Automated Testing

contents you will get from this article

1. What is Automated Testing
2. How to use Automated Testing
3. What is Table-driven tests and how to use it to make you testing program effively

What is Automated testing?

• An automated test is a seperate program that executes components of your main program,and verifies they behave as expected.

Example:suppose we have a function named JoinWithCommas(),which take a slice of strings and return a combined string.
When we send []string{"apple","orange"}to it,we hope we can get "apple and orange",however when we send []string{"apple","orange","banana"} to it,we hope we can get "apple,orange and banana"

JoinWithCommas({"apple","orange"})=="apple and orange"
JoinWithCommas({"apple","orange","banana"})=="apple,orange and banana"

As you can see ,before write and run the program,we have predict the returned values of the program.

Let's begin to learn automated testing in the way of fixing our JoinWithComms function:

func JoinWithCommas(phrases []string) string {
	result := strings.Join(phrases[:len(phrases)-1], ",")
    result += ", and "
	result += phrases[len(phrases)-1]
	return result
}

Look at the first version of our JoinWithCommas function,when we run it in the main func:

func main(){
    phrases:=[]string{"my parents","a rodeo clown"}
    fmt.Println("A photo of",prose.JoinWithCommas(phrases))
    phrases:=[]string{"my parents","a rodeo clown","a prize bull"}
}

Look at the result above it have a mistake,as it mean that parents are a redeo clown and a prize bull,that must be an error.

Let's fix it now

func JoinWithCommas(phrases []string) string {
	result := strings.Join(phrases[:len(phrases)-1], ",")
	result += " ,and "
	result += phrases[len(phrases)-1]
	return result
}

We simply add and "," at the last string but that cause another error.

So how can we make sure that every time we fix our program it won't cause another error?

Let's look at the test

"join_test.go"

func TestTwoElements(t *testing.T)  {
	list := []string{"apple", "orange"}
	if JoinWithCommas(list) != "apple and orange" {
		t.Error("did't match expected value")
	}
}

• The join part of the filename is not important ,but the _test.go part is;the go test tool looks for files named with that suffix.
• Function name should begin with "Test"
• Function should be passed a pointer to a testing.T value.

Running tests with the "go test"command

We can run the tests in this way.