fix(date): ensures correct range for birthdate (#2535)

3 files changed, 36 insertions, 7 deletions

diff --git a/src/modules/date/index.ts b/src/modules/date/index.ts
index 69854688..d79da51f 100644
--- a/src/modules/date/index.ts
+++ b/src/modules/date/index.ts
@@ -890,7 +890,7 @@ export class SimpleDateModule extends SimpleModuleBase {
         options.min ?? refYear - 80
       );
       max = new Date(Date.UTC(0, 11, 30)).setUTCFullYear(
-        options.max ?? refYear - 18
+        options.max ?? refYear - 19
       );
     }
 
diff --git a/test/modules/__snapshots__/date.spec.ts.snap b/test/modules/__snapshots__/date.spec.ts.snap
index 701c8cc7..4ade2cc7 100644
--- a/test/modules/__snapshots__/date.spec.ts.snap
+++ b/test/modules/__snapshots__/date.spec.ts.snap
@@ -71,11 +71,11 @@ exports[`date > 42 > birthdate > with age mode and refDate 1`] = `1963-09-27T06:
 
 exports[`date > 42 > birthdate > with age range and refDate 1`] = `1962-12-27T20:13:59.702Z`;
 
-exports[`date > 42 > birthdate > with only refDate 1`] = `1964-08-06T01:03:57.017Z`;
+exports[`date > 42 > birthdate > with only refDate 1`] = `1964-03-22T08:05:39.972Z`;
 
 exports[`date > 42 > birthdate > with year and refDate 1`] = `0020-07-07T19:06:53.022Z`;
 
-exports[`date > 42 > birthdate > with year mode and refDate 1`] = `1964-08-06T01:03:57.017Z`;
+exports[`date > 42 > birthdate > with year mode and refDate 1`] = `1964-03-22T08:05:39.972Z`;
 
 exports[`date > 42 > birthdate > with year range and refDate 1`] = `0057-12-20T11:59:23.890Z`;
 
@@ -199,11 +199,11 @@ exports[`date > 1211 > birthdate > with age mode and refDate 1`] = `1998-08-21T2
 
 exports[`date > 1211 > birthdate > with age range and refDate 1`] = `1996-10-13T01:44:07.645Z`;
 
-exports[`date > 1211 > birthdate > with only refDate 1`] = `1999-06-29T11:06:58.506Z`;
+exports[`date > 1211 > birthdate > with only refDate 1`] = `1998-07-25T13:16:46.938Z`;
 
 exports[`date > 1211 > birthdate > with year and refDate 1`] = `0021-01-26T13:16:31.421Z`;
 
-exports[`date > 1211 > birthdate > with year mode and refDate 1`] = `1999-06-29T11:06:58.506Z`;
+exports[`date > 1211 > birthdate > with year mode and refDate 1`] = `1998-07-25T13:16:46.938Z`;
 
 exports[`date > 1211 > birthdate > with year range and refDate 1`] = `0113-12-03T19:45:27.654Z`;
 
@@ -325,11 +325,11 @@ exports[`date > 1337 > birthdate > with age mode and refDate 1`] = `1956-08-25T0
 
 exports[`date > 1337 > birthdate > with age range and refDate 1`] = `1956-02-15T21:16:40.120Z`;
 
-exports[`date > 1337 > birthdate > with only refDate 1`] = `1957-07-05T09:38:29.057Z`;
+exports[`date > 1337 > birthdate > with only refDate 1`] = `1957-03-31T18:18:18.869Z`;
 
 exports[`date > 1337 > birthdate > with year and refDate 1`] = `0020-05-27T14:46:44.831Z`;
 
-exports[`date > 1337 > birthdate > with year mode and refDate 1`] = `1957-07-05T09:38:29.057Z`;
+exports[`date > 1337 > birthdate > with year mode and refDate 1`] = `1957-03-31T18:18:18.869Z`;
 
 exports[`date > 1337 > birthdate > with year range and refDate 1`] = `0046-08-09T19:19:18.047Z`;
 
diff --git a/test/modules/date.spec.ts b/test/modules/date.spec.ts
index 715d714a..bbd8020d 100644
--- a/test/modules/date.spec.ts
+++ b/test/modules/date.spec.ts
@@ -587,6 +587,35 @@ describe('date', () => {
           expect(birthdate.getUTCFullYear()).toBeLessThanOrEqual(max);
         });
 
+        it('returns a random birthdate that is 18+ by default', () => {
+          // Generate the latest possible value => youngest
+          faker.seed(2855577693);
+
+          const refDate = new Date();
+          const birthdate = faker.date.birthdate({ refDate });
+          expect(birthdate).toBeInstanceOf(Date);
+          const value = birthdate.valueOf();
+          const refDateValue = refDate.valueOf();
+          expect(value).toBeLessThanOrEqual(refDateValue);
+          const deltaDate = new Date(refDateValue - value);
+          expect(deltaDate.getUTCFullYear() - 1970).toBeGreaterThanOrEqual(18);
+        });
+
+        it('returns a random birthdate in one year', () => {
+          const min = 1990;
+          const max = 1990;
+
+          const birthdate = faker.date.birthdate({ min, max, mode: 'year' });
+
+          // birthdate is a date object
+          expect(birthdate).toBeInstanceOf(Date);
+          expect(birthdate.toISOString()).not.toMatch(/T00:00:00.000Z/);
+
+          // Generated date is between min and max
+          expect(birthdate.getUTCFullYear()).toBeGreaterThanOrEqual(min);
+          expect(birthdate.getUTCFullYear()).toBeLessThanOrEqual(max);
+        });
+
         it('returns a random birthdate between two ages', () => {
           const min = 4;
           const max = 5;