Bug 1317397: Only set lastIndex for global or sticky RegExps in RegExpBuiltinExec per ES2017

1 files changed, 80 insertions, 0 deletions

diff --git a/js/src/tests/ecma_2017/lastIndex-exec.js b/js/src/tests/ecma_2017/lastIndex-exec.js
new file mode 100644
index 000000000..f42facbe3
--- /dev/null
+++ b/js/src/tests/ecma_2017/lastIndex-exec.js
@@ -0,0 +1,80 @@
+// RegExp.prototype.exec: Test lastIndex changes for ES2017.
+
+// Test various combinations of:
+// - Pattern matches or doesn't match
+// - Global and/or sticky flag is set.
+// - lastIndex exceeds the input string length
+// - lastIndex is +-0
+const testCases = [
+    { regExp: /a/,  lastIndex: 0, input: "a", result: 0 },
+    { regExp: /a/g, lastIndex: 0, input: "a", result: 1 },
+    { regExp: /a/y, lastIndex: 0, input: "a", result: 1 },
+
+    { regExp: /a/,  lastIndex: 0, input: "b", result: 0 },
+    { regExp: /a/g, lastIndex: 0, input: "b", result: 0 },
+    { regExp: /a/y, lastIndex: 0, input: "b", result: 0 },
+
+    { regExp: /a/,  lastIndex: -0, input: "a", result: -0 },
+    { regExp: /a/g, lastIndex: -0, input: "a", result: 1 },
+    { regExp: /a/y, lastIndex: -0, input: "a", result: 1 },
+
+    { regExp: /a/,  lastIndex: -0, input: "b", result: -0 },
+    { regExp: /a/g, lastIndex: -0, input: "b", result: 0 },
+    { regExp: /a/y, lastIndex: -0, input: "b", result: 0 },
+
+    { regExp: /a/,  lastIndex: -1, input: "a", result: -1 },
+    { regExp: /a/g, lastIndex: -1, input: "a", result: 1 },
+    { regExp: /a/y, lastIndex: -1, input: "a", result: 1 },
+
+    { regExp: /a/,  lastIndex: -1, input: "b", result: -1 },
+    { regExp: /a/g, lastIndex: -1, input: "b", result: 0 },
+    { regExp: /a/y, lastIndex: -1, input: "b", result: 0 },
+
+    { regExp: /a/,  lastIndex: 100, input: "a", result: 100 },
+    { regExp: /a/g, lastIndex: 100, input: "a", result: 0 },
+    { regExp: /a/y, lastIndex: 100, input: "a", result: 0 },
+];
+
+// Basic test.
+for (let {regExp, lastIndex, input, result} of testCases) {
+    let re = new RegExp(regExp);
+    re.lastIndex = lastIndex;
+    re.exec(input);
+    assertEq(re.lastIndex, result);
+}
+
+// Test when lastIndex is non-writable.
+for (let {regExp, lastIndex, input} of testCases) {
+    let re = new RegExp(regExp);
+    Object.defineProperty(re, "lastIndex", { value: lastIndex, writable: false });
+    if (re.global || re.sticky) {
+        assertThrowsInstanceOf(() => re.exec(input), TypeError);
+    } else {
+        re.exec(input);
+    }
+    assertEq(re.lastIndex, lastIndex);
+}
+
+// Test when lastIndex is changed to non-writable as a side-effect.
+for (let {regExp, lastIndex, input} of testCases) {
+    let re = new RegExp(regExp);
+    let called = false;
+    re.lastIndex = {
+        valueOf() {
+            assertEq(called, false);
+            called = true;
+            Object.defineProperty(re, "lastIndex", { value: 9000, writable: false });
+            return lastIndex;
+        }
+    };
+    if (re.global || re.sticky) {
+        assertThrowsInstanceOf(() => re.exec(input), TypeError);
+    } else {
+        re.exec(input);
+    }
+    assertEq(re.lastIndex, 9000);
+    assertEq(called, true);
+}
+
+if (typeof reportCompare === "function")
+    reportCompare(true, true);