feat(ngMock/$httpBackend): support a matching function for data param

Add support for passing function as validating data:
 - To avoid hacking test method of RegExp
 - Optionally overwrite `toString` method of fn to show validation tips
 - change docs: param description for `when`, `whenPost`, `whenPut`,
   `expect`, `expectPost`, `expectPut`, `expectPATCH`

Closes: #2981

src/ngMock/angular-mocks.js

@@ -1123,7 +1123,8 @@ function createHttpBackendMock($rootScope, $delegate, $browser) {
    *
    * @param {string} method HTTP method.
    * @param {string|RegExp} url HTTP url.
-   * @param {(string|RegExp)=} data HTTP request body.
+   * @param {(string|RegExp|function(string))=} data HTTP request body or function that receives
+   *   data string and returns true if the data is as expected.
    * @param {(Object|function(Object))=} headers HTTP headers or function that receives http header
    *   object and returns true if the headers match the current definition.
    * @returns {requestHandler} Returns an object with `respond` method that control how a matched
@@ -1199,7 +1200,8 @@ function createHttpBackendMock($rootScope, $delegate, $browser) {
    * Creates a new backend definition for POST requests. For more info see `when()`.
    *
    * @param {string|RegExp} url HTTP url.
-   * @param {(string|RegExp)=} data HTTP request body.
+   * @param {(string|RegExp|function(string))=} data HTTP request body or function that receives
+   *   data string and returns true if the data is as expected.
    * @param {(Object|function(Object))=} headers HTTP headers.
    * @returns {requestHandler} Returns an object with `respond` method that control how a matched
    * request is handled.
@@ -1213,7 +1215,8 @@ function createHttpBackendMock($rootScope, $delegate, $browser) {
    * Creates a new backend definition for PUT requests.  For more info see `when()`.
    *
    * @param {string|RegExp} url HTTP url.
-   * @param {(string|RegExp)=} data HTTP request body.
+   * @param {(string|RegExp|function(string))=} data HTTP request body or function that receives
+   *   data string and returns true if the data is as expected.
    * @param {(Object|function(Object))=} headers HTTP headers.
    * @returns {requestHandler} Returns an object with `respond` method that control how a matched
    * request is handled.
@@ -1242,7 +1245,8 @@ function createHttpBackendMock($rootScope, $delegate, $browser) {
    *
    * @param {string} method HTTP method.
    * @param {string|RegExp} url HTTP url.
-   * @param {(string|RegExp)=} data HTTP request body.
+   * @param {(string|RegExp|function(string))=} data HTTP request body or function that receives
+   *   data string and returns true if the data is as expected.
    * @param {(Object|function(Object))=} headers HTTP headers or function that receives http header
    *   object and returns true if the headers match the current expectation.
    * @returns {requestHandler} Returns an object with `respond` method that control how a matched
@@ -1311,7 +1315,8 @@ function createHttpBackendMock($rootScope, $delegate, $browser) {
    * Creates a new request expectation for POST requests. For more info see `expect()`.
    *
    * @param {string|RegExp} url HTTP url.
-   * @param {(string|RegExp)=} data HTTP request body.
+   * @param {(string|RegExp|function(string))=} data HTTP request body or function that receives
+   *   data string and returns true if the data is as expected.
    * @param {Object=} headers HTTP headers.
    * @returns {requestHandler} Returns an object with `respond` method that control how a matched
    *   request is handled.
@@ -1325,7 +1330,8 @@ function createHttpBackendMock($rootScope, $delegate, $browser) {
    * Creates a new request expectation for PUT requests. For more info see `expect()`.
    *
    * @param {string|RegExp} url HTTP url.
-   * @param {(string|RegExp)=} data HTTP request body.
+   * @param {(string|RegExp|function(string))=} data HTTP request body or function that receives
+   *   data string and returns true if the data is as expected.
    * @param {Object=} headers HTTP headers.
    * @returns {requestHandler} Returns an object with `respond` method that control how a matched
    *   request is handled.
@@ -1339,7 +1345,8 @@ function createHttpBackendMock($rootScope, $delegate, $browser) {
    * Creates a new request expectation for PATCH requests. For more info see `expect()`.
    *
    * @param {string|RegExp} url HTTP url.
-   * @param {(string|RegExp)=} data HTTP request body.
+   * @param {(string|RegExp|function(string))=} data HTTP request body or function that receives
+   *   data string and returns true if the data is as expected.
    * @param {Object=} headers HTTP headers.
    * @returns {requestHandler} Returns an object with `respond` method that control how a matched
    *   request is handled.
@@ -1492,6 +1499,7 @@ function MockHttpExpectation(method, url, data, headers) {
   this.matchData = function(d) {
     if (angular.isUndefined(data)) return true;
     if (data && angular.isFunction(data.test)) return data.test(d);
+    if (data && angular.isFunction(data)) return data(d);
     if (data && !angular.isString(data)) return angular.toJson(data) == d;
     return data == d;
   };

test/ngMock/angular-mocksSpec.js

@@ -1037,6 +1037,19 @@ describe('ngMock', function() {
       });
 
 
+      it('should accept data as function', function() {
+        var dataValidator = function(data) {
+          var json = angular.fromJson(data);
+          return !!json.id && json.status === 'N';
+        };
+        var exp = new MockHttpExpectation('POST', '/url', dataValidator);
+
+        expect(exp.matchData({})).toBe(false);
+        expect(exp.match('POST', '/url', '{"id": "xxx", "status": "N"}')).toBe(true);
+        expect(exp.match('POST', '/url', {"id": "xxx", "status": "N"})).toBe(true);
+      });
+
+
       it('should ignore data only if undefined (not null or false)', function() {
         var exp = new MockHttpExpectation('POST', '/url', null);
         expect(exp.matchData(null)).toBe(true);