feat: autocomplete choices for options

lib/argsert.ts

@@ -73,7 +73,7 @@ export function argsert(
       position += 1;
     });
   } catch (err) {
-    console.warn(err.stack);
+    console.warn((err as Error).stack);
   }
 }
 

lib/completion.ts

@@ -68,6 +68,7 @@ export class Completion implements CompletionInstance {
 
     this.commandCompletions(completions, args, current);
     this.optionCompletions(completions, args, argv, current);
+    this.choicesCompletions(completions, args, argv, current);
     done(null, completions);
   }
 
@@ -82,7 +83,8 @@ export class Completion implements CompletionInstance {
       .getContext().commands;
     if (
       !current.match(/^-/) &&
-      parentCommands[parentCommands.length - 1] !== current
+      parentCommands[parentCommands.length - 1] !== current &&
+      !this.previousArgHasChoices(args)
     ) {
       this.usage.getCommands().forEach(usageCommand => {
         const commandName = parseCommand(usageCommand[0]).cmd;
@@ -105,7 +107,10 @@ export class Completion implements CompletionInstance {
     argv: Arguments,
     current: string
   ) {
-    if (current.match(/^-/) || (current === '' && completions.length === 0)) {
+    if (
+      (current.match(/^-/) || (current === '' && completions.length === 0)) &&
+      !this.previousArgHasChoices(args)
+    ) {
       const options = this.yargs.getOptions();
       const positionalKeys =
         this.yargs.getGroups()[this.usage.getPositionalGroupName()] || [];
@@ -129,6 +134,48 @@ export class Completion implements CompletionInstance {
     }
   }
 
+  private choicesCompletions(
+    completions: string[],
+    args: string[],
+    argv: Arguments,
+    current: string
+  ) {
+    if (this.previousArgHasChoices(args)) {
+      const choices = this.getPreviousArgChoices(args);
+      if (choices && choices.length > 0) {
+        completions.push(...choices);
+      }
+    }
+  }
+
+  private getPreviousArgChoices(args: string[]): string[] | void {
+    if (args.length < 1) return; // no args
+    let previousArg = args[args.length - 1];
+    let filter = '';
+    // use second to last argument if the last one is not an option starting with --
+    if (!previousArg.startsWith('--') && args.length > 1) {
+      filter = previousArg; // use last arg as filter for choices
+      previousArg = args[args.length - 2];
+    }
+    if (!previousArg.startsWith('--')) return; // still no valid arg, abort
+    const previousArgKey = previousArg.replace(/-/g, '');
+
+    const options = this.yargs.getOptions();
+    if (
+      Object.keys(options.key).some(key => key === previousArgKey) &&
+      Array.isArray(options.choices[previousArgKey])
+    ) {
+      return options.choices[previousArgKey].filter(
+        choice => !filter || choice.startsWith(filter)
+      );
+    }
+  }
+
+  private previousArgHasChoices(args: string[]): boolean {
+    const choices = this.getPreviousArgChoices(args);
+    return choices !== undefined && choices.length > 0;
+  }
+
   private argsContainKey(
     args: string[],
     argv: Arguments,

lib/utils/maybe-async-result.ts

@@ -19,7 +19,7 @@ export function maybeAsyncResult<T>(
       ? result.then((result: T) => resultHandler(result))
       : resultHandler(result);
   } catch (err) {
-    return errorHandler(err);
+    return errorHandler(err as Error);
   }
 }
 

test/completion.cjs

@@ -296,6 +296,83 @@ describe('Completion', () => {
       r.logs.should.include('--foo');
       r.logs.should.not.include('bar');
     });
+
+    it('completes choices if previous option requires a choice', () => {
+      process.env.SHELL = '/bin/bash';
+      const r = checkUsage(() => {
+        return yargs([
+          './completion',
+          '--get-yargs-completions',
+          './completion',
+          '--fruit',
+        ])
+          .options({
+            fruit: {
+              describe: 'fruit option',
+              choices: ['apple', 'banana', 'pear'],
+            },
+            amount: {describe: 'amount', type: 'number'},
+          })
+          .completion('completion', false).argv;
+      });
+
+      r.logs.should.have.length(3);
+      r.logs.should.include('apple');
+      r.logs.should.include('banana');
+      r.logs.should.include('pear');
+    });
+
+    it('completes choices if previous option requires a choice and space has been entered', () => {
+      process.env.SHELL = '/bin/bash';
+      const r = checkUsage(() => {
+        return yargs([
+          './completion',
+          '--get-yargs-completions',
+          './completion',
+          '--fruit',
+          '',
+        ])
+          .options({
+            fruit: {
+              describe: 'fruit option',
+              choices: ['apple', 'banana', 'pear'],
+            },
+            amount: {describe: 'amount', type: 'number'},
+          })
+          .completion('completion', false).argv;
+      });
+
+      r.logs.should.have.length(3);
+      r.logs.should.include('apple');
+      r.logs.should.include('banana');
+      r.logs.should.include('pear');
+    });
+
+    it('completes choices if previous option requires a choice and a partial choice has been entered', () => {
+      process.env.SHELL = '/bin/bash';
+      const r = checkUsage(() => {
+        return yargs([
+          './completion',
+          '--get-yargs-completions',
+          './completion',
+          '--fruit',
+          'ap',
+        ])
+          .options({
+            fruit: {
+              describe: 'fruit option',
+              choices: ['apple', 'banana', 'pear'],
+            },
+            amount: {describe: 'amount', type: 'number'},
+          })
+          .completion('completion', false).argv;
+      });
+
+      r.logs.should.have.length(1);
+      r.logs.should.include('apple');
+      r.logs.should.not.include('banana');
+      r.logs.should.not.include('pear');
+    });
   });
 
   describe('generateCompletionScript()', () => {