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      1 // Copyright 2016 the V8 project authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 // Flags: --harmony-string-padding
      6 
      7 (function TestMeta() {
      8   assertEquals(1, String.prototype.padStart.length);
      9   assertEquals("function", typeof String.prototype.padStart);
     10   assertEquals(Object.getPrototypeOf(Function),
     11                Object.getPrototypeOf(String.prototype.padStart));
     12   assertEquals("padStart", String.prototype.padStart.name);
     13 
     14   var desc = Object.getOwnPropertyDescriptor(String.prototype, "padStart");
     15   assertFalse(desc.enumerable);
     16   assertTrue(desc.configurable);
     17   assertTrue(desc.writable);
     18   assertEquals(undefined, desc.get);
     19   assertEquals(undefined, desc.set);
     20 
     21   assertThrows(() => new Function(`${String.prototype.padStart}`), SyntaxError);
     22 })();
     23 
     24 
     25 (function TestRequireObjectCoercible() {
     26   var padStart = String.prototype.padStart;
     27   assertThrows(() => padStart.call(null, 4, "test"), TypeError);
     28   assertThrows(() => padStart.call(undefined, 4, "test"), TypeError);
     29   assertEquals("   123", padStart.call({
     30     __proto__: null,
     31     valueOf() { return 123; }
     32   }, 6, " "));
     33 
     34   var proxy = new Proxy({}, {
     35     get(t, name) {
     36       if (name === Symbol.toPrimitive || name === "toString") return;
     37       if (name === "valueOf") return () => 6.7;
     38       assertUnreachable();
     39     }
     40   });
     41   assertEquals("   6.7", padStart.call(proxy, 6, " "));
     42 
     43   proxy = new Proxy({}, {
     44     get(t, name) {
     45       if (name === Symbol.toPrimitive || name === "valueOf") return;
     46       if (name === "toString") return () => 6.7;
     47       assertUnreachable();
     48     }
     49   });
     50   assertEquals("   6.7", padStart.call(proxy, 6, " "));
     51 })();
     52 
     53 
     54 (function TestToLength() {
     55   assertThrows(() => "123".padStart(Symbol("16")), TypeError);
     56   assertEquals("123", "123".padStart(-1));
     57   assertEquals("123", "123".padStart({ toString() { return -1; } }));
     58   assertEquals("123", "123".padStart(-0));
     59   assertEquals("123", "123".padStart({ toString() { return -0; } }));
     60   assertEquals("123", "123".padStart(+0));
     61   assertEquals("123", "123".padStart({ toString() { return +0; } }));
     62   assertEquals("123", "123".padStart(NaN));
     63   assertEquals("123", "123".padStart({ toString() { return NaN; } }));
     64 })();
     65 
     66 
     67 (function TestFillerToString() {
     68   assertEquals("         .", ".".padStart(10));
     69   assertEquals("         .", ".".padStart(10, undefined));
     70   assertEquals("nullnulln.", ".".padStart(10, null));
     71   assertEquals("XXXXXXXXX.", ".".padStart(10, { toString() { return "X"; } }));
     72   assertEquals(
     73       "111111111.",
     74       ".".padStart(10, { toString: undefined, valueOf() { return 1; } }));
     75 })();
     76 
     77 
     78 (function TestFillerEmptyString() {
     79   assertEquals(".", ".".padStart(10, ""));
     80   assertEquals(".", ".".padStart(10, { toString() { return ""; } }));
     81   assertEquals(
     82       ".", ".".padStart(10, { toString: undefined, valueOf() { return ""; } }));
     83 })();
     84 
     85 
     86 (function TestFillerRepetition() {
     87   for (var i = 2000; i > 0; --i) {
     88     var expected = "xoxo".repeat(i / 4).slice(0, i - 3) + "123";
     89     var actual = "123".padStart(i, "xoxo");
     90     assertEquals(expected, actual);
     91     assertEquals(i > "123".length ? i : 3, actual.length);
     92   }
     93 })();
     94 
     95 
     96 (function TestTruncation() {
     97   assertEquals("ba", "a".padStart(2, "bc"));
     98 })();
     99