fix(complete): keep a partial command expanding to its full name

Registering the requested alias made it a suggestion of its own, so
`webpack b<TAB>` offered `build` and `b` and the shell, having two
candidates, left the word at their common prefix instead of writing
`build` out. The last word is the one being typed, so only the words
before it name the command an alias has to resolve.

Co-authored-by: AmirSa12 <amirhosseinpr184@gmail.com>

Author: alexander-akait

packages/webpack-cli/src/webpack-cli.ts

@@ -2643,8 +2643,10 @@ class WebpackCLI {
       };
     }
 
-    // The command being completed, e.g. `b` in `complete -- b --mode=`.
-    const requested = words.find((word) => word !== "--" && !word.startsWith("-"));
+    // The command already typed, e.g. `b` in `complete -- b --mode=`. The last word
+    // is still being written — `complete -- b` is completing `b` itself, which must
+    // stay a prefix of `build` so the shell expands it instead of matching an alias.
+    const requested = words.slice(0, -1).find((word) => word !== "--" && !word.startsWith("-"));
 
     for (const command of this.program.commands) {
       const tabCommand = completion.commands.get(command.name());

test/complete/complete.test.js

@@ -70,6 +70,23 @@ describe("complete", () => {
     expect(suggestions).toEqual(expect.arrayContaining(["json", "markdown"]));
   });
 
+  it("should expand a partial command to a single suggestion", async () => {
+    // `webpack b<TAB>` has to offer `build` alone, so the shell writes it out;
+    // suggesting the alias `b` next to it would leave the word as typed.
+    for (const [typed, command] of [
+      ["b", "build"],
+      ["w", "watch"],
+      ["s", "serve"],
+      ["i", "info"],
+    ]) {
+      const { exitCode, stderr, stdout } = await run(__dirname, ["complete", "--", typed]);
+
+      expect(exitCode).toBe(0);
+      expect(stderr).toBeFalsy();
+      expect(parseCompletions(stdout)).toEqual([command]);
+    }
+  });
+
   it("should suggest the same options for a command alias", async () => {
     const { stdout: canonical } = await run(__dirname, ["complete", "--", "build", "--"]);