intl: rework Intl.NumberFormat.prototype.formatToParts tests

Rework the available tests for Intl.NumberFormat.prototype.formatToParts
to improve consistency and readability.

test/intl402/NumberFormat/prototype/formatToParts/formatToParts.js

@@ -1,17 +0,0 @@
-// Copyright 2016 Mozilla Corporation. All rights reserved.
-// This code is governed by the license found in the LICENSE file.
-
-/*---
-description: Property type and descriptor. 
-includes: [propertyHelper.js]
----*/
-
-assert.sameValue(
-  typeof Intl.NumberFormat.prototype.formatToParts,
-  'function',
-  '`typeof Intl.NumberFormat.prototype.formatToParts` is `function`'
-);
-
-verifyNotEnumerable(Intl.NumberFormat.prototype, 'formatToParts');
-verifyWritable(Intl.NumberFormat.prototype, 'formatToParts');
-verifyConfigurable(Intl.NumberFormat.prototype, 'formatToParts');

test/intl402/NumberFormat/prototype/formatToParts/prop-desc.js

@@ -0,0 +1,37 @@
+// Copyright 2016 Mozilla Corporation. All rights reserved.
+// This code is governed by the license found in the LICENSE file.
+
+/*---
+esid: sec-intl.numberformat.prototype.formattoparts
+description: >
+  "formatToParts" property of Intl.NumberFormat.prototype.
+info: |
+  11.4.4 Intl.NumberFormat.prototype.formatToParts
+
+  7 Requirements for Standard Built-in ECMAScript Objects
+
+    Unless specified otherwise in this document, the objects, functions, and constructors
+    described in this standard are subject to the generic requirements and restrictions
+    specified for standard built-in ECMAScript objects in the ECMAScript 2018 Language
+    Specification, 9th edition, clause 17, or successor.
+
+  17 ECMAScript Standard Built-in Objects:
+
+    Every accessor property described in clauses 18 through 26 and in Annex B.2 has the
+    attributes { [[Enumerable]]: false, [[Configurable]]: true } unless otherwise specified.
+    If only a get accessor function is described, the set accessor function is the default
+    value, undefined. If only a set accessor is described the get accessor is the default
+    value, undefined.
+
+includes: [propertyHelper.js]
+---*/
+
+assert.sameValue(
+  typeof Intl.NumberFormat.prototype.formatToParts,
+  'function',
+  '`typeof Intl.NumberFormat.prototype.formatToParts` is `function`'
+);
+
+verifyNotEnumerable(Intl.NumberFormat.prototype, 'formatToParts');
+verifyWritable(Intl.NumberFormat.prototype, 'formatToParts');
+verifyConfigurable(Intl.NumberFormat.prototype, 'formatToParts');

test/intl402/NumberFormat/prototype/formatToParts/return-abrupt-tonumber.js

@@ -1,40 +0,0 @@
-// Copyright 2016 Mozilla Corporation. All rights reserved.
-// This code is governed by the license found in the LICENSE file.
-//
-/*---
-description: >
-  Return abrupt completions from ToNumber(date)
-info: |
-  Intl.NumberFormat.prototype.formatToParts ([ value ])
-
-  5. Let _x_ be ? ToNumber(_value_).
-features: [Symbol]
----*/
-
-var obj1 = {
-  valueOf: function() {
-    throw new Test262Error();
-  }
-};
-
-var obj2 = {
-  toString: function() {
-    throw new Test262Error();
-  }
-};
-
-var nf = new Intl.NumberFormat(["pt-BR"]);
-
-assert.throws(Test262Error, function() {
-  nf.formatToParts(obj1);
-}, "valueOf");
-
-assert.throws(Test262Error, function() {
-  nf.formatToParts(obj2);
-}, "toString");
-
-var s = Symbol('1');
-assert.throws(TypeError, function() {
-  nf.formatToParts(s);
-}, "symbol");
-

test/intl402/NumberFormat/prototype/formatToParts/value-tonumber.js

@@ -0,0 +1,42 @@
+// Copyright 2016 Mozilla Corporation. All rights reserved.
+// This code is governed by the license found in the LICENSE file.
+
+/*---
+esid: sec-intl.numberformat.prototype.formattoparts
+description: >
+  Tests that Intl.NumberFormat.prototype.formatToParts converts
+  its argument (called value) to a number using ToNumber (7.1.3).
+info: |
+  11.1.4 Number Format Functions
+
+  4. Let x be ? ToNumber(value).
+features: [Symbol]
+---*/
+
+const toNumberResults = [
+  [undefined, NaN],
+  [null, +0],
+  [true, 1],
+  [false, 0],
+  ['42', 42],
+  ['foo', NaN]
+];
+
+const nf = new Intl.NumberFormat();
+
+toNumberResults.forEach(pair => {
+  const [value, result] = pair;
+  assert.sameValue(nf.formatToParts(value), nf.formatToParts(result));
+});
+
+let count = 0;
+const dummy = {};
+dummy[Symbol.toPrimitive] = hint => (hint === 'number' ? ++count : NaN);
+assert.sameValue(nf.formatToParts(dummy), nf.formatToParts(count));
+assert.sameValue(count, 1);
+
+assert.throws(
+  TypeError,
+  () => nf.formatToParts(Symbol()),
+  "ToNumber(arg) throws a TypeError when arg is of type 'Symbol'"
+);