honour Date object passed as legacy 2nd arg to isAfter / isBefore

src/lib/isAfter.js

@@ -1,11 +1,23 @@
 import toDate from './toDate';
 
+function resolveComparisonDate(options) {
+  if (options instanceof Date) {
+    return options;
+  }
+  if (typeof options === 'object' && options !== null) {
+    return options.comparisonDate;
+  }
+  return options;
+}
+
 export default function isAfter(date, options) {
   // For backwards compatibility:
   // isAfter(str [, date]), i.e. `options` could be used as argument for the legacy `date`
-  const comparisonDate = (typeof options === 'object' ? options.comparisonDate : options) || Date().toString();
+  const comparisonDate = resolveComparisonDate(options) || Date().toString();
 
-  const comparison = toDate(comparisonDate);
+  const comparison = comparisonDate instanceof Date
+    ? comparisonDate
+    : toDate(comparisonDate);
   const original = toDate(date);
 
   return !!(original && comparison && original > comparison);

src/lib/isBefore.js

@@ -1,11 +1,23 @@
 import toDate from './toDate';
 
+function resolveComparisonDate(options) {
+  if (options instanceof Date) {
+    return options;
+  }
+  if (typeof options === 'object' && options !== null) {
+    return options.comparisonDate;
+  }
+  return options;
+}
+
 export default function isBefore(date, options) {
   // For backwards compatibility:
   // isBefore(str [, date]), i.e. `options` could be used as argument for the legacy `date`
-  const comparisonDate = (typeof options === 'object' ? options.comparisonDate : options) || Date().toString();
+  const comparisonDate = resolveComparisonDate(options) || Date().toString();
 
-  const comparison = toDate(comparisonDate);
+  const comparison = comparisonDate instanceof Date
+    ? comparisonDate
+    : toDate(comparisonDate);
   const original = toDate(date);
 
   return !!(original && comparison && original < comparison);

test/validators/isAfter.test.js

@@ -74,3 +74,22 @@ describe('isAfter', () => {
     });
   });
 });
+describe('(legacy syntax with Date object)', () => {
+  it('should accept a Date object as the second argument and use it as the comparison date', () => {
+    // Regression: previously `typeof options === 'object' && options.comparisonDate === undefined`
+    // meant the Date argument was silently ignored and the comparison fell back to "now".
+    test({
+      validator: 'isAfter',
+      args: [new Date('2010-01-01T00:00:00Z')],
+      valid: ['2010-01-02', '2011-08-04', '2030-01-01', new Date(2020, 0, 1).toString()],
+      invalid: ['2009-12-31', '2010-01-01', new Date(0).toString()],
+    });
+
+    test({
+      validator: 'isAfter',
+      args: [new Date('2030-01-01T00:00:00Z')],
+      valid: ['2030-01-02', '2050-06-15'],
+      invalid: ['2025-06-26', '2029-12-31', new Date(2025, 0, 1).toString()],
+    });
+  });
+});

test/validators/isBefore.test.js

@@ -117,3 +117,22 @@ describe('isBefore', () => {
     });
   });
 });
+describe('legacy syntax with Date object', () => {
+  it('should accept a Date object as the second argument and use it as the comparison date', () => {
+    // Regression: previously `typeof options === 'object' && options.comparisonDate === undefined`
+    // meant the Date argument was silently ignored and the comparison fell back to "now".
+    test({
+      validator: 'isBefore',
+      args: [new Date('2010-01-01T00:00:00Z')],
+      valid: ['2009-12-31', '1999-12-31', new Date(0).toString()],
+      invalid: ['2010-01-02', '2011-08-04', '2030-01-01'],
+    });
+
+    test({
+      validator: 'isBefore',
+      args: [new Date('2030-01-01T00:00:00Z')],
+      valid: ['2025-06-26', '2029-12-31', new Date(2025, 0, 1).toString()],
+      invalid: ['2030-01-02', '2050-06-15'],
+    });
+  });
+});