Add tests for proposal array find from last

test/built-ins/Array/prototype/findLast/array-altered-during-loop.js

@@ -0,0 +1,47 @@
+// Copyright (C) 2021 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-array.prototype.findlast
+description: >
+  The range of elements processed is set before the first call to `predicate`.
+info: |
+  Array.prototype.findLast ( predicate[ , thisArg ] )
+
+  ...
+  3. If IsCallable(predicate) is false, throw a TypeError exception.
+  4. Let k be len - 1.
+  5. Repeat, while k ≥ 0,
+    ...
+    c. Let testResult be ! ToBoolean(? Call(predicate, thisArg, « kValue, 𝔽(k), O »)).
+  ...
+---*/
+
+var arr = ['Shoes', 'Car', 'Bike'];
+var results = [];
+
+arr.findLast(function(kValue) {
+  if (results.length === 0) {
+    arr.splice(1, 1);
+  }
+  results.push(kValue);
+});
+
+assert.sameValue(results.length, 3, 'predicate called three times');
+assert.sameValue(results[0], 'Bike');
+assert.sameValue(results[1], 'Bike');
+assert.sameValue(results[2], 'Shoes');
+
+results = [];
+arr = ['Skateboard', 'Barefoot'];
+arr.find(function(kValue) {
+  if (results.length === 0) {
+    arr.push('Motorcycle');
+    arr[1] = 'Magic Carpet';
+  }
+
+  results.push(kValue);
+});
+
+assert.sameValue(results.length, 2, 'predicate called twice');
+assert.sameValue(results[0], 'Barefoot');
+assert.sameValue(results[1], 'Magic Carpet');

test/built-ins/Array/prototype/findLast/call-with-boolean.js

@@ -0,0 +1,18 @@
+// Copyright (c) 2021 Rick Waldron.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-array.prototype.findlast
+description: Array.prototype.findLast applied to boolean primitive
+---*/
+
+assert.sameValue(
+  Array.prototype.findLast.call(true, () => {}),
+  undefined,
+  'Array.prototype.findLast.call(true, () => {}) must return undefined'
+);
+assert.sameValue(
+  Array.prototype.findLast.call(false, () => {}),
+  undefined,
+  'Array.prototype.findLast.call(false, () => {}) must return undefined'
+);

test/built-ins/Array/prototype/findLast/length.js

@@ -0,0 +1,18 @@
+// Copyright (C) 2021 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-array.prototype.findlast
+description: Array.prototype.findLast.length value and descriptor.
+info: |
+  17 ECMAScript Standard Built-in Objects
+includes: [propertyHelper.js]
+---*/
+
+assert.sameValue(
+  Array.prototype.findLast.length, 1,
+  'The value of `Array.prototype.findLast.length` is `1`'
+);
+
+verifyNotEnumerable(Array.prototype.findLast, 'length');
+verifyNotWritable(Array.prototype.findLast, 'length');
+verifyConfigurable(Array.prototype.findLast, 'length');

test/built-ins/Array/prototype/findLast/name.js

@@ -0,0 +1,22 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-array.prototype.findlast
+description: >
+  Array.prototype.findLast.name value and descriptor.
+info: |
+  Array.prototype.findLast ( predicate [ , thisArg ] )
+
+  17 ECMAScript Standard Built-in Objects
+
+includes: [propertyHelper.js]
+---*/
+
+assert.sameValue(
+  Array.prototype.findLast.name, 'findLast',
+  'The value of `Array.prototype.findLast.name` is `"findLast"`'
+);
+
+verifyNotEnumerable(Array.prototype.findLast, 'name');
+verifyNotWritable(Array.prototype.findLast, 'name');
+verifyConfigurable(Array.prototype.findLast, 'name');

test/built-ins/Array/prototype/findLast/not-a-constructor.js

@@ -0,0 +1,29 @@
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-ecmascript-standard-built-in-objects
+description: >
+  Array.prototype.findLast does not implement [[Construct]], is not new-able
+info: |
+  ECMAScript Function Objects
+
+  Built-in function objects that are not identified as constructors do not
+  implement the [[Construct]] internal method unless otherwise specified in
+  the description of a particular function.
+
+  sec-evaluatenew
+
+  ...
+  7. If IsConstructor(constructor) is false, throw a TypeError exception.
+  ...
+includes: [isConstructor.js]
+features: [Reflect.construct, arrow-function]
+---*/
+
+assert.sameValue(isConstructor(Array.prototype.findLast), false, 'isConstructor(Array.prototype.findLast) must return false');
+
+assert.throws(TypeError, () => {
+  new Array.prototype.findLast(() => {});
+}, '`new Array.prototype.findLast(() => {})` throws TypeError');
+

test/built-ins/Array/prototype/findLast/predicate-call-parameters.js

@@ -0,0 +1,46 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-array.prototype.findlast
+description: >
+  Predicate called as F.call( thisArg, kValue, k, O ) for each array entry.
+info: |
+  Array.prototype.findLast ( predicate[ , thisArg ] )
+
+  ...
+  3. If IsCallable(predicate) is false, throw a TypeError exception.
+  4. Let k be len - 1.
+  5. Repeat, while k ≥ 0,
+    ...
+    c. Let testResult be ! ToBoolean(? Call(predicate, thisArg, « kValue, 𝔽(k), O »)).
+    d. If testResult is true, return kValue.
+  ...
+---*/
+
+var arr = ['Mike', 'Rick', 'Leo'];
+
+var results = [];
+
+arr.findLast(function(kValue, k, O) {
+  results.push(arguments);
+});
+
+assert.sameValue(results.length, 3);
+
+var result = results[0];
+assert.sameValue(result[0], 'Leo');
+assert.sameValue(result[1], 2);
+assert.sameValue(result[2], arr);
+assert.sameValue(result.length, 3);
+
+result = results[1];
+assert.sameValue(result[0], 'Rick');
+assert.sameValue(result[1], 1);
+assert.sameValue(result[2], arr);
+assert.sameValue(result.length, 3);
+
+result = results[2];
+assert.sameValue(result[0], 'Mike');
+assert.sameValue(result[1], 0);
+assert.sameValue(result[2], arr);
+assert.sameValue(result.length, 3);

test/built-ins/Array/prototype/findLast/predicate-call-this-non-strict.js

@@ -0,0 +1,32 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-array.prototype.findlast
+description: >
+  Predicate thisArg as F.call( thisArg, kValue, k, O ) for each array entry.
+info: |
+  Array.prototype.findLast ( predicate[ , thisArg ] )
+
+  ...
+  5. Repeat, while k ≥ 0,
+    ...
+    c. Let testResult be ! ToBoolean(? Call(predicate, thisArg, « kValue, 𝔽(k), O »)).
+    d. If testResult is true, return kValue.
+  ...
+flags: [noStrict]
+---*/
+
+var result;
+
+[1].findLast(function(kValue, k, O) {
+  result = this;
+});
+
+assert.sameValue(result, this);
+
+var o = {};
+[1].findLast(function() {
+  result = this;
+}, o);
+
+assert.sameValue(result, o);

test/built-ins/Array/prototype/findLast/predicate-call-this-strict.js

@@ -0,0 +1,32 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-array.prototype.findlast
+description: >
+  Predicate thisArg as F.call( thisArg, kValue, k, O ) for each array entry.
+info: |
+  Array.prototype.findLast ( predicate[ , thisArg ] )
+
+  ...
+  5. Repeat, while k ≥ 0,
+    ...
+    c. Let testResult be ! ToBoolean(? Call(predicate, thisArg, « kValue, 𝔽(k), O »)).
+    d. If testResult is true, return kValue.
+  ...
+flags: [onlyStrict]
+---*/
+
+var result;
+
+[1].findLast(function(kValue, k, O) {
+  result = this;
+});
+
+assert.sameValue(result, undefined);
+
+var o = {};
+[1].findLast(function() {
+  result = this;
+}, o);
+
+assert.sameValue(result, o);

test/built-ins/Array/prototype/findLast/predicate-called-for-each-array-property.js

@@ -0,0 +1,26 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-array.prototype.findlast
+description: >
+  Predicate is called for each array property.
+info: |
+  Array.prototype.findLast ( predicate[ , thisArg ] )
+
+  ...
+  3. If IsCallable(predicate) is false, throw a TypeError exception.
+  4. Let k be len - 1.
+  5. Repeat, while k ≥ 0,
+    ...
+    c. Let testResult be ! ToBoolean(? Call(predicate, thisArg, « kValue, 𝔽(k), O »)).
+  ...
+---*/
+
+var arr = [undefined, , , 'foo'];
+var called = 0;
+
+arr.findLast(function() {
+  called++;
+});
+
+assert.sameValue(called, 4);

test/built-ins/Array/prototype/findLast/predicate-is-not-callable-throws.js

@@ -0,0 +1,49 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-array.prototype.findlast
+description: >
+  Throws a TypeError exception if predicate is not callable.
+info: |
+  Array.prototype.findLast ( predicate[ , thisArg ] )
+
+  ...
+  3. If IsCallable(predicate) is false, throw a TypeError exception.
+  ...
+---*/
+
+assert.throws(TypeError, function() {
+  [].findLast({});
+});
+
+assert.throws(TypeError, function() {
+  [].findLast(null);
+});
+
+assert.throws(TypeError, function() {
+  [].findLast(undefined);
+});
+
+assert.throws(TypeError, function() {
+  [].findLast(true);
+});
+
+assert.throws(TypeError, function() {
+  [].findLast(1);
+});
+
+assert.throws(TypeError, function() {
+  [].findLast('');
+});
+
+assert.throws(TypeError, function() {
+  [].findLast(1);
+});
+
+assert.throws(TypeError, function() {
+  [].findLast([]);
+});
+
+assert.throws(TypeError, function() {
+  [].findLast(/./);
+});

test/built-ins/Array/prototype/findLast/predicate-not-called-on-empty-array.js

@@ -0,0 +1,29 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-array.prototype.findlast
+description: >
+  Predicate is only called if this.length is > 0.
+info: |
+  Array.prototype.findLast ( predicate[ , thisArg ] )
+
+  ...
+  4. Let k be len - 1.
+  5. Repeat, while k ≥ 0,
+    ...
+    c. Let testResult be ! ToBoolean(? Call(predicate, thisArg, « kValue, 𝔽(k), O »)).
+  ...
+  6. Return undefined.
+---*/
+
+var called = false;
+
+var predicate = function() {
+  called = true;
+  return true;
+};
+
+var result = [].findLast(predicate);
+
+assert.sameValue(called, false, '[].findLast(predicate) does not call predicate');
+assert.sameValue(result, undefined, '[].findLast(predicate) returned undefined');

test/built-ins/Array/prototype/findLast/prop-desc.js

@@ -0,0 +1,19 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-array.prototype.findlast
+description: Property type and descriptor.
+info: |
+  17 ECMAScript Standard Built-in Objects
+includes: [propertyHelper.js]
+---*/
+
+assert.sameValue(
+  typeof Array.prototype.findLast,
+  'function',
+  '`typeof Array.prototype.findLast` is `function`'
+);
+
+verifyNotEnumerable(Array.prototype, 'findLast');
+verifyWritable(Array.prototype, 'findLast');
+verifyConfigurable(Array.prototype, 'findLast');

test/built-ins/Array/prototype/findLast/return-abrupt-from-predicate-call.js

@@ -0,0 +1,25 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-array.prototype.findlast
+description: >
+  Return abrupt from predicate call.
+info: |
+  Array.prototype.findLast ( predicate[ , thisArg ] )
+
+  ...
+  4. Let k be len - 1.
+  5. Repeat, while k ≥ 0,
+    ...
+    c. Let testResult be ! ToBoolean(? Call(predicate, thisArg, « kValue, 𝔽(k), O »)).
+    d. If testResult is true, return kValue.
+  ...
+---*/
+
+var predicate = function() {
+  throw new Test262Error();
+};
+
+assert.throws(Test262Error, function() {
+  [1].findLast(predicate);
+});

test/built-ins/Array/prototype/findLast/return-abrupt-from-property.js

@@ -0,0 +1,32 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-array.prototype.findlast
+description: >
+  Returns abrupt from getting property value from `this`.
+info: |
+  Array.prototype.findLast ( predicate[ , thisArg ] )
+
+  ...
+  4. Let k be len - 1.
+  5. Repeat, while k ≥ 0,
+    a. Let Pk be ! ToString(𝔽(k)).
+    b. Let kValue be ? Get(O, Pk).
+    ...
+    d. If testResult is true, return kValue.
+  ...
+---*/
+
+var o = {
+  length: 1
+};
+
+Object.defineProperty(o, 0, {
+  get: function() {
+    throw new Test262Error();
+  }
+});
+
+assert.throws(Test262Error, function() {
+  [].findLast.call(o, function() {});
+});

test/built-ins/Array/prototype/findLast/return-abrupt-from-this-length-as-symbol.js

@@ -0,0 +1,23 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-array.prototype.findlast
+description: >
+  Return abrupt from ToLength(Get(O, "length")) where length is a Symbol.
+info: |
+  Array.prototype.findLast ( predicate[ , thisArg ] )
+
+  1. Let O be ? ToObject(this value).
+  2. Let len be ? LengthOfArrayLike(O).
+
+features: [Symbol]
+---*/
+
+var o = {};
+
+o.length = Symbol(1);
+
+// predicate fn is given to avoid false positives
+assert.throws(TypeError, function() {
+  [].findLast.call(o, function() {});
+});

test/built-ins/Array/prototype/findLast/return-abrupt-from-this-length.js

@@ -0,0 +1,36 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-array.prototype.findlast
+description: >
+  Return abrupt from ToLength(Get(O, "length")).
+info: |
+  Array.prototype.findLast ( predicate[ , thisArg ] )
+
+  1. Let O be ? ToObject(this value).
+  2. Let len be ? LengthOfArrayLike(O).
+---*/
+
+var o1 = {};
+
+Object.defineProperty(o1, 'length', {
+  get: function() {
+    throw new Test262Error();
+  },
+  configurable: true
+});
+
+assert.throws(Test262Error, function() {
+  [].findLast.call(o1);
+});
+
+var o2 = {
+  length: {
+    valueOf: function() {
+      throw new Test262Error();
+    }
+  }
+};
+assert.throws(Test262Error, function() {
+  [].findLast.call(o2);
+});

test/built-ins/Array/prototype/findLast/return-abrupt-from-this.js

@@ -0,0 +1,20 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-array.prototype.findlast
+description: >
+  Return abrupt from ToObject(this value).
+info: |
+  Array.prototype.findLast ( predicate[ , thisArg ] )
+
+  1. Let O be ? ToObject(this value).
+---*/
+
+// predicate fn is given to avoid false positives
+assert.throws(TypeError, function() {
+  Array.prototype.findLast.call(undefined, function() {});
+});
+
+assert.throws(TypeError, function() {
+  Array.prototype.findLast.call(null, function() {});
+});

test/built-ins/Array/prototype/findLast/return-found-value-predicate-result-is-true.js

@@ -0,0 +1,62 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-array.prototype.findlast
+description: >
+  Return found value if predicate return a boolean true value.
+info: |
+  Array.prototype.findLast ( predicate[ , thisArg ] )
+
+  ...
+  5. Repeat, while k ≥ 0,
+    ...
+    c. Let testResult be ! ToBoolean(? Call(predicate, thisArg, « kValue, 𝔽(k), O »)).
+    d. If testResult is true, return kValue.
+  ...
+features: [Symbol]
+---*/
+
+var arr = ['Shoes', 'Car', 'Bike'];
+var called = 0;
+
+var result = arr.findLast(function(val) {
+  called++;
+  return true;
+});
+
+assert.sameValue(result, 'Bike');
+assert.sameValue(called, 1, 'predicate was called once');
+
+called = 0;
+result = arr.findLast(function(val) {
+  called++;
+  return val === 'Bike';
+});
+
+assert.sameValue(called, 1, 'predicate was called three times');
+assert.sameValue(result, 'Bike');
+
+result = arr.findLast(function(val) {
+  return 'string';
+});
+assert.sameValue(result, 'Bike', 'coerced string');
+
+result = arr.findLast(function(val) {
+  return {};
+});
+assert.sameValue(result, 'Bike', 'coerced object');
+
+result = arr.findLast(function(val) {
+  return Symbol('');
+});
+assert.sameValue(result, 'Bike', 'coerced Symbol');
+
+result = arr.findLast(function(val) {
+  return 1;
+});
+assert.sameValue(result, 'Bike', 'coerced number');
+
+result = arr.findLast(function(val) {
+  return -1;
+});
+assert.sameValue(result, 'Bike', 'coerced negative number');

test/built-ins/Array/prototype/findLast/return-undefined-if-predicate-returns-false-value.js

@@ -0,0 +1,53 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-array.prototype.findlast
+description: >
+  Return undefined if predicate always returns a boolean false value.
+info: |
+  Array.prototype.findLast ( predicate[ , thisArg ] )
+
+  ...
+  5. Repeat, while k ≥ 0,
+    ...
+    c. Let testResult be ! ToBoolean(? Call(predicate, thisArg, « kValue, 𝔽(k), O »)).
+    ...
+  6. Return undefined.
+features: [Symbol]
+---*/
+
+var arr = ['Shoes', 'Car', 'Bike'];
+var called = 0;
+
+var result = arr.findLast(function(val) {
+  called++;
+  return false;
+});
+
+assert.sameValue(called, 3, 'predicate was called three times');
+assert.sameValue(result, undefined);
+
+result = arr.findLast(function(val) {
+  return '';
+});
+assert.sameValue(result, undefined, 'coerced string');
+
+result = arr.findLast(function(val) {
+  return undefined;
+});
+assert.sameValue(result, undefined, 'coerced undefined');
+
+result = arr.findLast(function(val) {
+  return null;
+});
+assert.sameValue(result, undefined, 'coerced null');
+
+result = arr.findLast(function(val) {
+  return 0;
+});
+assert.sameValue(result, undefined, 'coerced 0');
+
+result = arr.findLast(function(val) {
+  return NaN;
+});
+assert.sameValue(result, undefined, 'coerced NaN');