Adding tests for transformers

test/specs/transform.spec.js

+describe('transform', function () {
+  beforeEach(function () {
+    jasmine.Ajax.install();
+  });
+
+  it('should transform JSON to string', function () {
+    var data = {
+      foo: 'bar'
+    };
+
+    axios({
+      url: '/foo',
+      method: 'post',
+      data: data
+    });
+
+    var request = jasmine.Ajax.requests.mostRecent();
+    expect(request.params).toEqual('{"foo":"bar"}');
+  });
+
+  it('should override default transform', function () {
+    var data = {
+      foo: 'bar'
+    };
+
+    axios({
+      url: '/foo',
+      method: 'post',
+      data: data,
+      transformRequest: function (data) {
+        return data;
+      }
+    });
+
+    var request = jasmine.Ajax.requests.mostRecent();
+    expect(typeof request.params).toEqual('object');
+  });
+
+  it('should allow an Array of transformers', function () {
+    var data = {
+      foo: 'bar'
+    };
+
+    axios({
+      url: '/foo',
+      method: 'post',
+      data: data,
+      transformRequest: axios.defaults.transformRequest.concat(
+        function (data) {
+          return data.replace('bar', 'baz');
+        }
+      )
+    });
+
+    var request = jasmine.Ajax.requests.mostRecent();
+    expect(request.params).toEqual('{"foo":"baz"}');
+  });
+
+  it('should allowing mutating headers', function () {
+    var token = Math.floor(Math.random() * Math.pow(2, 64)).toString(36);
+
+    axios({
+      url: '/foo',
+      transformRequest: function (data, headers) {
+        headers['X-Authorization'] = token;
+      }
+    });
+
+    var request = jasmine.Ajax.requests.mostRecent();
+    expect(request.requestHeaders['X-Authorization']).toEqual(token);
+  });
+});
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