t, reflect.Slice, true)
assert.AssertNotKindOf(t, reflect.Int, 13.37)
assert.AssertNotKindOf(t, reflect.Bool, map[string]bool{})
assert.AssertNotKindOf(t, reflect.Map, false)

AssertNotNil

func AssertNotNil(t testRunner, object any, msg ...any)

AssertNotNil asserts that an object is not nil.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertNotNil(t, true)
assert.AssertNotNil(t, "Hello, World!")
assert.AssertNotNil(t, 0)

AssertNotNumeric

func AssertNotNumeric(t testRunner, object any, msg ...any)

AssertNotNumeric checks if the object is not a numeric type. Numeric types are: Int, Int8, Int16, Int32, Int64, Float32, Float64, Uint, Uint8, Uint16, Uint32, Uint64, Complex64 and Complex128.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertNotNumeric(t, true)
assert.AssertNotNumeric(t, "123")

AssertNotPanics

func AssertNotPanics(t testRunner, f func(), msg ...any)

AssertNotPanics asserts that a function does not panic.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertNotPanics(t, func() {
	// some code that does not call a panic...
}) // => PASS

AssertNotRegexp

func AssertNotRegexp(t testRunner, regex any, txt any, msg ...any)

AssertNotRegexp asserts that a string does not match a given regexp.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertNotRegexp(t, "ab.*", "Hello, World!")

AssertNotSameElements

func AssertNotSameElements(t testRunner, expected any, actual any, msg ...any)

AssertNotSameElements asserts that two slices contains same elements (including pointers). The order is irrelevant.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

 assert.AssertNotSameElements(t, []string{"Hello", "World"}, []string{"Hello", "World", "World"})
 assert.AssertNotSameElements(t, []int{1,2}, []int{1,2,3})

 type A struct {
	  a string
 }
 assert.AssertNotSameElements(t, []*A{{a: "A"}, {a: "B"}, {a: "C"}}, []*A{{a: "A"}, {a: "B"}, {a: "C"}, {a: "D"}})

AssertNotUnique

func AssertNotUnique[elementType comparable](t testRunner, list []elementType, msg ...any)

AssertNotUnique asserts that the elements in a list are not unique.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertNotUnique(t, []int{1, 2, 3, 3})

AssertNotZero

func AssertNotZero(t testRunner, value any, msg ...any)

AssertNotZero asserts that the value is not the zero value for it's type.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertNotZero(t, 1337)
assert.AssertNotZero(t, true)
assert.AssertNotZero(t, "Hello, World")

AssertNumeric

func AssertNumeric(t testRunner, object any, msg ...any)

AssertNumeric asserts that the object is a numeric type. Numeric types are: Int, Int8, Int16, Int32, Int64, Float32, Float64, Uint, Uint8, Uint16, Uint32, Uint64, Complex64 and Complex128.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertNumeric(t, 123)
assert.AssertNumeric(t, 1.23)
assert.AssertNumeric(t, uint(123))

AssertPanics

func AssertPanics(t testRunner, f func(), msg ...any)

AssertPanics asserts that a function panics.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertPanics(t, func() {
	// ...
	panic("some panic")
}) // => PASS

AssertRegexp

func AssertRegexp(t testRunner, regex any, txt any, msg ...any)

AssertRegexp asserts that a string matches a given regexp.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertRegexp(t, "^a.*c$", "abc")

AssertSameElements

func AssertSameElements(t testRunner, expected any, actual any, msg ...any)

AssertSameElements asserts that two slices contains same elements (including pointers). The order is irrelevant.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

 assert.AssertSameElements(t, []string{"Hello", "World"}, []string{"Hello", "World"})
 assert.AssertSameElements(t, []int{1,2,3}, []int{1,2,3})
 assert.AssertSameElements(t, []int{1,2}, []int{2,1})

 type A struct {
	  a string
 }
 assert.AssertSameElements(t, []*A{{a: "A"}, {a: "B"}, {a: "C"}}, []*A{{a: "A"}, {a: "B"}, {a: "C"}})

AssertSubset

func AssertSubset(t testRunner, list any, subset any, msg ...any)

AssertSubset asserts that the second parameter is a subset of the list. The order is irrelevant.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertSubset(t, []int{1, 2, 3}, []int{1, 2})
assert.AssertSubset(t, []string{"Hello", "World", "Test"}, []string{"Test", "World"})

AssertTestFails

func AssertTestFails(t testRunner, test func(t TestingPackageWithFailFunctions), msg ...any)

AssertTestFails asserts that a unit test fails. A unit test fails if one of the following methods is called in the test function: Error, Errorf, Fail, FailNow, Fatal, Fatalf

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertTestFails(t, func(t assert.TestingPackageWithFailFunctions) {
	assert.AssertTrue(t, false)
}) // => Pass

assert.AssertTestFails(t, func(t assert.TestingPackageWithFailFunctions) {
	// ...
	t.Fail() // Or any other failing method.
}) // => Pass

AssertTrue

func AssertTrue(t testRunner, value any, msg ...any)

AssertTrue asserts that an expression or object resolves to true.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertTrue(t, true)
assert.AssertTrue(t, 1 == 1)
assert.AssertTrue(t, 2 != 3)
assert.AssertTrue(t, 1 > 0 && 4 < 5)

AssertUnique

func AssertUnique[elementType comparable](t testRunner, list []elementType, msg ...any)

AssertUnique asserts that the list contains only unique elements. The order is irrelevant.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertUnique(t, []int{1, 2, 3})
assert.AssertUnique(t, []string{"Hello", "World", "!"})

AssertZero

func AssertZero(t testRunner, value any, msg ...any)

AssertZero asserts that the value is the zero value for it's type.

When using a custom message, the same formatting as with fmt.Sprintf() is used.

Example:

assert.AssertZero(t, 0)
assert.AssertZero(t, false)
assert.AssertZero(t, "")

Capture

CaptureStderr

func CaptureStderr(capture func(w io.Writer) error) (string, error)

CaptureStderr captures everything written to stderr from a specific function. You can use this method in tests, to validate that your functions writes a string to the terminal.

Example:

stderr, err := assert.CaptureStderr(func(w io.Writer) error {
	_, err := fmt.Fprint(os.Stderr, "Hello, World!")
	assert.AssertNoError(t, err)
	return nil
})

assert.AssertNoError(t, err)
assert.AssertEqual(t, "Hello, World!", stderr)

CaptureStdout

func CaptureStdout(capture func(w io.Writer) error) (string, error)

CaptureStdout captures everything written to stdout from a specific function. You can use this method in tests, to validate that your functions writes a string to the terminal.

Example:

stdout, err := assert.CaptureStdout(func(w io.Writer) error {
	fmt.Println("Hello, World!")
	return nil
})

assert.AssertNoError(t, err)
assert.AssertEqual(t, "Hello, World!", stdout)

CaptureStdoutAndStderr

func CaptureStdoutAndStderr(capture func(stdoutWriter, stderrWriter io.Writer) error) (stdout, stderr string, err error)

CaptureStdoutAndStderr captures everything written to stdout and stderr from a specific function. You can use this method in tests, to validate that your functions writes a string to the terminal.

Example:

stdout, stderr, err := assert.CaptureStdoutAndStderr(func(stdoutWriter, stderrWriter io.Writer) error {
	fmt.Fprint(os.Stdout, "Hello")
	fmt.Fprint(os.Stderr, "World")
	return nil
})

assert.AssertNoError(t, err)
assert.AssertEqual(t, "Hello", stdout)
assert.AssertEqual(t, "World", stderr)

Fuzz Booleans

FuzzBoolFull

func FuzzBoolFull() []bool

FuzzBoolFull returns true and false in a boolean slice.

Fuzz Float64s

FuzzFloat64Full

func FuzzFloat64Full() (floats []float64)

FuzzFloat64Full returns a combination of every float64 testset and some random float64s (positive and negative).

FuzzFloat64GenerateRandomNegative

func FuzzFloat64GenerateRandomNegative(count int, min float64) (floats []float64)

FuzzFloat64GenerateRandomNegative generates random negative integers with a minimum of min. If the minimum is positive, it will be converted to a negative number. If it is set to 0, there is no limit.

FuzzFloat64GenerateRandomPositive

func FuzzFloat64GenerateRandomPositive(count int, max float64) (floats []float64)

FuzzFloat64GenerateRandomPositive generates random positive integers with a maximum of max. If the maximum is 0, or below, the maximum will be set to math.MaxInt64.

FuzzFloat64GenerateRandomRange

func FuzzFloat64GenerateRandomRange(count int, min, max float64) (floats []float64)

FuzzFloat64GenerateRandomRange generates random positive integers with a maximum of max. If the maximum is 0, or below, the maximum will be set to math.MaxInt64.

Fuzz Integers

FuzzIntFull

func FuzzIntFull() (ints []int)

FuzzIntFull returns a combination of every integer testset and some random integers (positive and negative).

FuzzIntGenerateRandomNegative

func FuzzIntGenerateRandomNegative(count, min int) (ints []int)

FuzzIntGenerateRandomNegative generates random negative integers with a minimum of min. If the minimum is 0, or above, the maximum will be set to math.MinInt64.

FuzzIntGenerateRandomPositive

func FuzzIntGenerateRandomPositive(count, max int) (ints []int)

FuzzIntGenerateRandomPositive generates random positive integers with a maximum of max. If the maximum is 0, or below, the maximum will be set to math.MaxInt64.

FuzzIntGenerateRandomRange

func FuzzIntGenerateRandomRange(count, min, max int) (ints []int)

FuzzIntGenerateRandomRange generates random integers with a range of min to max.

Fuzz Strings

FuzzStringEmailAddresses

func FuzzStringEmailAddresses() []string

FuzzStringEmailAddresses returns a test set with valid email addresses. The addresses may look like they are invalid, but they are all conform to RFC 2822 and could be used. You can use this test set to test your email validation process.

FuzzStringEmpty

func FuzzStringEmpty() []string

FuzzStringEmpty returns a test set with a single empty string.

FuzzStringFull

func FuzzStringFull() (ret []string)

FuzzStringFull contains all string test sets plus ten generated random strings. This test set is huge and should only be used if you want to make sure that no string, at all, can crash a process.

FuzzStringGenerateRandom

func FuzzStringGenerateRandom(count, length int) (result []string)

FuzzStringGenerateRandom returns random strings in a test set.

FuzzStringHtmlTags

func FuzzStringHtmlTags() []string

FuzzStringHtmlTags returns a test set with different html tags.

Example:

• link

FuzzStringLong

func FuzzStringLong() (testSet []string)

FuzzStringLong returns a test set with long random strings. Returns: [0]: Random string (length: 25) [1]: Random string (length: 50) [2]: Random string (length: 100) [3]: Random string (length: 1,000) [4]: Random string (length: 100,000)

FuzzStringNumeric

func FuzzStringNumeric() []string

FuzzStringNumeric returns a test set with strings that are numeric. The highest number in here is "9223372036854775807", which is equal to the maxmim int64.

FuzzStringUsernames

func FuzzStringUsernames() []string

FuzzStringUsernames returns a test set with usernames.

Fuzz Utils

FuzzUtilDistinctSet

func FuzzUtilDistinctSet[setType comparable](testSet []setType) []setType

FuzzUtilDistinctSet returns a set with removed duplicates.

Example:

uniqueSet := assert.FuzzUtilDistinctSet([]string{"A", "C", "A", "B", "A", "B", "C"})
// uniqueSet => []string{"A", "C", "B"}

FuzzUtilLimitSet

func FuzzUtilLimitSet[setType any](testSet []setType, max int) []setType

FuzzUtilLimitSet returns a random sample of a test set with a maximal size.

Example:

limitedSet := assert.FuzzUtilLimitSet(assert.FuzzStringFull(), 10)

FuzzUtilMergeSets

func FuzzUtilMergeSets[setType any](sets ...[]setType) (merged []setType)

FuzzUtilMergeSets merges multiple test sets into one. All test sets must have the same type.

Example:

mergedSet := assert.FuzzUtilMergeSets(assert.FuzzIntGenerateRandomNegative(3, 0), assert.FuzzIntGenerateRandomPositive(2, 0))

FuzzUtilModifySet

func FuzzUtilModifySet[setType any](inputSet []setType, modifier func(index int, value setType) setType) (floats []setType)

FuzzUtilModifySet returns a modified version of a test set.

Example:

 modifiedSet := assert.FuzzUtilModifySet(assert.FuzzIntFull(), func(i int, value int) int {
		return i * 2 // double every value in the test set
	})

FuzzUtilRunTests

func FuzzUtilRunTests[setType any](t testRunner, testSet []setType, testFunc func(t *testing.T, index int, f setType))

FuzzUtilRunTests runs a test for every value in a test set. You can use the value as input parameter for your functions, to sanity test against many different cases. This ensures that your functions have a correct error handling and enables you to test against hundreds of cases easily.

Example:

assert.FuzzUtilRunTests(t, assert.FuzzStringEmailAddresses(), func(t *testing.T, index int, emailAddress string) {
	// Test logic
	// err := YourFunction(emailAddress)
	// assert.AssertNoError(t, err)
	// ...
})

GetColorsEnabled

func GetColorsEnabled() bool

GetColorsEnabled returns current value of ColorsEnabled setting. ColorsEnabled controls if assert should print colored output.

GetDiffContextLines

func GetDiffContextLines() int

GetDiffContextLines returns current value of DiffContextLines setting. DiffContextLines setting controls how many lines are shown around a changed diff line. If set to -1 it will show full diff.

GetLineNumbersEnabled

func GetLineNumbersEnabled() bool

GetLineNumbersEnabled returns current value of LineNumbersEnabled setting. LineNumbersEnabled controls if line numbers should be printed in failing tests.

GetRandomSeed

func GetRandomSeed() int64

GetRandomSeed returns current value of the random seed setting.

GetShowStartupMessage

func GetShowStartupMessage() bool

GetShowStartupMessage returns current value of showStartupMessage setting. showStartupMessage setting controls if the startup message should be printed.

Settings

SetColorsEnabled

func SetColorsEnabled(enabled bool)

SetColorsEnabled controls if assert should print colored output. You should use this in the init() method of the package, which contains your tests.

This setting can also be set by the command line flag --assert.disable-color.

Example:

init() {
  assert.SetColorsEnabled(false) // Disable colored output
  assert.SetColorsEnabled(true)  // Enable colored output
}

SetDiffContextLines

func SetDiffContextLines(lines int)

SetDiffContextLines controls how many lines are shown around a changed diff line. If set to -1 it will show full diff. You should use this in the init() method of the package, which contains your tests.

This setting can also be set by the command line flag --assert.diff-context-lines.

Example:

init() {
  assert.SetDiffContextLines(-1) // Show all diff lines
  assert.SetDiffContextLines(3)  // Show 3 lines around every changed line
}

SetLineNumbersEnabled

func SetLineNumbersEnabled(enabled bool)

SetLineNumbersEnabled controls if line numbers should be printed in failing tests. You should use this in the init() method of the package, which contains your tests.

This setting can also be set by the command line flag --assert.disable-line-numbers.

Example:

init() {
  assert.SetLineNumbersEnabled(false) // Disable line numbers
  assert.SetLineNumbersEnabled(true)  // Enable line numbers
}

SetRandomSeed

func SetRandomSeed(seed int64)

SetRandomSeed sets the seed for the random generator used in assert. Using the same seed will result in the same random sequences each time and guarantee a reproducible test run. Use this setting, if you want a 100% deterministic test. You should use this in the init() method of the package, which contains your tests.

This setting can also be set by the command line flag --assert.seed.

Example:

init() {
  assert.SetRandomSeed(1337) // Set the seed to 1337
  assert.SetRandomSeed(time.Now().UnixNano()) // Set the seed back to the current time (default | non-deterministic)
}

SetShowStartupMessage

func SetShowStartupMessage(show bool)

SetShowStartupMessage controls if the startup message should be printed. You should use this in the init() method of the package, which contains your tests.

This setting can also be set by the command line flag --assert.disable-startup-message.

Example:

init() {
  assert.SetShowStartupMessage(false) // Disable the startup message
  assert.SetShowStartupMessage(true)  // Enable the startup message
}

Snapshot

SnapshotCreate

func SnapshotCreate(name string, snapshotObject any) error

SnapshotCreate creates a snapshot of an object, which can be validated in future test runs. Using this function directly will override previous snapshots with the same name. You most likely want to use SnapshotCreateOrValidate.

NOTICE: \r\n will be replaced with \n to make the files consistent between operating systems.

Example:

assert.SnapshotCreate(t.Name(), objectToBeSnapshotted)

SnapshotCreateOrValidate

func SnapshotCreateOrValidate(t testRunner, name string, object any, msg ...any) error

SnapshotCreateOrValidate creates a snapshot of an object which can be used in future test runs. It is good practice to name your snapshots the same as the test they are created in. You can do that automatically by using t.Name() as the second parameter, if you are using the inbuilt test system of Go. If a snapshot already exists, the function will not create a new one, but validate the exisiting one. To re-create a snapshot, you can delete the according file in /testdata/snapshots/.

NOTICE: \r\n will be replaced with \n to make the files consistent between operating systems.

Example:

assert.SnapshotCreateOrValidate(t, t.Name(), object)
assert.SnapshotCreateOrValidate(t, t.Name(), object, "Optional Message")

SnapshotValidate

func SnapshotValidate(t testRunner, name string, actual any, msg ...any) error

SnapshotValidate validates an already exisiting snapshot of an object. You most likely want to use SnapshotCreateOrValidate.

NOTICE: \r\n will be replaced with \n to make the files consistent between operating systems.

Example:

assert.SnapshotValidate(t, t.Name(), objectToBeValidated)
assert.SnapshotValidate(t, t.Name(), objectToBeValidated, "Optional message")

---

Made with ❤️ by @MarvinJWendt and contributors! | MarvinJWendt.com