Source code
Revision control
Copy as Markdown
Other Tools
// 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);