test: split out load-sensitive readline tests

Two test cases in `test-readline-interface` are sensitive to resource
constraints (probably due to `\r` and `\n` not arriving within the
appropriate delay to be treated as a single line ending). Move those
tests to `sequential`.

Fixes: #14674

test/parallel/test-readline-interface.js

@@ -22,6 +22,7 @@
 // Flags: --expose_internals
 'use strict';
 const common = require('../common');
+
 const assert = require('assert');
 const readline = require('readline');
 const internalReadline = require('internal/readline');
@@ -233,43 +234,6 @@ function isWarned(emitter) {
   // sending multiple newlines at once that does not end with a new line
   // and a `end` event(last line is)
 
-  // \r\n should emit one line event, not two
-  {
-    const fi = new FakeInput();
-    const rli = new readline.Interface(
-      { input: fi, output: fi, terminal: terminal }
-    );
-    const expectedLines = ['foo', 'bar', 'baz', 'bat'];
-    let callCount = 0;
-    rli.on('line', function(line) {
-      assert.strictEqual(line, expectedLines[callCount]);
-      callCount++;
-    });
-    fi.emit('data', expectedLines.join('\r\n'));
-    assert.strictEqual(callCount, expectedLines.length - 1);
-    rli.close();
-  }
-
-  // \r\n should emit one line event when split across multiple writes.
-  {
-    const fi = new FakeInput();
-    const rli = new readline.Interface(
-      { input: fi, output: fi, terminal: terminal }
-    );
-    const expectedLines = ['foo', 'bar', 'baz', 'bat'];
-    let callCount = 0;
-    rli.on('line', function(line) {
-      assert.strictEqual(line, expectedLines[callCount]);
-      callCount++;
-    });
-    expectedLines.forEach(function(line) {
-      fi.emit('data', `${line}\r`);
-      fi.emit('data', '\n');
-    });
-    assert.strictEqual(callCount, expectedLines.length);
-    rli.close();
-  }
-
   // \r should behave like \n when alone
   {
     const fi = new FakeInput();

test/sequential/test-readline-interface.js

@@ -0,0 +1,86 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+// Flags: --expose_internals
+'use strict';
+require('../common');
+
+// These test cases are in `sequential` rather than the analogous test file in
+// `parallel` because they become unrelaible under load. The unreliability under
+// load was determined empirically when the test cases were in `parallel` by
+// running:
+//   tools/test.py -j 96 --repeat 192 test/parallel/test-readline-interface.js
+
+const assert = require('assert');
+const readline = require('readline');
+const EventEmitter = require('events').EventEmitter;
+const inherits = require('util').inherits;
+
+function FakeInput() {
+  EventEmitter.call(this);
+}
+inherits(FakeInput, EventEmitter);
+FakeInput.prototype.resume = () => {};
+FakeInput.prototype.pause = () => {};
+FakeInput.prototype.write = () => {};
+FakeInput.prototype.end = () => {};
+
+[ true, false ].forEach(function(terminal) {
+  // sending multiple newlines at once that does not end with a new line
+  // and a `end` event(last line is)
+
+  // \r\n should emit one line event, not two
+  {
+    const fi = new FakeInput();
+    const rli = new readline.Interface(
+      { input: fi, output: fi, terminal: terminal }
+    );
+    const expectedLines = ['foo', 'bar', 'baz', 'bat'];
+    let callCount = 0;
+    rli.on('line', function(line) {
+      assert.strictEqual(line, expectedLines[callCount]);
+      callCount++;
+    });
+    fi.emit('data', expectedLines.join('\r\n'));
+    assert.strictEqual(callCount, expectedLines.length - 1);
+    rli.close();
+  }
+
+  // \r\n should emit one line event when split across multiple writes.
+  {
+    const fi = new FakeInput();
+    const rli = new readline.Interface(
+      { input: fi, output: fi, terminal: terminal }
+    );
+    const expectedLines = ['foo', 'bar', 'baz', 'bat'];
+    let callCount = 0;
+    rli.on('line', function(line) {
+      assert.strictEqual(line, expectedLines[callCount]);
+      callCount++;
+    });
+    expectedLines.forEach(function(line) {
+      fi.emit('data', `${line}\r`);
+      fi.emit('data', '\n');
+    });
+    assert.strictEqual(callCount, expectedLines.length);
+    rli.close();
+  }
+});