feat(commander): support positional argument completions

.changeset/cold-eggs-wonder.md

@@ -0,0 +1,5 @@
+---
+'@bomb.sh/tab': patch
+---
+
+feat(commander): support completions for positional arguments

examples/demo.commander.ts

@@ -81,6 +81,14 @@ program
     console.log('Linting files...');
   });
 
+// Command with multiple required positional arguments
+program
+  .command('copy <source> <destination>')
+  .description('Copy files')
+  .action((source, destination) => {
+    console.log(`Copying ${source} to ${destination}...`);
+  });
+
 // Initialize tab completion
 const completion = tab(program);
 
@@ -129,5 +137,38 @@ if (devCommandInstance) {
   }
 }
 
+// Positional arguments on lint command
+const lintCommandInstance = completion.commands.get('lint');
+if (lintCommandInstance) {
+  const filesArg = lintCommandInstance.arguments.get('files');
+  if (filesArg) {
+    filesArg.handler = (complete) => {
+      complete('main.ts', 'Main file');
+      complete('index.ts', 'Index file');
+    };
+  }
+}
+
+// Positional arguments on copy command
+const copyCommandInstance = completion.commands.get('copy');
+if (copyCommandInstance) {
+  const sourceArg = copyCommandInstance.arguments.get('source');
+  if (sourceArg) {
+    sourceArg.handler = (complete) => {
+      complete('src/', 'Source directory');
+      complete('dist/', 'Distribution directory');
+      complete('public/', 'Public assets');
+    };
+  }
+  const destinationArg = copyCommandInstance.arguments.get('destination');
+  if (destinationArg) {
+    destinationArg.handler = (complete) => {
+      complete('build/', 'Build output');
+      complete('release/', 'Release directory');
+      complete('backup/', 'Backup location');
+    };
+  }
+}
+
 // Parse command line arguments
 program.parse();

src/commander.ts

@@ -1,5 +1,5 @@
 import type { Command as CommanderCommand } from 'commander';
-import t, { type RootCommand } from './t';
+import t, { Command as TabCommand, type RootCommand } from './t';
 
 // rawArgs is available on (just) the Commander root command, but is not included in the TypeScript types.
 interface CommandWithRawArgs extends CommanderCommand {
@@ -165,6 +165,25 @@
       registerOption(t, flags, longFlag, option.description || '', shortFlag);
     }
   }
+
+  processArguments(t, command);
+}
+
+function processArguments(tabCommand: TabCommand, cmd: CommanderCommand): void {
+  for (const arg of cmd.registeredArguments) {
+    const choices = arg.argChoices;
+    if (choices?.length) {
+      tabCommand.argument(
+        arg.name(),
+        (complete) => {
+          for (const choice of choices) complete(choice, '');
+        },
+        arg.variadic
+      );
+    } else {
+      tabCommand.argument(arg.name(), undefined, arg.variadic);
+    }
+  }
 }
 
 function processSubcommands(rootCommand: CommanderCommand): void {
@@ -198,6 +217,8 @@
         );
       }
     }
+
+    processArguments(command, cmd);
   }
 }
 

tests/__snapshots__/cli.test.ts.snap

@@ -717,6 +717,35 @@ exports[`cli completion tests for commander > cli option value handling > should
 "
 `;
 
+exports[`cli completion tests for commander > copy command argument handlers > should complete destination argument with build suggestions 1`] = `
+"build/	Build output
+release/	Release directory
+backup/	Backup location
+:4
+"
+`;
+
+exports[`cli completion tests for commander > copy command argument handlers > should complete source argument with directory suggestions 1`] = `
+"src/	Source directory
+dist/	Distribution directory
+public/	Public assets
+:4
+"
+`;
+
+exports[`cli completion tests for commander > copy command argument handlers > should filter destination suggestions when typing partial input 1`] = `
+"build/	Build output
+backup/	Backup location
+:4
+"
+`;
+
+exports[`cli completion tests for commander > copy command argument handlers > should filter source suggestions when typing partial input 1`] = `
+"src/	Source directory
+:4
+"
+`;
+
 exports[`cli completion tests for commander > edge case completions for end with space > should keep suggesting the --port option if user typed partial but didn't end with space 1`] = `
 "--port	Specify port
 :4
@@ -737,6 +766,84 @@ exports[`cli completion tests for commander > edge case completions for end with
 "
 `;
 
+exports[`cli completion tests for commander > lint command argument handlers > should complete files argument with file suggestions 1`] = `
+"main.ts	Main file
+index.ts	Index file
+:4
+"
+`;
+
+exports[`cli completion tests for commander > lint command argument handlers > should continue completing variadic files argument after first file 1`] = `
+"main.ts	Main file
+index.ts	Index file
+:4
+"
+`;
+
+exports[`cli completion tests for commander > lint command argument handlers > should continue completing variadic suggestions after first file 1`] = `
+"index.ts	Index file
+:4
+"
+`;
+
+exports[`cli completion tests for commander > lint command argument handlers > should filter file suggestions when typing partial input 1`] = `
+"main.ts	Main file
+:4
+"
+`;
+
+exports[`cli completion tests for commander > positional argument completions > should complete multiple positional arguments when ending with part of the value 1`] = `
+"index.ts	Index file
+:4
+"
+`;
+
+exports[`cli completion tests for commander > positional argument completions > should complete multiple positional arguments when ending with space 1`] = `
+"main.ts	Main file
+index.ts	Index file
+:4
+"
+`;
+
+exports[`cli completion tests for commander > positional argument completions > should complete single positional argument when ending with space 1`] = `
+"main.ts	Main file
+index.ts	Index file
+:4
+"
+`;
+
+exports[`cli completion tests for commander > root command argument tests > should complete root command project argument 1`] = `
+"dev	Start dev server
+serve	Start the server
+build	Build the project
+deploy	Deploy the application
+lint	Lint source files
+copy	Copy files
+:4
+"
+`;
+
+exports[`cli completion tests for commander > root command argument tests > should complete root command project argument after options 1`] = `
+"dev	Start dev server
+serve	Start the server
+build	Build the project
+deploy	Deploy the application
+lint	Lint source files
+copy	Copy files
+:4
+"
+`;
+
+exports[`cli completion tests for commander > root command argument tests > should complete root command project argument with options and partial input 1`] = `
+":4
+"
+`;
+
+exports[`cli completion tests for commander > root command argument tests > should complete root command project argument with partial input 1`] = `
+":4
+"
+`;
+
 exports[`cli completion tests for commander > root command option tests > should complete root command --logLevel option values 1`] = `
 "info	Info level
 warn	Warn level
@@ -829,6 +936,7 @@ serve	Start the server
 build	Build the project
 deploy	Deploy the application
 lint	Lint source files
+copy	Copy files
 :4
 "
 `;

tests/cli.test.ts

@@ -16,9 +16,6 @@ function runCommand(command: string): Promise<string> {
 const cliTools = ['t', 'citty', 'cac', 'commander'];
 
 describe.each(cliTools)('cli completion tests for %s', (cliTool) => {
-  // Commander does not have custom completions for arguments yet.
-  const shouldSkipTest = cliTool === 'commander';
-
   const commandPrefix = `pnpm tsx examples/demo.${cliTool}.ts complete --`;
 
   it('should complete cli options', async () => {
@@ -230,7 +227,7 @@ describe.each(cliTools)('cli completion tests for %s', (cliTool) => {
     });
   });
 
-  describe.runIf(!shouldSkipTest)('root command argument tests', () => {
+  describe('root command argument tests', () => {
     it('should complete root command project argument', async () => {
       const command = `${commandPrefix} ""`;
       const output = await runCommand(command);
@@ -352,7 +349,7 @@ describe.each(cliTools)('cli completion tests for %s', (cliTool) => {
     });
   });
 
-  describe.runIf(!shouldSkipTest)('positional argument completions', () => {
+  describe('positional argument completions', () => {
     it('should complete multiple positional arguments when ending with space', async () => {
       const command = `${commandPrefix} lint ""`;
       const output = await runCommand(command);
@@ -372,7 +369,7 @@ describe.each(cliTools)('cli completion tests for %s', (cliTool) => {
     });
   });
 
-  describe.runIf(!shouldSkipTest)('copy command argument handlers', () => {
+  describe('copy command argument handlers', () => {
     it('should complete source argument with directory suggestions', async () => {
       const command = `${commandPrefix} copy ""`;
       const output = await runCommand(command);
@@ -398,7 +395,7 @@ describe.each(cliTools)('cli completion tests for %s', (cliTool) => {
     });
   });
 
-  describe.runIf(!shouldSkipTest)('lint command argument handlers', () => {
+  describe('lint command argument handlers', () => {
     it('should complete files argument with file suggestions', async () => {
       const command = `${commandPrefix} lint ""`;
       const output = await runCommand(command);