fix: respect --no-color and NO_COLOR

The color guard checked argv.noColor, which yargs never sets: --no-color
parses to color=false. It only worked because chalk sniffs process.argv
itself, so FORCE_COLOR overrode it and NO_COLOR was ignored entirely.

Author: firecow

src/argv.ts

@@ -105,7 +105,7 @@ export class Argv {
     }
 
     private constructor (argv: any, writeStreams?: WriteStreams) {
-        if (argv.noColor) {
+        if (argv.noColor || argv.color === false || (process.env.NO_COLOR ?? "") !== "") {
             chalkBase.level = 0;
         }
         this.writeStreams = writeStreams;

tests/argv-color.test.ts

@@ -0,0 +1,51 @@
+import "../src/global.js";
+import chalkBase from "chalk";
+import {Argv} from "../src/argv.js";
+import {WriteStreamsMock} from "../src/write-streams.js";
+
+let writeStreams: WriteStreamsMock;
+let originalLevel: number;
+let originalNoColor: string | undefined;
+
+beforeEach(() => {
+    writeStreams = new WriteStreamsMock();
+    originalLevel = chalkBase.level;
+    originalNoColor = process.env.NO_COLOR;
+});
+
+afterEach(() => {
+    chalkBase.level = originalLevel;
+    if (originalNoColor === undefined) {
+        delete process.env.NO_COLOR;
+    } else {
+        process.env.NO_COLOR = originalNoColor;
+    }
+});
+
+test("color stays enabled by default", async () => {
+    chalkBase.level = 2;
+    delete process.env.NO_COLOR;
+    await Argv.build({}, writeStreams);
+    expect(chalkBase.level).toBe(2);
+});
+
+test("--no-color disables color", async () => {
+    chalkBase.level = 2;
+    delete process.env.NO_COLOR;
+    await Argv.build({color: false}, writeStreams);
+    expect(chalkBase.level).toBe(0);
+});
+
+test("NO_COLOR disables color", async () => {
+    chalkBase.level = 2;
+    process.env.NO_COLOR = "1";
+    await Argv.build({}, writeStreams);
+    expect(chalkBase.level).toBe(0);
+});
+
+test("an empty NO_COLOR leaves color enabled", async () => {
+    chalkBase.level = 2;
+    process.env.NO_COLOR = "";
+    await Argv.build({}, writeStreams);
+    expect(chalkBase.level).toBe(2);
+});