make it work

Author: Oppodelldog

cmd/main.go

@@ -8,12 +8,19 @@ import (
 	"github.com/Oppodelldog/git-commit-hook"
 )
 
+type rewriteCommitMessageFuncDef func(string) error
+type exitFuncDef func(code int)
+
+var rewriteCommitMessageFunc = rewriteCommitMessageFuncDef(gitcommithook.RewriteCommitMessage)
+var exitFunc = exitFuncDef(os.Exit)
+
 func main() {
-	commitMessage, err := gitcommithook.ModifyGitCommitMessage(os.Args[1])
+	commitMessageFile := os.Args[1]
+	err := rewriteCommitMessageFunc(commitMessageFile)
 	if err != nil {
-		fmt.Printf("error in git hook: %s", err.Error())
-		os.Exit(1)
+		fmt.Print(err)
+		exitFunc(1)
+		return
 	}
-
-	fmt.Print(commitMessage)
+	exitFunc(0)
 }

cmd/main_test.go

@@ -0,0 +1,162 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"testing"
+
+	"reflect"
+
+	"github.com/stretchr/testify/assert"
+)
+
+const testPath = "/tmp/git-commit-hook"
+const featureBranch = "feature/PROJECT-123"
+const nonFeatureBranch = "release/v0.1.2"
+const commitMessageFile = ".git/COMMIT_EDITMSG"
+
+//originals contains original values might be overwritten in tests
+var originals = struct {
+	osArgs                   []string
+	rewriteCommitMessageFunc rewriteCommitMessageFuncDef
+	exitFunc                 exitFuncDef
+	osStdout                 *os.File
+}{
+	osArgs: os.Args,
+	rewriteCommitMessageFunc: rewriteCommitMessageFunc,
+	exitFunc:                 exitFunc,
+	osStdout:                 os.Stdout,
+}
+
+//restoreOriginals restores original values
+func restoreOriginals() {
+	os.Args = originals.osArgs
+	rewriteCommitMessageFunc = originals.rewriteCommitMessageFunc
+	exitFunc = originals.exitFunc
+	os.Stdout = originals.osStdout
+	os.RemoveAll(testPath)
+}
+
+func TestMain_HappyPath(t *testing.T) {
+	defer restoreOriginals()
+
+	initGitRepositoryWithBranch(t, featureBranch)
+	setCommitMessage(t, "initial commit")
+	prepareGitHookCall()
+
+	programExistsWith(t, 0)
+
+	main()
+
+	expectedCommitMessage := fmt.Sprintf("%s: initial commit", featureBranch)
+	modifiedCommitMessage := readCommitMessage(t)
+	assert.Exactly(t, expectedCommitMessage, modifiedCommitMessage)
+}
+
+func readCommitMessage(t *testing.T) string {
+	b, err := ioutil.ReadFile(commitMessageFile)
+	if err != nil {
+		t.Fatalf("Did not exepect ioutil.ReadFile to return an error, but got: %v", err)
+	}
+
+	return string(b)
+}
+
+func prepareGitHookCall() {
+	os.Args = []string{"git", commitMessageFile}
+}
+
+func setCommitMessage(t *testing.T, commitMessage string) {
+	err := ioutil.WriteFile(commitMessageFile, []byte(commitMessage), 0777)
+	if err != nil {
+		t.Fatalf("Did not exepect ioutil.WriteFile to return an error, but got: %v", err)
+	}
+}
+
+func TestMain_ErrorCase_CommitMessageFileNotFound(t *testing.T) {
+	defer restoreOriginals()
+
+	os.Args = []string{"git", commitMessageFile}
+	w, stdOutChannel := captureStdOut(t)
+
+	programExistsWith(t, 1)
+
+	main()
+
+	w.Close()
+
+	stdOutput := <-stdOutChannel
+	assert.Exactly(t, "error reading commit message from '.git/COMMIT_EDITMSG': open .git/COMMIT_EDITMSG: no such file or directory", stdOutput)
+}
+
+func TestMain_ErrorCase_GitError(t *testing.T) {
+	defer restoreOriginals()
+
+	initGitRepositoryWithBranch(t, nonFeatureBranch)
+	setCommitMessage(t, "@noissue rc-fix")
+	os.Args = []string{"git", commitMessageFile}
+	w, stdOutChannel := captureStdOut(t)
+
+	programExistsWith(t, 1)
+
+	main()
+
+	w.Close()
+
+	stdOutput := <-stdOutChannel
+	assert.Exactly(t, "error modifying commit message: feature reference is required in '@noissue rc-fix'", stdOutput)
+}
+
+func TestMain_ExitFuncUsesAppropriateOsFunc(t *testing.T) {
+	assert.Exactly(t, reflect.ValueOf(os.Exit).Pointer(), reflect.ValueOf(exitFunc).Pointer())
+}
+
+func programExistsWith(t *testing.T, expectedExitCode int) {
+	exitFunc = func(exitCode int) {
+		assert.Exactly(t, expectedExitCode, exitCode)
+	}
+}
+
+func captureStdOut(t *testing.T) (*os.File, chan string) {
+	r, w, err := os.Pipe()
+	if err != nil {
+		t.Fatalf("Did not exepect os.Pipe to return an error, but got: %v", err)
+	}
+	os.Stdout = w
+	stdOutChannel := make(chan string)
+	go func() {
+		defer r.Close()
+
+		scanner := bufio.NewScanner(r)
+		if scanner.Scan() {
+			stdOutChannel <- scanner.Text()
+		}
+
+		close(stdOutChannel)
+	}()
+	return w, stdOutChannel
+}
+
+func initGitRepositoryWithBranch(t *testing.T, branchName string) {
+	os.RemoveAll(testPath)
+	os.MkdirAll(testPath, 0777)
+	os.Chdir(testPath)
+	git(t, "init")
+	err := ioutil.WriteFile("README.md", []byte("# test file"), 0777)
+	if err != nil {
+		t.Fatalf("could not write README.md: %v", err)
+	}
+	git(t, "add", "-A")
+	git(t, "commit", "-m", "initial commit")
+	git(t, "checkout", "-b", branchName)
+}
+
+func git(t *testing.T, args ...string) {
+	o, err := exec.Command("git", args...).CombinedOutput()
+	if err != nil {
+		t.Fatalf("'git %v init' failed with error: %v - output: %s", args, err, string(o))
+	}
+}