Assertion for Golang

A collection of Golang assertion functions for verifying invariants.

• Installation
• Getting Started
• Available Assertions
  • Equality
  • Comparison
  • Value
  • String
  • Slice or Array
  • Map
  • Error Handling
• Custom Error Message
• License

Installation

To install this library, just use go get command like the following line:

go get -u github.com/ghosind/go-assert

Getting Started

This library provided assertion functions to verify the equality of values, or assert for nil:

func TestExample(t *testing.T) {
  // var actual
  // var expect

  // assert equality
  assert.Equal(t, actual, expect)

  // assert inequality
  assert.NotEqual(t, actual, expect)

  // you can also use DeepEqual to assert the equality that also checks the type between the values
  assert.DeepEqual(t, actual, expect)

  // var object

  // assert for nil
  assert.Nil(t, object)

  // assert for not nil
  assert.NotNil(t, object)
}

You can use True method to check whether a value is truthy or falsy (is the zero value of the type or not).

func TestExample(t *testing.T) {
  assert.True(t, 1) // success
  assert.True(t, 0) // fail
  assert.True(t, "test") // success
  assert.True(t, "") // fail
}

If you want to test the value of a string, you can use Match method to test it with a regular expression pattern.

func TestExample(t *testing.T) {
  pattern := regexp.MustCompile(`^https?:\/\/`)
  assert.Match(t, "https://example.com", pattern) // success
  assert.Match(t, "example.com", pattern) // fail

  // you can also use `MatchString` to test it without compiling the regexp pattern
  assert.MatchString(t, "https://example.com", `^https?:\/\/`) // success
}

Since v0.2.0, we also provided some assertions for array/slice, for example, you can use ContainsElement to check whether an array or a slice contains a specified element.

func TestExample(t *testing.T) {
  arr := []int{1, 2, 3}
  assert.ContainsElement(arr, 1) // success
  assert.ContainsElement(arr, 4) // fail
}

It also provided assertion functions to verify a function will panic or not:

func TestPanic(t *testing.T) {
  // assert panic
  assert.Panic(t, func () {
    // do something

    panic()
  })

  // assert no panic
  assert.NotPanic(t, func () {
    // do something

    // panic()
  })
}

For every assertion functions, it also provided XXXNow functions to stop the execution if the test is failed.

func TestExample(t *testing.T) {
  // var actual
  // var expect

  // The following line will set the test result to fail and stop the execution
  assert.EqualNow(t, actual, expect)

  // The following lines will never execute if they are not equal.
  // ...
}

Every assertion will not terminate the testing workflow. However, they'll return an error if the verification failed, and you can check the return value to get the verification result.

func TestExample(t *testing.T) {
  if err := assert.Equal(t, actual, expect); err != nil {
    // terminate test
    t.Fail()
  }
}

If you need to assert many times, you can also create an Assertion instance:

func TestExample(t *testing.T) {
  assertion := assert.New(t)

  // test equality
  assertion.Equal(actual, expect)

  // Test inequality
  assertion.NotEqual(actual, expect)
}

Available Assertions

Equality

• DeepEqual and NotDeepEqual: assert the deep equality or inequality.

  Since v0.1.0

• Equal and NotEqual: assert the equality or inequality.

  Since v0.1.5

Comparison

• Gt: assert the first value is greater than the second value.

  Since v1.0.0

• Gte: assert the first value is greater than or equal to the second value.

  Since v1.0.0

• Lt: assert the first value is less than the second value.

  Since v1.0.0

• Lte: assert the first value is less than or equal to the second value.

  Since v1.0.0

Value

• Nil and NotNil: assert the value is nil or not.

  Since v0.1.1

• True and NotTrue: assert the truthy of the value.

  Since v0.1.4

String

• ContainsString and NotContainsString: assert whether the string contains the substring or not.

  Since v0.1.7

• HasPrefixString and NotHasPrefixString: assert whether the string have the prefix string or not.

  Since v0.1.7

• HasSuffixString and NotHasSuffixString: assert whether the string have the suffix string or not.

  Since v0.1.7

• Match and NotMatch: assert whether the string matches the regular expression pattern or not.

  Since v0.1.5

• MatchString and NotMatchString: compile the regular expression pattern and assert whether the string matches the pattern or not.

  Since v0.1.5

Slice or Array

• ContainsElement and NotContainsElement: assert whether the array or slice contains the specified element or not.

  Since v0.2.0

Map

• MapHasKey and NotMapHasKey: assert whether the map contains the specified key or not.

  Since v0.2.1

• MapHasValue and NotMapHasValue: assert whether the map contains the specified value or not.

  Since v0.2.1

Error Handling

• Panic and NotPanic: assert the function will panic or not.

  Since v0.1.0

• PanicOf: assert the function will panic by the expected error.

  Since v0.1.0

• NotPanicOf: assert the function will not panic, or it will panic but it is not by the unexpected error.

Since v0.1.0

Custom Error Message

You can customize the error message if you don't like the default message. Every assertion function accepts an optional message arguments list, and the first argument is the argument is the format string of the custom message.

actual := 1
expect := 2
assert.Equal(actual, expect)
// assert error: 1 != 2

assert.Equal(actual, expect, "unexpected result")
// unexpected result

assert.Equal(actual, expect, "actual = %v, expect = %v", actual, expect)
// actual = 1, expect = 2

For custom error messages, the first argument of messages must be the format string, it'll fall back to the default error message if not a string.

License

This project was published under the MIT license, you can see LICENSE file to get more information.