load(libdir + "asserts.js");

// Add an invalid "localeMatcher" option to Object.prototype, the exact value does not matter,
// any value except "best fit" or "lookup" is okay.
Object.prototype.localeMatcher = "invalid matcher option";

// The Intl API may not be available in the testing environment. Note that |hasOwnProperty("Intl")|
// initializes the Intl API if present, so this if-statement needs to appear after "localeMatcher"
// was added to Object.prototype.
if (this.hasOwnProperty("Intl")) {
    // Intl prototypes are properly initialized despite changed Object.prototype.
    Intl.Collator.prototype.compare("a", "b");
    Intl.NumberFormat.prototype.format(10);
    Intl.DateTimeFormat.prototype.format(new Date);

    // Intl constructors no longer work properly, because "localeMatcher" defaults to the invalid
    // value from Object.prototype. Except for Intl.DateTimeFormat, cf. ECMA-402 ToDateTimeOptions.
    assertThrowsInstanceOf(() => new Intl.Collator(), RangeError);
    assertThrowsInstanceOf(() => new Intl.NumberFormat(), RangeError);
    new Intl.DateTimeFormat().format(new Date);

    // If an explicit "localeMatcher" option is given, the default from Object.prototype is ignored.
    new Intl.Collator(void 0, {localeMatcher: "lookup"}).compare("a", "b");
    new Intl.NumberFormat(void 0, {localeMatcher: "lookup"}).format(10);
    new Intl.DateTimeFormat(void 0, {localeMatcher: "lookup"}).format(new Date);

    delete Object.prototype.localeMatcher;

    // After removing the default option from Object.prototype, everything works again as expected.
    new Intl.Collator().compare("a", "b");
    new Intl.NumberFormat().format(10);
    new Intl.DateTimeFormat().format(new Date);
}