process: add NODE_NO_WARNINGS environment variable

This commit adds support for a NODE_NO_WARNINGS environment
variable, which duplicates the functionality of the --no-warnings
command line flag.

Fixes: https://github.com/nodejs/node/issues/10802
PR-URL: https://github.com/nodejs/node/pull/10842
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Italo A. Casas <me@italoacasas.com>

1 files changed, 41 insertions, 0 deletions

diff --git a/test/parallel/test-env-var-no-warnings.js b/test/parallel/test-env-var-no-warnings.js
new file mode 100644
index 0000000000..53b7d30268
--- /dev/null
+++ b/test/parallel/test-env-var-no-warnings.js
@@ -0,0 +1,41 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const cp = require('child_process');
+
+if (process.argv[2] === 'child') {
+  process.emitWarning('foo');
+} else {
+  function test(env) {
+    const cmd = `${process.execPath} ${__filename} child`;
+
+    cp.exec(cmd, { env }, common.mustCall((err, stdout, stderr) => {
+      assert.strictEqual(err, null);
+      assert.strictEqual(stdout, '');
+
+      if (env.NODE_NO_WARNINGS === '1')
+        assert.strictEqual(stderr, '');
+      else
+        assert(/Warning: foo$/.test(stderr.trim()));
+    }));
+  }
+
+  test({});
+  test(process.env);
+  test({ NODE_NO_WARNINGS: undefined });
+  test({ NODE_NO_WARNINGS: null });
+  test({ NODE_NO_WARNINGS: 'foo' });
+  test({ NODE_NO_WARNINGS: true });
+  test({ NODE_NO_WARNINGS: false });
+  test({ NODE_NO_WARNINGS: {} });
+  test({ NODE_NO_WARNINGS: [] });
+  test({ NODE_NO_WARNINGS: function() {} });
+  test({ NODE_NO_WARNINGS: 0 });
+  test({ NODE_NO_WARNINGS: -1 });
+  test({ NODE_NO_WARNINGS: '0' });
+  test({ NODE_NO_WARNINGS: '01' });
+  test({ NODE_NO_WARNINGS: '2' });
+  // Don't test the number 1 because it will come through as a string in the
+  // the child process environment.
+  test({ NODE_NO_WARNINGS: '1' });
+}