Document use of Number.MAX_SAFE_INTEGER

Fixes #98 Fixes #99
dubzzz · May 21, 2018 · b45b90e · b45b90e
1 parent d752e66
commit b45b90e
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Showing 2 changed files with 14 additions and 3 deletions.
diff --git a/src/check/arbitrary/IntegerArbitrary.ts b/src/check/arbitrary/IntegerArbitrary.ts
@@ -78,13 +78,14 @@ class IntegerArbitrary extends ArbitraryWithShrink<number> {
 function integer(): ArbitraryWithShrink<number>;
 /**
  * For integers between -2147483648 (included) and max (included)
- * @param max Upper bound for the generated integers
+ * @param max Upper bound for the generated integers (eg.: 2147483647, Number.MAX_SAFE_INTEGER)
  */
 function integer(max: number): ArbitraryWithShrink<number>;
 /**
  * For integers between min (included) and max (included)
- * @param min Lower bound for the generated integers
- * @param max Upper bound for the generated integers
+ *
+ * @param min Lower bound for the generated integers (eg.: 0, Number.MIN_SAFE_INTEGER)
+ * @param max Upper bound for the generated integers (eg.: 2147483647, Number.MAX_SAFE_INTEGER)
  */
 function integer(min: number, max: number): ArbitraryWithShrink<number>;
 function integer(a?: number, b?: number): ArbitraryWithShrink<number> {

diff --git a/test/e2e/arbitraries/IntegerArbitrary.spec.ts b/test/e2e/arbitraries/IntegerArbitrary.spec.ts
@@ -24,5 +24,15 @@ describe(`IntegerArbitrary (seed: ${seed})`, () => {
       assert.ok(out.failed, 'Should have failed');
       assert.deepEqual(out.counterexample, [100], 'Should shrink to counterexample 100');
     });
+    it('Should detect overflow', () => {
+      const out = fc.check(
+        fc.property(
+          fc.nat(Number.MAX_SAFE_INTEGER),
+          fc.nat(Number.MAX_SAFE_INTEGER),
+          (a: number, b: number) => a + b !== a + b + 1
+        )
+      );
+      assert.ok(out.failed, 'Should have failed');
+    });
   });
 });