Add dry run mode, Fixes #9 (#71)

Author: rdsubhas

cmd/root.go

@@ -14,6 +14,7 @@ import (
 type mykeOpts struct {
 	Verbose  []bool `short:"v" long:"verbose" description:"show verbose logs"`
 	File     string `short:"f" long:"file" description:"yml file to load" default:"myke.yml"`
+	DryRun   bool   `short:"n" long:"dry-run" description:"print tasks without running them"`
 	Version  bool   `long:"version" description:"print myke version"`
 	Template string `long:"template" description:"template file to render"`
 	License  bool   `long:"license" description:"show open source licenses"`

cmd/run.go

@@ -14,7 +14,7 @@ func Run(opts *mykeOpts, tasks []string) error {
 
 	w := loadWorkspace(opts.File)
 	for _, q := range queries {
-		err := core.ExecuteQuery(&w, q)
+		err := core.ExecuteQuery(&w, q, opts.DryRun)
 		if err != nil {
 			return errors.Wrap(err, "error running command")
 		}

core/execution.go

@@ -16,10 +16,11 @@ type Execution struct {
 	Query     *Query
 	Project   *Project
 	Task      *Task
+	DryRun    bool
 }
 
 // ExecuteQuery executes the given query in the workspace
-func ExecuteQuery(w *Workspace, q Query) error {
+func ExecuteQuery(w *Workspace, q Query, dryRun bool) error {
 	matches := q.search(w)
 	if len(matches) == 0 {
 		return errors.New("no task matched: " + q.Raw)
@@ -30,6 +31,7 @@ func ExecuteQuery(w *Workspace, q Query) error {
 			Query:     &q,
 			Project:   &match.Project,
 			Task:      &match.Task,
+			DryRun:    dryRun,
 		}
 		err := e.Execute()
 		if err != nil {
@@ -43,6 +45,10 @@ func ExecuteQuery(w *Workspace, q Query) error {
 func (e *Execution) Execute() error {
 	start := time.Now()
 	displayName := e.Project.Name + "/" + e.Task.Name
+	if e.DryRun {
+		log.Infof("%v: Will run", displayName)
+		return nil
+	}
 	log.Infof("%v: Running", displayName)
 
 	err := retry(func(attempt int) (bool, error) {

examples/tag/package_test.go

@@ -6,6 +6,9 @@ import (
 )
 
 var tests = []TestTable{
+	{`tag`, `tag`, `tags1/tag`},
+	{`tag`, `tag`, `tags2/tag`},
+	{`tag`, `--dry-run tag`, `(?s)tags1/tag: Will run.*tags2/tag: Will run`},
 	{`tagA/tag`, `tagA/tag`, `tags1 tag`},
 	{`tagA/tag`, `tagA/tag`, `(tags2){0}`},
 	{`tagB/tag`, `tagB/tag`, `tags1/tag`},