README.md

Step 1. What you need to know about testing and writing tests in Go.

Testing is necessary for weaklings who can not write working code at the first attempt. Therefore, there are many tools for writing tests in the world. Go is not an exception. Go has a testing package, whose functionality is enough for everyone.

The test files in GO are usually in the same folder as regular files. They can be recognized by the presence of _test.go in the file name. The compiler will understand that the _test.go files do not need to be included in the build, but when you run the go test tool, these files will be used just like that

For example, let's see how the math Go package is tested.

package math

import "testing"

func TestAverage(t *testing.T) {
  var v float64
  v = Average([]float64{1,2})
  if v != 1.5 {
    t.Error("Expected 1.5, got ", v)
  }
}

Launching the tests are going to the command Gogo test

$ cd /usr/local/go/src/math
$ go test
PASS
ok      math    0.010s

If you want. The Go community also promotes to use the so-called table tests instead of copy-paste in the tests. In this case, we have pairs of initial value and result. And we run the tests in a loop

package math

import "testing"

type testpair struct {
  values []float64
  average float64
}

var tests = []testpair{
  { []float64{1,2}, 1.5 },
  { []float64{1,1,1,1,1,1}, 1 },
  { []float64{-1,1}, 0 },
}

func TestAverage(t *testing.T) {
  for _, pair := range tests {
    v := Average(pair.values)
    if v != pair.average {
      t.Error(
        "For", pair.values,
        "expected", pair.average,
        "got", v,
      )
    }
  }

Documentation for the testing package

And if you tired of writing constantly

if smth != anoher {
   t.Error("Error")
}

That is, the testify/assert package

Congratulations!

You now know how to test in Go and by which tools. We will write tests in our project. There is no sense without them. Continuation in the next part