test: improve tty.getColorDepth coverage

PR-URL: nodejs#19446
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Shingo Inoue <leko.noor@gmail.com>

test/pseudo-tty/test-tty-get-color-depth.js

@@ -10,27 +10,55 @@ const writeStream = new WriteStream(fd);
 
 {
   const depth = writeStream.getColorDepth();
-
   assert.equal(typeof depth, 'number');
   assert(depth >= 1 && depth <= 24);
-
-  if (depth === 1) {
-    // Terminal does not support colors, compare to a value that would.
-    assert.notEqual(writeStream.getColorDepth({ COLORTERM: '1' }), depth);
-  } else {
-    // Terminal supports colors, compare to a value that would not.
-    assert.notEqual(writeStream.getColorDepth({ TERM: 'dumb' }), depth);
-  }
 }
 
-// Deactivate colors
-{
-  const tmp = process.env.NODE_DISABLE_COLORS;
-  process.env.NODE_DISABLE_COLORS = 1;
-
-  const depth = writeStream.getColorDepth();
+// Check different environment variables.
+[
+  [{ COLORTERM: '1' }, 4],
+  [{ TMUX: '1' }, 8],
+  [{ CI: '1' }, 1],
+  [{ CI: '1', TRAVIS: '1' }, 8],
+  [{ CI: '1', CIRCLECI: '1' }, 8],
+  [{ CI: '1', APPVEYOR: '1' }, 8],
+  [{ CI: '1', GITLAB_CI: '1' }, 8],
+  [{ CI: '1', CI_NAME: 'codeship' }, 8],
+  [{ TEAMCITY_VERSION: '1.0.0' }, 1],
+  [{ TEAMCITY_VERSION: '9.11.0' }, 4],
+  [{ TERM_PROGRAM: 'iTerm.app' }, 8],
+  [{ TERM_PROGRAM: 'iTerm.app', TERM_PROGRAM_VERSION: '3.0' }, 24],
+  [{ TERM_PROGRAM: 'iTerm.app', TERM_PROGRAM_VERSION: '2.0' }, 8],
+  [{ TERM_PROGRAM: 'HyperTerm' }, 24],
+  [{ TERM_PROGRAM: 'Hyper' }, 24],
+  [{ TERM_PROGRAM: 'MacTerm' }, 24],
+  [{ TERM_PROGRAM: 'Apple_Terminal' }, 8],
+  [{ TERM: 'xterm-256' }, 8],
+  [{ TERM: 'ansi' }, 4],
+  [{ TERM: 'ANSI' }, 4],
+  [{ TERM: 'color' }, 4],
+  [{ TERM: 'linux' }, 4],
+  [{ TERM: 'fail' }, 1],
+  [{ NODE_DISABLE_COLORS: '1' }, 1],
+  [{ TERM: 'dumb' }, 1],
+  [{ TERM: 'dumb', COLORTERM: '1' }, 4],
+].forEach(([env, depth], i) => {
+  const actual = writeStream.getColorDepth(env);
+  assert.equal(
+    actual,
+    depth,
+    `i: ${i}, expected: ${depth}, actual: ${actual}, env: ${env}`
+  );
+});
 
-  assert.equal(depth, 1);
+// OS settings
+{
+  const platform = Object.getOwnPropertyDescriptor(process, 'platform');
+  const [ value, depth1, depth2 ] = process.platform !== 'win32' ?
+    ['win32', 1, 4] : ['linux', 4, 1];
 
-  process.env.NODE_DISABLE_COLORS = tmp;
+  assert.equal(writeStream.getColorDepth({}), depth1);
+  Object.defineProperty(process, 'platform', { value });
+  assert.equal(writeStream.getColorDepth({}), depth2);
+  Object.defineProperty(process, 'platform', platform);
 }