Testing with Go

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An integral part of the development licefycle is writing tests. Write tests early, write tests often as they say. Go makes it very easy to write tests. The following post will go through the basics of testing with Go. Let’s say we have a program that counts the number of vowels, consonants, digits and everything else within an input string. It may look something like this: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 package main import ( "flag" "fmt" ) // CountChars counts the number of characters in a string func CountChars(str string) (int, int, int, int) { vcount := 0 ccount := 0 dcount := 0 ocount := 0 for i := 0; i < len(str); i++ { switch str[i] { case 'a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U': vcount++ case 'b', 'c', 'd', 'f', 'g', 'h', 'j', 'k', 'l', 'm', 'n', 'p', 'q', 'r', 's', 't', 'v', 'w', 'x', 'y', 'z', 'B', 'C', 'D', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'V', 'W', 'X', 'Y', 'Z': ccount++ case '1', '2', '3', '4', '5', '6', '7', '8', '9', '0': dcount++ default: ocount++ } } return vcount, ccount, dcount, ocount } func main() { inputStr := flag.String("inputStr", "", "The input string") flag.Parse() vowels, consonants, digits, other := CountChars(*inputStr) fmt.Println("Number of vowel chars: ", vowels) fmt.Println("Number of consonant chars: ", consonants) fmt.Println("Number of digit chars: ", digits) fmt.Println("Number of other chars: ", other) } Go provides a testing package to help with writing unit tests. Unit tests are contained in files typically ending in *_test.go. So to test the main function, you would have main_test.go in the same directory and so on. Files whose names begin with _ or . are ignored. There are three types of functions that are typically contained in a test file: TestXxx, ExampleXxx, BenchmarkXxx