tty: add hasColors function

This adds a small wrapper around the `getColorDepth` function to check
if the stream supports at least a specific amount of colors. This is
convenient as the other API is not as straight forward and most use
cases likely only want to know if a specific amount of colors is
supported or not.

PR-URL: https://github.com/nodejs/node/pull/26247
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Weijia Wang <starkwang@126.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>

2 files changed, 22 insertions, 0 deletions

diff --git a/test/pseudo-tty/test-tty-get-color-depth.js b/test/pseudo-tty/test-tty-color-support.js
index 14151ec3fb..b5bc3aca24 100644
--- a/test/pseudo-tty/test-tty-get-color-depth.js
+++ b/test/pseudo-tty/test-tty-color-support.js
@@ -12,8 +12,26 @@ const writeStream = new WriteStream(fd);
   const depth = writeStream.getColorDepth();
   assert.strictEqual(typeof depth, 'number');
   assert(depth >= 1 && depth <= 24);
+
+  const support = writeStream.hasColors();
+  assert.strictEqual(support, depth !== 1);
 }
 
+// Validate invalid input.
+[true, null, () => {}, Symbol(), 5n].forEach((input) => {
+  assert.throws(
+    () => writeStream.hasColors(input),
+    { code: 'ERR_INVALID_ARG_TYPE' }
+  );
+});
+
+[-1, 1].forEach((input) => {
+  assert.throws(
+    () => writeStream.hasColors(input),
+    { code: 'ERR_OUT_OF_RANGE' }
+  );
+});
+
 // Check different environment variables.
 [
   [{ COLORTERM: '1' }, 4],
@@ -54,6 +72,10 @@ const writeStream = new WriteStream(fd);
     `i: ${i}, expected: ${depth}, ` +
       `actual: ${actual}, env: ${inspect(env)}`
   );
+  const colors = 2 ** actual;
+  assert(writeStream.hasColors(colors, env));
+  assert(!writeStream.hasColors(colors + 1, env));
+  assert(depth >= 4 ? writeStream.hasColors(env) : !writeStream.hasColors(env));
 });
 
 // OS settings
diff --git a/test/pseudo-tty/test-tty-get-color-depth.out b/test/pseudo-tty/test-tty-color-support.out
index e69de29bb2..e69de29bb2 100644
--- a/test/pseudo-tty/test-tty-get-color-depth.out
+++ b/test/pseudo-tty/test-tty-color-support.out