Adding stringOf Arbitrary

dubzzz · May 6, 2018 · cc73ab3 · cc73ab3
1 parent 0dd1e66
commit cc73ab3
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Showing 3 changed files with 62 additions and 1 deletion.
diff --git a/src/check/arbitrary/StringArbitrary.ts b/src/check/arbitrary/StringArbitrary.ts
@@ -31,6 +31,25 @@ function Base64StringArbitrary(minLength: number, maxLength: number) {
   });
 }
 
+/**
+ * Arbitrary producing string using the characters produced by `charArb`
+ */
+function stringOf(charArb: Arbitrary<string>): Arbitrary<string>;
+/**
+ * Arbitrary producing string using the characters produced by `charArb`
+ * @param maxLength Upper bound of the generated string length
+ */
+function stringOf(charArb: Arbitrary<string>, maxLength: number): Arbitrary<string>;
+/**
+ * Arbitrary producing string using the characters produced by `charArb`
+ * @param minLength Lower bound of the generated string length
+ * @param maxLength Upper bound of the generated string length
+ */
+function stringOf(charArb: Arbitrary<string>, minLength: number, maxLength: number): Arbitrary<string>;
+function stringOf(charArb: Arbitrary<string>, aLength?: number, bLength?: number): Arbitrary<string> {
+  return StringArbitrary(charArb, aLength, bLength);
+}
+
 /**
  * Arbitrary producing string of {@link char}
  */
@@ -171,4 +190,4 @@ function base64String(aLength?: number, bLength?: number): Arbitrary<string> {
   return Base64StringArbitrary(minLength + 3 - (minLength + 3) % 4, maxLength - maxLength % 4); // base64 length is always a multiple of 4
 }
 
-export { string, asciiString, string16bits, unicodeString, fullUnicodeString, hexaString, base64String };
+export { stringOf, string, asciiString, string16bits, unicodeString, fullUnicodeString, hexaString, base64String };
diff --git a/src/fast-check-default.ts b/src/fast-check-default.ts
@@ -37,6 +37,7 @@ import {
   hexaString,
   string,
   string16bits,
+  stringOf,
   unicodeString
 } from './check/arbitrary/StringArbitrary';
 import { genericTuple, tuple } from './check/arbitrary/TupleArbitrary';

diff --git a/test/unit/check/arbitrary/StringArbitrary.spec.ts b/test/unit/check/arbitrary/StringArbitrary.spec.ts
@@ -1,7 +1,9 @@
 import * as assert from 'assert';
 import * as fc from '../../../../lib/fast-check';
 
+import { constantFrom } from '../../../../src/check/arbitrary/ConstantArbitrary';
 import {
+  stringOf,
   string,
   asciiString,
   string16bits,
@@ -10,13 +12,52 @@ import {
   base64String
 } from '../../../../src/check/arbitrary/StringArbitrary';
 
+import * as genericHelper from './generic/GenericArbitraryHelper';
+
 import * as stubRng from '../../stubs/generators';
 
 const minMax = fc
   .tuple(fc.integer(0, 10000), fc.integer(0, 10000))
   .map(t => (t[0] < t[1] ? { min: t[0], max: t[1] } : { min: t[1], max: t[0] }));
 
 describe('StringArbitrary', () => {
+  describe('stringOf', () => {
+    describe('Given no length constraints', () => {
+      genericHelper.isValidArbitrary(() => stringOf(constantFrom('\u{1f431}', 'D', '1').noShrink()), {
+        isStrictlySmallerValue: (g1, g2) => [...g1].length < [...g2].length,
+        isValidValue: (g: string) =>
+          typeof g === 'string' && [...g].every(c => c === '\u{1f431}' || c === 'D' || c === '1')
+      });
+    });
+    describe('Given maximal length only', () => {
+      genericHelper.isValidArbitrary(
+        (maxLength: number) => stringOf(constantFrom('\u{1f431}', 'D', '1').noShrink(), maxLength),
+        {
+          seedGenerator: fc.nat(100),
+          isStrictlySmallerValue: (g1, g2) => [...g1].length < [...g2].length,
+          isValidValue: (g: string, maxLength: number) =>
+            typeof g === 'string' &&
+            [...g].length <= maxLength &&
+            [...g].every(c => c === '\u{1f431}' || c === 'D' || c === '1')
+        }
+      );
+    });
+    describe('Given minimal and maximal lengths', () => {
+      genericHelper.isValidArbitrary(
+        (constraints: { min: number; max: number }) =>
+          stringOf(constantFrom('\u{1f431}', 'D', '1').noShrink(), constraints.min, constraints.max),
+        {
+          seedGenerator: genericHelper.minMax(fc.nat(100)),
+          isStrictlySmallerValue: (g1, g2) => [...g1].length < [...g2].length,
+          isValidValue: (g: string, constraints: { min: number; max: number }) =>
+            typeof g === 'string' &&
+            [...g].length >= constraints.min &&
+            [...g].length <= constraints.max &&
+            [...g].every(c => c === '\u{1f431}' || c === 'D' || c === '1')
+        }
+      );
+    });
+  });
   describe('string', () => {
     it('Should generate printable characters', () =>
       fc.assert(