Rework color detection (#87)

* add node v20 to the testing matrix

* use process.stdout.isTTY instead of require

* properly test env variables

* adding empty NO_COLOR test

* github actions again?

* remove unnecessary alias

* make nonempty testing easier since env variables always string|undefined

.github/workflows/testing.yaml

@@ -13,6 +13,7 @@ jobs:
     strategy:
       matrix:
         node-version:
+          - 20
           - 18
           - 16
           - 14

picocolors.js

@@ -1,12 +1,13 @@
-let argv = process.argv || [],
-	env = process.env
+let p = process || {},
+	argv = p.argv || [],
+	env = p.env || {}
 let isColorSupported =
-	!("NO_COLOR" in env || argv.includes("--no-color")) &&
-	("FORCE_COLOR" in env ||
+	!(!!env.NO_COLOR || argv.includes("--no-color")) &&
+	(!!env.FORCE_COLOR ||
 		argv.includes("--color") ||
-		process.platform === "win32" ||
-		(require != null && require("tty").isatty(1) && env.TERM !== "dumb") ||
-		"CI" in env)
+		p.platform === "win32" ||
+		((p.stdout || {}).isTTY && env.TERM !== "dumb") ||
+		!!env.CI)
 
 let formatter =
 	(open, close, replace = open) =>

tests/environments.js

@@ -3,6 +3,7 @@ let fs = require("fs")
 let pc = require("../picocolors.js")
 let assert = require("assert")
 let source = fs.readFileSync(__dirname + "/../picocolors.js", "utf-8")
+let CI = process.env.CI
 
 test("ci server", () => {
 	let pc = initModuleEnv({ env: { TERM: "dumb", CI: "1" } })
@@ -22,6 +23,12 @@ test("env NO_COLOR", () => {
 	assert.equal(pc.red("text"), pc.createColors(false).red("text"))
 })
 
+test("env NO_COLOR empty", () => {
+	let pc = initModuleEnv({ env: { NO_COLOR: "", CI } })
+	assert.equal(pc.isColorSupported, true)
+	assert.equal(pc.red("text"), pc.createColors(true).red("text"))
+})
+
 test("env FORCE_COLOR", () => {
 	let pc = initModuleEnv({ env: { TERM: "dumb", FORCE_COLOR: "1" } })
 	assert.equal(pc.isColorSupported, true)
@@ -62,8 +69,14 @@ function test(name, fn) {
 	}
 }
 
-function initModuleEnv({ env, argv = [], platform = "darwin", require = global.require }) {
-	let process = { env, argv, platform }
+function initModuleEnv({
+	env,
+	argv = [],
+	platform = "darwin",
+	require = global.require,
+	stdout = process.stdout,
+}) {
+	let process = { env, argv, platform, stdout }
 	let context = vm.createContext({ require, process, module: { exports: {} } })
 	let script = new vm.Script(source)
 	script.runInContext(context)