test/language/expressions: Add nullish coalescing tests

Copies a few tests for nullish coalescing straight from the newest
test262 master branch so that we can test
https://codereview.qt-project.org/c/qt/qtdeclarative/+/283241 .

Change-Id: I312e96c1e2934d2933421371d58bfce670f244ae
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

1 files changed, 61 insertions, 0 deletions

diff --git a/test/language/expressions/coalesce/chainable-if-parenthesis-covered-logical-or.js b/test/language/expressions/coalesce/chainable-if-parenthesis-covered-logical-or.js
new file mode 100644
index 000000000..240613205
--- /dev/null
+++ b/test/language/expressions/coalesce/chainable-if-parenthesis-covered-logical-or.js
@@ -0,0 +1,61 @@
+// Copyright (C) 2019 Leo Balter. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: >
+    CoalesceExpression is chainable with the LogicalORExpression is any is covered.
+esid: sec-conditional-operator
+info: |
+    ConditionalExpression :
+        ShortCircuitExpression
+        ShortCircuitExpression ? AssignmentExpression : AssignmentExpression
+
+    ShortCircuitExpression :
+        LogicalORExpression
+        CoalesceExpression
+
+    CoalesceExpression :
+        CoalesceExpressionHead ?? BitwiseORExpression
+
+    CoalesceExpressionHead :
+        CoalesceExpression
+        BitwiseORExpression
+
+    Runtime Semantics: Evaluation
+
+    CoalesceExpression:CoalesceExpressionHead??BitwiseORExpression
+
+    1. Let lref be the result of evaluating CoalesceExpressionHead.
+    2. Let lval be ? GetValue(lref).
+    3. If lval is undefined or null,
+        a. Let rref be the result of evaluating BitwiseORExpression.
+        b. Return ? GetValue(rref).
+    4. Otherwise, return lval.
+features: [coalesce-expression]
+---*/
+
+var x;
+
+x = undefined;
+x = (null ?? 42) || 43;
+assert.sameValue(x, 42, '(null ?? 42) || 43');
+
+x = undefined;
+x = null ?? (42 || 43);
+assert.sameValue(x, 42, 'null ?? (42 || 43)`');
+
+x = undefined;
+x = (null || 42) ?? 43;
+assert.sameValue(x, 42, '(null || 42) ?? 43');
+
+x = undefined;
+x = null || (42 ?? 43);
+assert.sameValue(x, 42, 'null || (42 ?? 43)`');
+
+x = undefined;
+x = (42 || 43) ?? null;
+assert.sameValue(x, 42, '(42 || 43) ?? null');
+
+x = undefined;
+x = 42 || (null ?? 43);
+assert.sameValue(x, 42, '42 || (null ?? 43)');