Merge pull request #3 from redbubble/skip-flag

Allow users to skip selected apps

Author: lucaswilric

README.md

@@ -44,6 +44,9 @@ starts the named application in Development mode, with its dependencies in Depen
 `--mode`, `-m`
 : Specify the mode. Default: `development`
 
+`--skip`, `-s`
+: Names of any apps you don't want to start. Can be specified multiple times.
+
 `--verbose`, `-v`
 : Print some more information about what's happening.
 

cmd/start.go

@@ -15,6 +15,7 @@ import (
 )
 
 var mode string
+var skip []string
 
 // startCmd represents the start command
 var startCmd = &cobra.Command{
@@ -40,9 +41,13 @@ var startCmd = &cobra.Command{
 		bail(err)
 
 		apps := make([]domain.App, 0, 1)
-		apps, err = resolver.Add(apps, app)
+		apps, err = resolver.Add(apps, app, skip)
 		bail(err)
 
+		if len(apps) == 0 {
+			bail(fmt.Errorf("There are no apps to start. Consider checking %s/devon.conf.yaml to figure out what's going on.", app.SourceDir))
+		}
+
 		if viper.IsSet("verbose") {
 			fmt.Println("Devon will start these apps:")
 
@@ -84,6 +89,7 @@ func init() {
 	rootCmd.AddCommand(startCmd)
 
 	startCmd.PersistentFlags().StringVarP(&mode, "mode", "m", "development", "The mode to run in, e.g. 'development' or 'dependency'. Default: development")
+	startCmd.PersistentFlags().StringSliceVarP(&skip, "skip", "s", []string{}, "Names of any apps you don't want to start. Can be specified multiple times.")
 }
 
 func getAppName(args []string) (string, error) {

example.yaml

@@ -36,7 +36,7 @@ modes:
     start-command: ["make", "local"]
     # This app takes the default list and extends it.
     dependencies:
-      <<: *default_dependencies
-      extra-app: dependency
-      # We can override existing settings, too:
-      my-app: development
+      - name: extra-app
+        mode: dependency
+      - name: my-app
+        mode: development

resolver/resolver.go

@@ -7,8 +7,8 @@ import (
 	"github.com/redbubble/devon/domain"
 )
 
-func Add(apps []domain.App, app domain.App) ([]domain.App, error) {
-	startingApps, err := add(apps, app, make([]string, 0, len(apps)))
+func Add(apps []domain.App, app domain.App, skip []string) ([]domain.App, error) {
+	startingApps, err := add(apps, app, skip, make([]string, 0, len(apps)))
 
 	if err != nil {
 		return nil, err
@@ -17,42 +17,36 @@ func Add(apps []domain.App, app domain.App) ([]domain.App, error) {
 	return startingApps, nil
 }
 
-func add(apps []domain.App, app domain.App, depChain []string) ([]domain.App, error) {
+func add(apps []domain.App, app domain.App, skip []string, depChain []string) ([]domain.App, error) {
 	var startingApps []domain.App
 
+	// Has the user said they want to skip this app?
+	// If so, let's return early.
+	if checkSkip(app.Name, skip) {
+		return apps, nil
+	}
+
 	// Does the dependency chain already include this app?
 	// If so, we've got a circular dependency, so return an error.
-	for _, depName := range depChain {
-		if depName == app.Name {
-			depChainStr := strings.Join(append(depChain, app.Name), "->")
-			err := fmt.Errorf("Circular dependency when resolving dependencies: %s", depChainStr)
-			return []domain.App{}, err
-		}
+	if checkCircularDependency(app.Name, depChain) {
+		depChainStr := strings.Join(append(depChain, app.Name), "->")
+		err := fmt.Errorf("Circular dependency when resolving dependencies: %s", depChainStr)
+
+		return []domain.App{}, err
 	}
 
-	// Does the list of apps already include this app?
-	// If so, we need to compare the modes.
-	//   If the modes are the same, then this dependency is already satisfied.
-	//    There's nothing to do, so we can return now.
-	//   If the modes are different, we have conflicting dependencies.
-	//    Return an error.
-	for j := 0; j < len(apps); j++ {
-		if apps[j].Name == app.Name {
-			if apps[j].Mode.Name == app.Mode.Name {
-				// The app we want, in the mode we want, is
-				// already in the list. Therefore, there's
-				// nothing to do.
-				return apps, nil
-			} else {
-				err := fmt.Errorf("Dependency conflict when resolving dependencies: %s in '%s' mode conflicts with %s in '%s' mode.",
-					app.Name,
-					app.Mode.Name,
-					apps[j].Name,
-					apps[j].Mode.Name)
-
-				return []domain.App{}, err
-			}
-		}
+	if conflict, conflictingApp := checkDependencyConflict(app, apps); conflict {
+		err := fmt.Errorf("Dependency conflict when resolving dependencies: %s in '%s' mode conflicts with %s in '%s' mode.",
+			app.Name,
+			app.Mode.Name,
+			conflictingApp.Name,
+			conflictingApp.Mode.Name)
+
+		return []domain.App{}, err
+	}
+
+	if checkAlreadyIncluded(app, apps) {
+		return apps, nil
 	}
 
 	// All our validation checks have passed, so add the app to the list.
@@ -67,7 +61,7 @@ func add(apps []domain.App, app domain.App, depChain []string) ([]domain.App, er
 			continue
 		}
 
-		startingApps, err = add(startingApps, dep, append(depChain, app.Name))
+		startingApps, err = add(startingApps, dep, skip, append(depChain, app.Name))
 
 		if err != nil {
 			return []domain.App{}, err
@@ -76,3 +70,43 @@ func add(apps []domain.App, app domain.App, depChain []string) ([]domain.App, er
 
 	return startingApps, nil
 }
+
+func checkSkip(appName string, skip []string) bool {
+	for _, s := range skip {
+		if appName == s {
+			return true
+		}
+	}
+
+	return false
+}
+
+func checkCircularDependency(appName string, depChain []string) bool {
+	for _, depName := range depChain {
+		if depName == appName {
+			return true
+		}
+	}
+
+	return false
+}
+
+func checkDependencyConflict(app domain.App, apps []domain.App) (bool, domain.App) {
+	for _, a := range apps {
+		if a.Name == app.Name && a.Mode.Name != app.Mode.Name {
+			return true, a
+		}
+	}
+
+	return false, domain.App{}
+}
+
+func checkAlreadyIncluded(app domain.App, apps []domain.App) bool {
+	for _, a := range apps {
+		if a.Name == app.Name && a.Mode.Name == app.Mode.Name {
+			return true
+		}
+	}
+
+	return false
+}

resolver/resolver_test.go

@@ -25,7 +25,7 @@ func TestAdd(t *testing.T) {
 		},
 	}
 
-	actual, err := Add(apps, app)
+	actual, err := Add(apps, app, []string{})
 
 	if err != nil {
 		t.Errorf("Error: %v\n", err)
@@ -60,7 +60,7 @@ func TestAdd(t *testing.T) {
 		},
 	}
 
-	actual, err = Add(apps, appWithDependencies)
+	actual, err = Add(apps, appWithDependencies, []string{})
 
 	expectedAppNames = []string{
 		"testfenster",
@@ -94,7 +94,7 @@ func TestAdd(t *testing.T) {
 		},
 	}
 
-	_, expectedErr := Add(apps, appWithCircularDependency)
+	_, expectedErr := Add(apps, appWithCircularDependency, []string{})
 
 	if expectedErr == nil {
 		t.Errorf("Expected a circular dependency to result in an error, but it didn't.")
@@ -119,9 +119,31 @@ func TestAdd(t *testing.T) {
 		},
 	}
 
-	_, expectedErr = Add(apps, conflictingApp)
+	_, expectedErr = Add(apps, conflictingApp, []string{})
 
 	if expectedErr == nil {
 		t.Errorf("Expected a conflicting dependency (same name, different mode) to result in an error, but it didn't.")
 	}
+
+	// Declines to add apps from the skip list
+	skippedApp := domain.App{
+		Name: "skipme",
+		Mode: domain.Mode{
+			Name: "dependency",
+		},
+	}
+
+	apps = []domain.App{}
+
+	skip := []string{"skipme"}
+
+	actualApps, err := Add(apps, skippedApp, skip)
+
+	if err != nil {
+		t.Error(err)
+	}
+
+	if len(actualApps) != 0 {
+		t.Errorf("Expected an app appearing in the skip list to be skipped, but it wasn't.")
+	}
 }