Date validator enhancement: before/after/onOrBefore/onOrAfter accept a function that returns a date

README.md

@@ -197,14 +197,15 @@ Validates the length of a `String` or an `Array`.
 
 #### `date`
 
-This API accepts valid Date objects or a Date in milliseconds since Jan 1 1970.  Strings are currently not supported.  It is recommended you use use native JavaScript or you library of choice to generate a date from your data.
+This API accepts valid Date objects or a Date in milliseconds since Jan 1 1970, or a functiom that returns a Date.  Strings are currently not supported.  It is recommended you use use native JavaScript or you library of choice to generate a date from your data.
 
 ```js
 {
   propertyName: validateDate({ before: new Date('3000-01-01') }), // must be before 1st Jan. 3000
   propertyName: validateDate({ onOrBefore: Date.parse(new Date('3000-01-01')) }), // must be not after 1st Jan. 3000
   propertyName: validateDate({ after: new Date('3000-01-01') }), // must be after 1st Jan. 3000
   propertyName: validateDate({ onOrAfter: new Date('3000-01-01') }), // must be not before 1st Jan. 3000
+  propertyName: validateDate({ onOrAfter: () => new Date() }), // must not be in the past
   propertyName: validateDate({ onOrAfter: '3000-01-01' }), // Error
 }
 ```

addon/utils/to-date.js

@@ -7,6 +7,10 @@
 export default function toDate(argument) {
   const argStr = Object.prototype.toString.call(argument)
 
+  if (typeof argument === "function") {
+    argument = argument()
+  }
+
   if (
     argument instanceof Date ||
     (typeof argument === 'object' && argStr === '[object Date]')

tests/unit/validators/date-test.js

@@ -119,6 +119,14 @@ module('Unit | Validator | date', function() {
       'date is after "before" date'
     );
 
+    options = { before: () => startDate };
+    validator = validateDate(options);
+    assert.equal(
+      validator(key, afterDate),
+      buildMessage(key, { afterDate, message: `[BEFORE] date is NOT before ${afterDate}` }),
+      'before accepts a function that returns a date'
+    );
+
     options = { before: afterDate };
     validator = validateDate(options);
     assert.equal(
@@ -145,6 +153,14 @@ module('Unit | Validator | date', function() {
       'date is after "onOrBefore" date'
     );
 
+    options = { onOrBefore: () => startDate };
+    validator = validateDate(options);
+    assert.equal(
+      validator(key, afterDate),
+      buildMessage(key, { afterDate, message: `[ON OR BEFORE] date is NOT on or before ${afterDate}` }),
+      'onOrBefore accepts a function that returns a date'
+    );
+
     options = { onOrBefore: afterDate };
     validator = validateDate(options);
     assert.equal(
@@ -171,6 +187,14 @@ module('Unit | Validator | date', function() {
       'date is after the "after" date'
     );
 
+    options = { after: () => afterDate };
+    validator = validateDate(options);
+    assert.equal(
+      validator(key, startDate),
+      buildMessage(key, { startDate, message: `[AFTER] date is NOT after ${startDate}` }),
+      "after accepts a function that returns a date"
+    );
+
     options = { after: startDate };
     validator = validateDate(options);
     assert.equal(
@@ -197,6 +221,14 @@ module('Unit | Validator | date', function() {
       'date onOrAfter the "onOrAfter" date is not allowed'
     );
 
+    options = { onOrAfter: () => onOrAfterDate };
+    validator = validateDate(options);
+    assert.equal(
+      validator(key, startDate),
+      buildMessage(key, { onOrAfterDate, message: `[ON OR AFTER] date is NOT on or after ${startDate}` }),
+      'onOrAfter accepts a function that returns a date'
+    );
+
     options = { onOrAfter: startDate };
     validator = validateDate(options);
     assert.equal(