💥 Include invalid dates by default (#4490)

**💥 Breaking change**

In v3, `fc.date` was not producing "Invalid Date" values by default. One has to specify `noInvalidDate: false` to get some. With this PR we now default the flag to false when not specified: in other words, the new default will be to produce invalid dates except asked explicitly not to.

After that change, if you want not to produce "Invalid Date", you'll have to use:

```js
// in v3, it was only producing valid dates
fc.date()

// equivalent in v4
fc.date({noInvalidDate: true})

//---

// in v3, including invalid dates required users to pass an extra constraint to the arbitrary
fc.date({noInvalidDate: false})

// equivalent in v4
fc.date()
```

You can also prepare yourself to v4 by already toggling: `noInvalidDate: false` on your `fc.date`.

packages/fast-check/src/arbitrary/date.ts

@@ -30,7 +30,7 @@ export interface DateConstraints {
   max?: Date;
   /**
    * When set to true, no more "Invalid Date" can be generated.
-   * @defaultValue true
+   * @defaultValue false
    * @remarks Since 3.13.0
    */
   noInvalidDate?: boolean;
@@ -48,7 +48,7 @@ export function date(constraints: DateConstraints = {}): Arbitrary<Date> {
   // Date min and max in ECMAScript specification : https://stackoverflow.com/a/11526569/3707828
   const intMin = constraints.min !== undefined ? safeGetTime(constraints.min) : -8640000000000000;
   const intMax = constraints.max !== undefined ? safeGetTime(constraints.max) : 8640000000000000;
-  const noInvalidDate = constraints.noInvalidDate === undefined || constraints.noInvalidDate;
+  const noInvalidDate = constraints.noInvalidDate;
   if (safeNumberIsNaN(intMin)) throw new Error('fc.date min must be valid instance of Date');
   if (safeNumberIsNaN(intMax)) throw new Error('fc.date max must be valid instance of Date');
   if (intMin > intMax) throw new Error('fc.date max must be greater or equal to min');

packages/fast-check/test/unit/arbitrary/_internals/mappers/TimeToDate.spec.ts

@@ -10,7 +10,7 @@ import {
 describe('timeToDateUnmapper', () => {
   it('should be able to revert any mapped date correctly even invalid ones', () => {
     fc.assert(
-      fc.property(fc.date({ noInvalidDate: false }), (d) => {
+      fc.property(fc.date(), (d) => {
         // Arrange / Act
         const rev = timeToDateUnmapper(d);
         const revRev = timeToDateMapper(rev);
@@ -22,26 +22,22 @@ describe('timeToDateUnmapper', () => {
   });
 });
 
-describe('timeToDateUnmapperWithNane', () => {
+describe('timeToDateUnmapperWithNaN', () => {
   it('should be able to revert any mapped date correctly even invalid once', () => {
     fc.assert(
-      fc.property(
-        fc.date({ noInvalidDate: false }),
-        fc.integer({ min: -8640000000000000, max: 8640000000000001 }),
-        (d, nanValue) => {
-          // Arrange / Act
-          const rev = timeToDateUnmapperWithNaN(nanValue)(d);
-          const revRev = timeToDateMapperWithNaN(nanValue)(rev);
+      fc.property(fc.date(), fc.integer({ min: -8640000000000000, max: 8640000000000001 }), (d, nanValue) => {
+        // Arrange / Act
+        const rev = timeToDateUnmapperWithNaN(nanValue)(d);
+        const revRev = timeToDateMapperWithNaN(nanValue)(rev);
 
-          // Assert
-          if (d.getTime() === nanValue) {
-            expect(rev).toBe(nanValue);
-            expect(revRev.getTime()).toEqual(Number.NaN);
-          } else {
-            expect(revRev.getTime()).toEqual(d.getTime());
-          }
-        },
-      ),
+        // Assert
+        if (d.getTime() === nanValue) {
+          expect(rev).toBe(nanValue);
+          expect(revRev.getTime()).toEqual(Number.NaN);
+        } else {
+          expect(revRev.getTime()).toEqual(d.getTime());
+        }
+      }),
     );
   });
 });

packages/fast-check/test/unit/arbitrary/date.spec.ts

@@ -71,7 +71,7 @@ describe('date', () => {
     fc.assert(
       fc.property(constraintsArb(), (constraints) => {
         // Arrange
-        const withInvalidDates = constraints.noInvalidDate === false;
+        const withInvalidDates = !constraints.noInvalidDate;
         const { instance, map } = fakeArbitrary<number>();
         const { instance: mappedInstance } = fakeArbitrary<Date>();
         const integer = vi.spyOn(IntegerMock, 'integer');
@@ -115,7 +115,7 @@ describe('date', () => {
         const d = mapper(rangeMin! + (mod % (rangeMax! - rangeMin! + 1))) as Date;
 
         // Assert
-        if (constraints.noInvalidDate !== false || !Number.isNaN(d.getTime())) {
+        if (constraints.noInvalidDate || !Number.isNaN(d.getTime())) {
           expect(d.getTime()).not.toBe(Number.NaN);
           if (constraints.min) expect(d.getTime()).toBeGreaterThanOrEqual(constraints.min.getTime());
           if (constraints.max) expect(d.getTime()).toBeLessThanOrEqual(constraints.max.getTime());
@@ -153,7 +153,7 @@ describe('date (integration)', () => {
   const extraParameters: fc.Arbitrary<Extra> = constraintsArb();
 
   const isCorrect = (d: Date, extra: Extra) => {
-    if (extra.noInvalidDate || extra.noInvalidDate === undefined) {
+    if (extra.noInvalidDate) {
       expect(d.getTime()).not.toBe(Number.NaN);
     } else if (Number.isNaN(d.getTime())) {
       return;
@@ -203,7 +203,13 @@ describe('date (integration)', () => {
 
 function constraintsArb() {
   return fc
-    .tuple(fc.date(), fc.date(), fc.boolean(), fc.boolean(), fc.option(fc.boolean(), { nil: undefined }))
+    .tuple(
+      fc.date({ noInvalidDate: true }),
+      fc.date({ noInvalidDate: true }),
+      fc.boolean(),
+      fc.boolean(),
+      fc.option(fc.boolean(), { nil: undefined }),
+    )
     .map(([d1, d2, withMin, withMax, noInvalidDate]) => {
       const min = d1 < d2 ? d1 : d2;
       const max = d1 < d2 ? d2 : d1;
@@ -213,7 +219,11 @@ function constraintsArb() {
 
 function invalidRangeConstraintsArb() {
   return fc
-    .tuple(fc.date(), fc.date(), fc.option(fc.boolean(), { nil: undefined }))
+    .tuple(
+      fc.date({ noInvalidDate: true }),
+      fc.date({ noInvalidDate: true }),
+      fc.option(fc.boolean(), { nil: undefined }),
+    )
     .filter(([d1, d2]) => +d1 !== +d2)
     .map(([d1, d2, noInvalidDate]) => {
       const min = d1 < d2 ? d1 : d2;

website/docs/core-blocks/arbitraries/composites/object.md

@@ -129,11 +129,11 @@ fc.record(
 );
 // Note: All keys except 'id' will be optional values. id has been marked as required.
 // Examples of generated values:
-// • {"id":"46045be9-0009-4000-8000-0008ffffffed","name":"Karen","age":11,"birthday":new Date("2100-12-31T23:59:59.996Z")}
+// • {"id":"46045be9-0009-4000-8000-0008ffffffed","name":"Karen","age":11,"birthday":new Date("2100-12-31T23:59:59.997Z")}
 // • {"id":"fffffffe-0015-4000-95a0-f8e9ffffffe7","name":"Karen","birthday":new Date("1970-01-01T00:00:00.018Z")}
 // • {"id":"e2b066ec-000b-4000-bfff-ffe7ccb1828d","name":"Karen","age":17}
 // • {"id":"43b7d8e5-d043-42ef-8000-001a00000005","age":16,"birthday":new Date("2004-10-16T22:01:09.416Z")}
-// • {"id":"00000007-2008-452e-8000-00133ed36be7","name":"Karen","age":6,"birthday":new Date("2100-12-31T23:59:59.981Z")}
+// • {"id":"00000007-2008-452e-8000-00133ed36be7","name":"Karen","age":6,"birthday":new Date("2100-12-31T23:59:59.982Z")}
 // • …
 
 fc.record(

website/docs/core-blocks/arbitraries/primitives/date.md

@@ -21,7 +21,7 @@ Generate any possible dates in the specified range. Both the lower bound and upp
 
 - `min?` — default: `new Date(-8640000000000000)` — _lower bound of the range (included)_
 - `max?` — default: `new Date(8640000000000000)` — _upper bound of the range (included)_
-- `noInvalidDate?` — default: `true` — _when `true` the Date "Invalid Date" will never be defined_
+- `noInvalidDate?` — default: `false` — _when `true` the Date "Invalid Date" will never be defined_
 
 **Usages:**
 
@@ -41,7 +41,7 @@ fc.date({ min: new Date('2000-01-01T00:00:00.000Z') });
 // • new Date("2000-01-01T00:00:00.039Z")
 // • new Date("2000-01-01T00:00:00.047Z")
 // • new Date("2000-01-01T00:00:00.003Z")
-// • new Date("+275760-09-12T23:59:59.981Z")
+// • new Date("+275760-09-12T23:59:59.982Z")
 // • …
 
 fc.date({ max: new Date('2000-01-01T00:00:00.000Z') });
@@ -58,9 +58,18 @@ fc.date({ min: new Date('2000-01-01T00:00:00.000Z'), max: new Date('2000-12-31T2
 // • new Date("2000-05-15T03:02:40.263Z")
 // • new Date("2000-10-22T03:00:45.936Z")
 // • new Date("2000-02-25T19:00:10.679Z")
-// • new Date("2000-12-31T23:59:59.996Z")
+// • new Date("2000-12-31T23:59:59.997Z")
 // • new Date("2000-01-04T14:12:03.484Z")
 // • …
+
+fc.date({ noInvalidDate: true });
+// Examples of generated values:
+// • new Date("-043663-07-08T11:17:34.486Z")
+// • new Date("-169183-12-11T00:28:46.358Z")
+// • new Date("1969-12-31T23:59:59.988Z")
+// • new Date("1969-12-31T23:59:59.984Z")
+// • new Date("-271821-04-20T00:00:00.033Z")
+// • …
 ```
 
 Resources: [API reference](https://fast-check.dev/api-reference/functions/date.html).