Remove abstract modifier from CommandLineParser and eliminate redundant _actions field (#5587)

* Initial plan

* Remove abstract modifier from CommandLineParser and remove redundant _actions array

Co-authored-by: dmichon-msft <26827560+dmichon-msft@users.noreply.github.com>

* Add rush change file for ts-command-line patch

Co-authored-by: dmichon-msft <26827560+dmichon-msft@users.noreply.github.com>

* Revise change file

Co-authored-by: Ian Clanton-Thuon <iclanton@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: dmichon-msft <26827560+dmichon-msft@users.noreply.github.com>
Co-authored-by: David Michon <dmichon@microsoft.com>
Co-authored-by: Ian Clanton-Thuon <iclanton@users.noreply.github.com>

Author: 3 people

common/changes/@rushstack/ts-command-line/copilot-remove-abstract-modifier-commandlineparser_2026-02-03-01-07.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@rushstack/ts-command-line",
+      "comment": "Remove `abstract` modifier from `CommandLineParser` class to allow direct instantiation. Remove redundant `_actions` array field.",
+      "type": "minor"
+    }
+  ],
+  "packageName": "@rushstack/ts-command-line"
+}

common/reviews/api/ts-command-line.api.md

@@ -249,7 +249,7 @@ export abstract class CommandLineParameterWithArgument extends CommandLineParame
 }
 
 // @public
-export abstract class CommandLineParser extends CommandLineParameterProvider {
+export class CommandLineParser extends CommandLineParameterProvider {
     constructor(options: ICommandLineParserOptions);
     get actions(): ReadonlyArray<CommandLineAction>;
     addAction(action: CommandLineAction): void;

libraries/ts-command-line/src/providers/CommandLineParser.ts

@@ -48,13 +48,13 @@ export interface ICommandLineParserOptions {
  * The "argparse" library is a relatively advanced command-line parser with features such
  * as word-wrapping and intelligible error messages (that are lacking in other similar
  * libraries such as commander, yargs, and nomnom).  Unfortunately, its ruby-inspired API
- * is awkward to use.  The abstract base classes CommandLineParser and CommandLineAction
+ * is awkward to use.  The base classes CommandLineParser and CommandLineAction
  * provide a wrapper for "argparse" that makes defining and consuming arguments quick
  * and simple, and enforces that appropriate documentation is provided for each parameter.
  *
  * @public
  */
-export abstract class CommandLineParser extends CommandLineParameterProvider {
+export class CommandLineParser extends CommandLineParameterProvider {
   /**
    * Reports which CommandLineAction was specified on the command line.
    * @remarks
@@ -65,7 +65,6 @@ export abstract class CommandLineParser extends CommandLineParameterProvider {
   private readonly _argumentParser: argparse.ArgumentParser;
   private _actionsSubParser: argparse.SubParser | undefined;
   private readonly _options: ICommandLineParserOptions;
-  private readonly _actions: CommandLineAction[];
   private readonly _actionsByName: Map<string, CommandLineAction>;
   private _executed: boolean = false;
   private _tabCompleteActionWasAdded: boolean = false;
@@ -74,7 +73,6 @@ export abstract class CommandLineParser extends CommandLineParameterProvider {
     super();
 
     this._options = options;
-    this._actions = [];
     this._actionsByName = new Map<string, CommandLineAction>();
 
     const { toolFilename, toolDescription, toolEpilog } = options;
@@ -95,7 +93,7 @@ export abstract class CommandLineParser extends CommandLineParameterProvider {
    * Returns the list of actions that were defined for this CommandLineParser object.
    */
   public get actions(): ReadonlyArray<CommandLineAction> {
-    return this._actions;
+    return Array.from(this._actionsByName.values());
   }
 
   /**
@@ -110,7 +108,6 @@ export abstract class CommandLineParser extends CommandLineParameterProvider {
     }
 
     action._buildParser(this._actionsSubParser);
-    this._actions.push(action);
     this._actionsByName.set(action.actionName, action);
   }
 
@@ -314,7 +311,7 @@ export abstract class CommandLineParser extends CommandLineParameterProvider {
       ...state,
       parentParameterNames: updatedParentParameterNames
     };
-    for (const action of this._actions) {
+    for (const action of this._actionsByName.values()) {
       action._registerDefinedParameters(parentState);
     }
   }

libraries/ts-command-line/src/test/CommandLineParser.test.ts

@@ -58,4 +58,22 @@ describe(CommandLineParser.name, () => {
     const action: TestAction = commandLineParser.selectedAction as TestAction;
     expect(action.done).toBe(true);
   });
+
+  it('can be instantiated directly without subclassing', () => {
+    // This test verifies that CommandLineParser can be instantiated directly,
+    // which is useful for test scenarios
+    const commandLineParser = new CommandLineParser({
+      toolFilename: 'test-tool',
+      toolDescription: 'A test tool'
+    });
+
+    expect(commandLineParser).toBeDefined();
+    expect(commandLineParser.actions).toEqual([]);
+
+    // Verify that addAction can be called on the direct instance
+    const action = new TestAction();
+    commandLineParser.addAction(action);
+    expect(commandLineParser.actions).toHaveLength(1);
+    expect(commandLineParser.actions[0]).toBe(action);
+  });
 });