Refactor versioner (Azure#1461)

* Ensures go.mod exists before doing actual work

* Fix wrong module name

* Add a new test scenario

* Some refinement on testcases for versioner

* Update version in version.go

* Only keep one line of tag in version.go

* Minor fix

* No need to print tag to stdout

* New test scenario

* Fix linter problem

* Return error from filepath.Abs

* Add test for update version.go file

* Remove method that ensures existence of go.mod file, and some redaudent
test cases

* Formatting code after versioning done

* Refine tests

* Fix a bug that when update applied to v2, the go.mod file does not
update as v2

* Clean up

* Purely file rename, nothing else changed

* Add functionality for run tool in root folder

* Add root command again

* Fix format

* Typo fix

* Add test for list all stage folders

* Add two functions for programmatically call

* Fix CI failure

* Add a new test case for more realistic

* Fix errors in the new test case

* Fix gofmt issues

* Add a new struct to cover this scenario

* Add test for go vet

* Add new test case for one line import

* Format stage folder first to avoid un-expected changes in code

* Fix a bug in regex used for multiline import statement

* Move getPkgs method to an internal package and exported

* Fix broken tests

* Add comment to silence golint error

* Init command

* Format change

* More minor tweak to satisfy golint

tools/internal/pkgs/pkgs.go

@@ -46,20 +46,12 @@ func (p Pkg) GetAPIVersion() (string, error) {
 	if p.IsARMPkg() {
 		// management-plane
 		regex := regexp.MustCompile(`mgmt/(.+)/`)
-		groups := regex.FindStringSubmatch(dest)
-		if len(groups) < 2 {
-			return "", fmt.Errorf("cannot find api version in %s", dest)
-		}
-		versionString := groups[1]
+		versionString := regex.FindStringSubmatch(dest)[1]
 		return versionString, nil
 	}
 	// data-plane
 	regex := regexp.MustCompile(`/(\d{4}-\d{2}.*|v?\d+(\.\d+)?)/`)
-	groups := regex.FindStringSubmatch(dest)
-	if len(groups) < 2 {
-		return "", fmt.Errorf("cannot find api version in %s", dest)
-	}
-	versionString := groups[1]
+	versionString := regex.FindStringSubmatch(dest)[1]
 	if versionString == "" {
 		return "", fmt.Errorf("does not find api version in data plane package %s", dest)
 	}

tools/versioner/cmd/init.go

@@ -126,9 +126,6 @@ func theInitCommand(args []string) error {
 		if err := createGoModFile(root, p); err != nil {
 			errs = append(errs, err)
 		}
-		if err := createChangeLogFile(root, p); err != nil {
-			errs = append(errs, err)
-		}
 	}
 	// handle errors
 	if len(errs) == 0 {
@@ -147,8 +144,7 @@ func createVersionFile(root string, p pkgs.Pkg, tagPrefix string) error {
 		return fmt.Errorf("failed to get api version of package %s: %+v", p.Dest, err)
 	}
 	tag := tagPrefix + "/" + startingModVer
-	ver := versionGoRegex.FindString(startingModVer)
-	content := fmt.Sprintf(initialVerGo, p.Package.Name, ver, p.Package.Name, apiVersion, ver, tag)
+	content := fmt.Sprintf(initialVerGo, p.Package.Name, startingModVer, p.Package.Name, apiVersion, startingModVer, tag)
 	err = ioutil.WriteFile(verFilePath, []byte(content), 0755)
 	if err != nil {
 		return fmt.Errorf("failed to write file %s: %+v", verFilePath, err)
@@ -172,17 +168,6 @@ func createGoModFile(root string, p pkgs.Pkg) error {
 	return nil
 }
 
-func createChangeLogFile(root string, p pkgs.Pkg) error {
-	logFilePath := filepath.Join(root, p.Dest, changeLogName)
-	log, err := os.Create(logFilePath)
-	if err != nil {
-		return fmt.Errorf("failed to create %s: %v", changeLogName, err)
-	}
-	defer log.Close()
-	_, err = log.WriteString("No changes to exported content compared to the previous release.\n")
-	return err
-}
-
 func loadExceptions(exceptFile string) (map[string]bool, error) {
 	result := make(map[string]bool)
 	if exceptFile == "" {

tools/versioner/cmd/unstage.go

@@ -58,8 +58,6 @@ var (
 	getTagsHook TagsHookFunc
 )
 
-const changeLogName = "CHANGELOG.md"
-
 // TagsHookFunc is a func used for get tags from remote
 type TagsHookFunc func(string, string) ([]string, error)
 
@@ -402,6 +400,7 @@ func writeChangelog(stage string, mod modinfo.Provider) error {
 	if mod.NewModule() {
 		return nil
 	}
+	const changeLogName = "CHANGELOG.md"
 	rpt := mod.GenerateReport()
 	log, err := os.Create(filepath.Join(stage, changeLogName))
 	if err != nil {