zehiraa/go-testing

Go Testing

Conventions

• All of our tests must have the format _test.go
• Test files should be in the same package as your code.
• In Go all tests go inside a file named similar to the file you are testing. So if you want to test code in main.go, then you write the tests in main_test.go
• In the test file we will always need to import the testing package. (Build-in package)
• There is the following signature for every test you write, func TestXxx(*testing.T), where the first X MUST be Uppercase.
• Calls t.Error or t.Fail to indicate a failure (I called t.Errorf to provide more details)
• t.Log can be used to provide non-failing debug information

Some useful commands

Test commands

- go test
- go test –v 
- go test –run  "TestName"

Coverage commands & Visualization

- go test –cover
- go test –cover –coverprofile=c.out
- tool cover –html=c.out –o coverage.html

Unit Testing

Basic Test

• Log or Logf : Write documentation out into the log output.
• Error or Errorf: Write documentation and also say that this test is failed but we are continue moving forward to execute code in this test.
• Fatal or Fatalf : Similarly, document that this test is failed but we are done. We move on to the next test function.

• "Given, When, Should" format

• Given: Why are we writing this test?
• When: What data are we using for this test?
• Should: When are we expected to see it happen or not happen?

Table Test

• Set up a data structure of input to expected output.
• This way we don't need a separate function for each one of these. We just have 1 test function.
• As we go along, we just add more to the table.

Sub Test

• Sub test helps us streamline our test functions, filters out command-line level big tests into smaller sub tests.

Assertion/Mocking

• stretchr/testify one of the most popular go testing library (link: https://github.com/stretchr/testify)
• to install :

    go get github.com/stretchr/testify

• easy assertion

  -> assert.Equal(t, Calculate(2), 4)
  -> assert.NotEqual(t, Calculate(2), 5)
  -> assert.Nil(status)
  -> assert.NotNil(object)

• mockery provides the ability to easily generate mocks for golang interfaces using the stretchr/testify/mock package. -> to install :

   go get github.com/vektra/mockery/.../

  -> to generate mock :

   mockery -name "<interfaceToMock>"

Ginkgo

• Ginkgo builds on Go's testing package, allowing expressive Behavior-Driven Development ("BDD") style tests.
• It is typically (and optionally) paired with the Gomega matcher library. -> to install ginkgo & gomega:

   go get github.com/onsi/ginkgo/ginkgo
   go get github.com/onsi/gomega/...

• General format:

        Describe("the strings package", func() {
        Context("strings.Contains()", func() {
            When("the string contains the substring in the middle", func() {
            It("returns `true`", func() {
                Expect(strings.Contains("Ginkgo is awesome", "is")).To(BeTrue())
            })
            })
        })
        })