Add an arbitrary able to generate records

Fixes #40

src/check/arbitrary/RecordArbitrary.ts

@@ -0,0 +1,17 @@
+import Arbitrary from './definition/Arbitrary'
+import MutableRandomGenerator from '../../random/generator/MutableRandomGenerator'
+
+import { generic_tuple } from './TupleArbitrary'
+
+function record<T>(recordModel: {[Key:string]: Arbitrary<T>}): Arbitrary<{[Key:string]: T}> {
+    const keys = Object.keys(recordModel);
+    const arbs: Arbitrary<T>[] = keys.map(v => recordModel[v]);
+    return generic_tuple(arbs).map((gs: T[]) => {
+        const obj: {[Key:string]: T} = {};
+        for (let idx = 0 ; idx != keys.length ; ++idx)
+            obj[keys[idx]] = gs[idx];
+        return obj;
+    });
+}
+
+export { record };

src/fast-check.ts

@@ -18,6 +18,7 @@ import { lorem } from './check/arbitrary/LoremArbitrary'
 import { anything, object, jsonObject, unicodeJsonObject, json, unicodeJson, ObjectConstraints } from './check/arbitrary/ObjectArbitrary'
 import { oneof } from './check/arbitrary/OneOfArbitrary'
 import { option } from './check/arbitrary/OptionArbitrary'
+import { record } from './check/arbitrary/RecordArbitrary'
 import { string, asciiString, string16bits, unicodeString, fullUnicodeString, hexaString, base64String } from './check/arbitrary/StringArbitrary'
 import { set } from './check/arbitrary/SetArbitrary'
 import { tuple, generic_tuple } from './check/arbitrary/TupleArbitrary'
@@ -43,7 +44,7 @@ export {
     integer, nat, // integer types
     char, ascii, char16bits, unicode, fullUnicode, hexa, base64, // single character
     string, asciiString, string16bits, unicodeString, fullUnicodeString, hexaString, base64String, lorem, // strings
-    constant, constantFrom, option, oneof, frequency, array, set, tuple, generic_tuple, // combination of others
+    constant, constantFrom, option, oneof, frequency, array, set, tuple, generic_tuple, record, // combination of others
     anything, object, json, unicodeJson, // complex combinations
     // extend the framework
     Arbitrary, Shrinkable,

test/unit/check/arbitrary/RecordArbitrary.spec.ts

@@ -0,0 +1,27 @@
+import * as assert from 'power-assert';
+import * as fc from '../../../../lib/fast-check';
+
+import { record } from '../../../../src/check/arbitrary/RecordArbitrary';
+import MersenneTwister from '../../../../src/random/generator/MersenneTwister';
+import MutableRandomGenerator from '../../../../src/random/generator/MutableRandomGenerator';
+
+import * as stubArb from '../../stubs/arbitraries';
+import * as stubRng from '../../stubs/generators';
+
+describe("RecordArbitrary", () => {
+    describe('record', () => {
+        it('Should produce a record having the right keys', () => fc.assert(
+            fc.property(fc.array(fc.string()), fc.integer(), (keys, seed) => {
+                const mrng = stubRng.mutable.fastincrease(seed);
+                const expectedRecord = {};
+                const recordModel = {};
+                for (const k of keys) {
+                    expectedRecord[k] = `_${k}_`;
+                    recordModel[k] = stubArb.single(`_${k}_`);
+                }
+                const g = record(recordModel).generate(mrng).value;
+                assert.deepStrictEqual(g, expectedRecord);
+            })
+        ));
+    });
+});