Fix issue #2634 moving the conditional check for filtering

extensions/applicationinsights-dependencies-js/Tests/Unit/src/ajax.tests.ts

@@ -1909,6 +1909,51 @@ export class AjaxTests extends AITestClass {
             }
         });
 
+        this.testCase({
+            name: "Fetch: fetch keeps custom headers when correlation headers are discarded by dependencyListeners",
+            test: () => {
+                hookFetch((resolve) => {
+                    AITestClass.orgSetTimeout(function() {
+                        resolve();
+                    }, 0);
+                });
+
+
+                this._ajax = new AjaxMonitor();
+                this._ajax.addDependencyListener((details: IDependencyListenerDetails) => {
+                    return false;
+                });
+                let appInsightsCore = new AppInsightsCore();
+                let coreConfig = {
+                    instrumentationKey: "",
+                    disableFetchTracking: false,
+                    disableAjaxTracking: true
+                };
+                appInsightsCore.initialize(coreConfig, [this._ajax, new TestChannelPlugin()]);
+                let fetchSpy = this.sandbox.spy(window, "fetch");
+
+                // Setup
+                let headers = new Headers();
+                headers.append('My-Header', 'Header field');
+                let init = {
+                    method: 'get',
+                    headers: headers
+                };
+                const url = 'https://httpbin.org/status/200';
+
+                let headerSpy = this.sandbox.spy(this._ajax, "includeCorrelationHeaders");
+
+                // Act
+                Assert.ok(fetchSpy.notCalled);
+                fetch(url, init);
+
+                // Assert
+                Assert.ok(fetchSpy.calledOnce);
+                Assert.ok(headerSpy.calledOnce);
+                Assert.deepEqual(init, headerSpy.returnValue || headerSpy.returnValues[0]);
+            }
+        });
+
         this.testCaseAsync({
             name: "Fetch: should create and pass a traceparent header if ai and w3c is enabled with custom headers",
             stepDelay: 10,

extensions/applicationinsights-dependencies-js/src/ajax.ts

@@ -466,8 +466,6 @@ export class AjaxMonitor extends BaseTelemetryPlugin implements IAjaxMonitorPlug
 
                             init.headers = headers;
                         }
-
-                        return init;
                     } else if (xhr) { // XHR
                         if (correlationIdCanIncludeCorrelationHeader(_extensionConfig, ajaxData.getAbsoluteUrl(), currentWindowHost)) {
                             if (_isUsingAIHeaders) {
@@ -512,12 +510,10 @@ export class AjaxMonitor extends BaseTelemetryPlugin implements IAjaxMonitorPlug
                                 }
                             }
                         }
-
-                        return xhr;
                     }
                 }
 
-                return undefined;
+                return xhr || init;
             }
 
             _self.trackDependencyDataInternal = (dependency: IDependencyTelemetry, properties?: { [key: string]: any }, systemProperties?: { [key: string]: any }) => {