fix(apps): render verb-specific usage and hint in missingAppNameError

The shared zero-arg validator used by deploy/start/stop/delete printed a
hardcoded "databricks apps deploy <hint>" suggestion and a generic
"<command>" placeholder in the usage line, so users running `apps stop`
without an APP_NAME were nudged toward `apps deploy` instead.

- Thread the cobra command into missingAppNameError and render both the
  Usage line and the "Did you mean?" hint from cmd.CommandPath().
- Extend bundle_helpers_test.go with table-driven coverage that exercises
  deploy/start/stop/delete and asserts the hint matches the verb.
- inferAppNameHint now requires app.yml/app.yaml to be a regular file,
  so a directory of that name no longer produces a bogus hint.
- Regenerate the no-bundle-no-args acceptance fixture for the new
  message.

Co-authored-by: Isaac

Author: jamesbroadhead

acceptance/apps/deploy/no-bundle-no-args/output.txt

@@ -1,3 +1,9 @@
-Error: accepts 1 arg(s), received 0
+Error: missing required argument: APP_NAME
+
+Usage: databricks apps deploy APP_NAME
+
+APP_NAME is the name of the Databricks app to operate on.
+Alternatively, run this command from a project directory containing
+databricks.yml to auto-detect the app name.
 
 Exit code: 1

cmd/apps/bundle_helpers.go

@@ -29,26 +29,34 @@ func makeArgsOptionalWithBundle(cmd *cobra.Command, usage string) {
 			return fmt.Errorf("accepts at most 1 arg(s), received %d", len(args))
 		}
 		if !hasBundleConfig() && len(args) != 1 {
-			return missingAppNameError()
+			return missingAppNameError(cmd)
 		}
 		return nil
 	}
 }
 
 // missingAppNameError returns an error message that explains what the positional
 // argument should be, and attempts to infer a suggestion from the local environment.
-func missingAppNameError() error {
+// The full subcommand path (e.g. "databricks apps start") is rendered from cmd so
+// the usage line and "Did you mean?" hint match the verb the user actually ran.
+func missingAppNameError(cmd *cobra.Command) error {
 	hint := inferAppNameHint()
-	msg := `missing required argument: APP_NAME
+	commandPath := "databricks apps <command>"
+	if cmd != nil {
+		if p := cmd.CommandPath(); p != "" {
+			commandPath = p
+		}
+	}
+	msg := fmt.Sprintf(`missing required argument: APP_NAME
 
-Usage: databricks apps <command> APP_NAME
+Usage: %s APP_NAME
 
 APP_NAME is the name of the Databricks app to operate on.
 Alternatively, run this command from a project directory containing
-databricks.yml to auto-detect the app name.`
+databricks.yml to auto-detect the app name.`, commandPath)
 
 	if hint != "" {
-		msg += "\n\nDid you mean?\n  databricks apps deploy " + hint
+		msg += fmt.Sprintf("\n\nDid you mean?\n  %s %s", commandPath, hint)
 	}
 
 	return errors.New(msg)
@@ -64,7 +72,8 @@ func inferAppNameHint() string {
 	}
 
 	for _, filename := range []string{"app.yml", "app.yaml"} {
-		if _, err := os.Stat(filepath.Join(wd, filename)); err == nil {
+		info, err := os.Stat(filepath.Join(wd, filename))
+		if err == nil && info.Mode().IsRegular() {
 			return filepath.Base(wd)
 		}
 	}

cmd/apps/bundle_helpers_test.go

@@ -145,7 +145,7 @@ func TestMissingAppNameError(t *testing.T) {
 	t.Run("includes APP_NAME and usage info", func(t *testing.T) {
 		t.Chdir(t.TempDir())
 
-		err := missingAppNameError()
+		err := missingAppNameError(nil)
 		assert.Contains(t, err.Error(), "APP_NAME")
 		assert.Contains(t, err.Error(), "databricks.yml")
 		assert.NotContains(t, err.Error(), "Did you mean")
@@ -157,7 +157,7 @@ func TestMissingAppNameError(t *testing.T) {
 		writeErr := os.WriteFile(filepath.Join(dir, "app.yml"), []byte("command: [\"python\"]"), 0o644)
 		assert.NoError(t, writeErr)
 
-		err := missingAppNameError()
+		err := missingAppNameError(nil)
 		assert.Contains(t, err.Error(), "Did you mean")
 		assert.Contains(t, err.Error(), filepath.Base(dir))
 	})
@@ -167,10 +167,40 @@ func TestMissingAppNameError(t *testing.T) {
 		t.Chdir(dir)
 		os.Remove(dir)
 
-		err := missingAppNameError()
+		err := missingAppNameError(nil)
 		assert.Contains(t, err.Error(), "APP_NAME")
 		assert.NotContains(t, err.Error(), "Did you mean")
 	})
+
+	t.Run("renders usage and hint from cmd path per verb", func(t *testing.T) {
+		dir := t.TempDir()
+		t.Chdir(dir)
+		writeErr := os.WriteFile(filepath.Join(dir, "app.yml"), []byte("command: [\"python\"]"), 0o644)
+		assert.NoError(t, writeErr)
+
+		for _, verb := range []string{"deploy", "start", "stop", "delete"} {
+			t.Run(verb, func(t *testing.T) {
+				root := &cobra.Command{Use: "databricks"}
+				apps := &cobra.Command{Use: "apps"}
+				sub := &cobra.Command{Use: verb}
+				root.AddCommand(apps)
+				apps.AddCommand(sub)
+
+				err := missingAppNameError(sub)
+				assert.Contains(t, err.Error(), "Usage: databricks apps "+verb+" APP_NAME")
+				assert.Contains(t, err.Error(), "databricks apps "+verb+" "+filepath.Base(dir))
+			})
+		}
+	})
+
+	t.Run("ignores non-regular app.yml entries", func(t *testing.T) {
+		dir := t.TempDir()
+		t.Chdir(dir)
+		assert.NoError(t, os.Mkdir(filepath.Join(dir, "app.yml"), 0o755))
+
+		err := missingAppNameError(nil)
+		assert.NotContains(t, err.Error(), "Did you mean")
+	})
 }
 
 func TestMakeArgsOptionalWithBundle(t *testing.T) {