feat: Add basic logging support for browser-telemetry.

packages/telemetry/browser-telemetry/__tests__/BrowserTelemetryImpl.test.ts

@@ -1,3 +1,4 @@
+import { LDClientLogging } from '../src/api';
 import { LDClientTracking } from '../src/api/client/LDClientTracking';
 import BrowserTelemetryImpl from '../src/BrowserTelemetryImpl';
 import { ParsedOptions } from '../src/options';
@@ -210,6 +211,30 @@ it('unregisters collectors on close', () => {
   expect(mockCollector.unregister).toHaveBeenCalled();
 });
 
+it('logs event dropped message when maxPendingEvents is reached', () => {
+  const mockLogger = {
+    warn: jest.fn(),
+  };
+  const telemetry = new BrowserTelemetryImpl({
+    ...defaultOptions,
+    maxPendingEvents: 2,
+    logger: mockLogger,
+  });
+  telemetry.captureError(new Error('Test error'));
+  expect(mockLogger.warn).not.toHaveBeenCalled();
+  telemetry.captureError(new Error('Test error 2'));
+  expect(mockLogger.warn).not.toHaveBeenCalled();
+
+  telemetry.captureError(new Error('Test error 3'));
+  expect(mockLogger.warn).toHaveBeenCalledWith(
+    'LaunchDarkly - Browser Telemetry: Maximum pending events reached. Old events will be dropped until the SDK' +
+      ' client is registered.',
+  );
+
+  telemetry.captureError(new Error('Test error 4'));
+  expect(mockLogger.warn).toHaveBeenCalledTimes(1);
+});
+
 it('filters breadcrumbs using provided filters', () => {
   const options: ParsedOptions = {
     ...defaultOptions,
@@ -359,3 +384,141 @@ it('omits breadcrumbs when a filter is not a function', () => {
     }),
   );
 });
+
+it('warns when a breadcrumb filter is not a function', () => {
+  const mockLogger = {
+    warn: jest.fn(),
+  };
+  const options: ParsedOptions = {
+    ...defaultOptions,
+    // @ts-ignore
+    breadcrumbs: { ...defaultOptions.breadcrumbs, filters: ['potato'] },
+    logger: mockLogger,
+  };
+
+  const telemetry = new BrowserTelemetryImpl(options);
+  telemetry.addBreadcrumb({
+    type: 'custom',
+    data: { id: 1 },
+    timestamp: Date.now(),
+    class: 'custom',
+    level: 'info',
+  });
+
+  expect(mockLogger.warn).toHaveBeenCalledWith(
+    'LaunchDarkly - Browser Telemetry: Error applying breadcrumb filters: TypeError: filter is not a function',
+  );
+});
+
+it('warns when a breadcrumb filter throws an exception', () => {
+  const mockLogger = {
+    warn: jest.fn(),
+  };
+  const options: ParsedOptions = {
+    ...defaultOptions,
+    breadcrumbs: {
+      ...defaultOptions.breadcrumbs,
+      filters: [
+        () => {
+          throw new Error('Filter error');
+        },
+      ],
+    },
+    logger: mockLogger,
+  };
+
+  const telemetry = new BrowserTelemetryImpl(options);
+  telemetry.addBreadcrumb({
+    type: 'custom',
+    data: { id: 1 },
+    timestamp: Date.now(),
+    class: 'custom',
+    level: 'info',
+  });
+
+  expect(mockLogger.warn).toHaveBeenCalledWith(
+    'LaunchDarkly - Browser Telemetry: Error applying breadcrumb filters: Error: Filter error',
+  );
+});
+
+it('only logs breadcrumb filter error once', () => {
+  const mockLogger = {
+    warn: jest.fn(),
+  };
+  const options: ParsedOptions = {
+    ...defaultOptions,
+    breadcrumbs: {
+      ...defaultOptions.breadcrumbs,
+      filters: [
+        () => {
+          throw new Error('Filter error');
+        },
+      ],
+    },
+    logger: mockLogger,
+  };
+
+  const telemetry = new BrowserTelemetryImpl(options);
+
+  // Add multiple breadcrumbs that will trigger the filter error
+  telemetry.addBreadcrumb({
+    type: 'custom',
+    data: { id: 1 },
+    timestamp: Date.now(),
+    class: 'custom',
+    level: 'info',
+  });
+
+  telemetry.addBreadcrumb({
+    type: 'custom',
+    data: { id: 2 },
+    timestamp: Date.now(),
+    class: 'custom',
+    level: 'info',
+  });
+
+  // Verify warning was only logged once
+  expect(mockLogger.warn).toHaveBeenCalledTimes(1);
+  expect(mockLogger.warn).toHaveBeenCalledWith(
+    'LaunchDarkly - Browser Telemetry: Error applying breadcrumb filters: Error: Filter error',
+  );
+});
+
+it('uses the client logger when no logger is provided', () => {
+  const options: ParsedOptions = {
+    ...defaultOptions,
+    breadcrumbs: {
+      ...defaultOptions.breadcrumbs,
+      filters: [
+        () => {
+          throw new Error('Filter error');
+        },
+      ],
+    },
+  };
+
+  const telemetry = new BrowserTelemetryImpl(options);
+
+  const mockClientWithLogging: jest.Mocked<LDClientLogging & LDClientTracking> = {
+    logger: {
+      warn: jest.fn(),
+    },
+    track: jest.fn(),
+  };
+
+  telemetry.register(mockClientWithLogging);
+
+  // Add multiple breadcrumbs that will trigger the filter error
+  telemetry.addBreadcrumb({
+    type: 'custom',
+    data: { id: 1 },
+    timestamp: Date.now(),
+    class: 'custom',
+    level: 'info',
+  });
+
+  expect(mockClientWithLogging.logger.warn).toHaveBeenCalledTimes(1);
+  expect(mockClientWithLogging.logger.warn).toHaveBeenCalledWith(
+    'LaunchDarkly - Browser Telemetry: Error applying breadcrumb filters: Error: Filter error',
+  );
+});

packages/telemetry/browser-telemetry/__tests__/logging.test.ts

@@ -0,0 +1,52 @@
+import { MinLogger } from '../src/api';
+import { fallbackLogger, prefixLog, safeMinLogger } from '../src/logging';
+
+afterEach(() => {
+  jest.resetAllMocks();
+});
+
+it('prefixes the message with the telemetry prefix', () => {
+  const message = 'test message';
+  const prefixed = prefixLog(message);
+  expect(prefixed).toBe('LaunchDarkly - Browser Telemetry: test message');
+});
+
+it('uses fallback logger when no logger provided', () => {
+  const spy = jest.spyOn(fallbackLogger, 'warn');
+  const logger = safeMinLogger(undefined);
+
+  logger.warn('test message');
+
+  expect(spy).toHaveBeenCalledWith('test message');
+  spy.mockRestore();
+});
+
+it('uses provided logger when it works correctly', () => {
+  const mockWarn = jest.fn();
+  const testLogger: MinLogger = {
+    warn: mockWarn,
+  };
+
+  const logger = safeMinLogger(testLogger);
+  logger.warn('test message');
+
+  expect(mockWarn).toHaveBeenCalledWith('test message');
+});
+
+it('falls back to fallback logger when provided logger throws', () => {
+  const spy = jest.spyOn(fallbackLogger, 'warn');
+  const testLogger: MinLogger = {
+    warn: () => {
+      throw new Error('logger error');
+    },
+  };
+
+  const logger = safeMinLogger(testLogger);
+  logger.warn('test message');
+
+  expect(spy).toHaveBeenCalledWith('test message');
+  expect(spy).toHaveBeenCalledWith(
+    'LaunchDarkly - Browser Telemetry: The provided logger threw an exception, using fallback logger.',
+  );
+  spy.mockRestore();
+});

packages/telemetry/browser-telemetry/__tests__/options.test.ts

@@ -63,7 +63,7 @@ it('warns when maxPendingEvents is not a number', () => {
 
   expect(outOptions.maxPendingEvents).toEqual(defaultOptions().maxPendingEvents);
   expect(mockLogger.warn).toHaveBeenCalledWith(
-    'Config option "maxPendingEvents" should be of type number, got string, using default value',
+    'LaunchDarkly - Browser Telemetry: Config option "maxPendingEvents" should be of type number, got string, using default value',
   );
 });
 
@@ -90,7 +90,7 @@ it('warns when breadcrumbs config is not an object', () => {
 
   expect(outOptions.breadcrumbs).toEqual(defaultOptions().breadcrumbs);
   expect(mockLogger.warn).toHaveBeenCalledWith(
-    'Config option "breadcrumbs" should be of type object, got string, using default value',
+    'LaunchDarkly - Browser Telemetry: Config option "breadcrumbs" should be of type object, got string, using default value',
   );
 });
 
@@ -105,7 +105,7 @@ it('warns when collectors is not an array', () => {
 
   expect(outOptions.collectors).toEqual(defaultOptions().collectors);
   expect(mockLogger.warn).toHaveBeenCalledWith(
-    'Config option "collectors" should be of type Collector[], got string, using default value',
+    'LaunchDarkly - Browser Telemetry: Config option "collectors" should be of type Collector[], got string, using default value',
   );
 });
 
@@ -133,7 +133,7 @@ it('warns when stack config is not an object', () => {
 
   expect(outOptions.stack).toEqual(defaultOptions().stack);
   expect(mockLogger.warn).toHaveBeenCalledWith(
-    'Config option "stack" should be of type object, got string, using default value',
+    'LaunchDarkly - Browser Telemetry: Config option "stack" should be of type object, got string, using default value',
   );
 });
 
@@ -152,7 +152,7 @@ it('warns when breadcrumbs.maxBreadcrumbs is not a number', () => {
     defaultOptions().breadcrumbs.maxBreadcrumbs,
   );
   expect(mockLogger.warn).toHaveBeenCalledWith(
-    'Config option "breadcrumbs.maxBreadcrumbs" should be of type number, got string, using default value',
+    'LaunchDarkly - Browser Telemetry: Config option "breadcrumbs.maxBreadcrumbs" should be of type number, got string, using default value',
   );
 });
 
@@ -183,7 +183,7 @@ it('warns when breadcrumbs.click is not boolean', () => {
 
   expect(outOptions.breadcrumbs.click).toEqual(defaultOptions().breadcrumbs.click);
   expect(mockLogger.warn).toHaveBeenCalledWith(
-    'Config option "breadcrumbs.click" should be of type boolean, got string, using default value',
+    'LaunchDarkly - Browser Telemetry: Config option "breadcrumbs.click" should be of type boolean, got string, using default value',
   );
 });
 
@@ -200,7 +200,7 @@ it('warns when breadcrumbs.evaluations is not boolean', () => {
 
   expect(outOptions.breadcrumbs.evaluations).toEqual(defaultOptions().breadcrumbs.evaluations);
   expect(mockLogger.warn).toHaveBeenCalledWith(
-    'Config option "breadcrumbs.evaluations" should be of type boolean, got string, using default value',
+    'LaunchDarkly - Browser Telemetry: Config option "breadcrumbs.evaluations" should be of type boolean, got string, using default value',
   );
 });
 
@@ -217,7 +217,7 @@ it('warns when breadcrumbs.flagChange is not boolean', () => {
 
   expect(outOptions.breadcrumbs.flagChange).toEqual(defaultOptions().breadcrumbs.flagChange);
   expect(mockLogger.warn).toHaveBeenCalledWith(
-    'Config option "breadcrumbs.flagChange" should be of type boolean, got string, using default value',
+    'LaunchDarkly - Browser Telemetry: Config option "breadcrumbs.flagChange" should be of type boolean, got string, using default value',
   );
 });
 
@@ -234,7 +234,7 @@ it('warns when breadcrumbs.keyboardInput is not boolean', () => {
 
   expect(outOptions.breadcrumbs.keyboardInput).toEqual(defaultOptions().breadcrumbs.keyboardInput);
   expect(mockLogger.warn).toHaveBeenCalledWith(
-    'Config option "breadcrumbs.keyboardInput" should be of type boolean, got string, using default value',
+    'LaunchDarkly - Browser Telemetry: Config option "breadcrumbs.keyboardInput" should be of type boolean, got string, using default value',
   );
 });
 
@@ -307,7 +307,7 @@ it('warns when breadcrumbs.http is not an object', () => {
 
   expect(outOptions.breadcrumbs.http).toEqual(defaultOptions().breadcrumbs.http);
   expect(mockLogger.warn).toHaveBeenCalledWith(
-    'Config option "breadcrumbs.http" should be of type HttpBreadCrumbOptions | false, got string, using default value',
+    'LaunchDarkly - Browser Telemetry: Config option "breadcrumbs.http" should be of type HttpBreadCrumbOptions | false, got string, using default value',
   );
 });
 
@@ -328,7 +328,7 @@ it('warns when breadcrumbs.http.instrumentFetch is not boolean', () => {
     defaultOptions().breadcrumbs.http.instrumentFetch,
   );
   expect(mockLogger.warn).toHaveBeenCalledWith(
-    'Config option "breadcrumbs.http.instrumentFetch" should be of type boolean, got string, using default value',
+    'LaunchDarkly - Browser Telemetry: Config option "breadcrumbs.http.instrumentFetch" should be of type boolean, got string, using default value',
   );
 });
 
@@ -349,7 +349,7 @@ it('warns when breadcrumbs.http.instrumentXhr is not boolean', () => {
     defaultOptions().breadcrumbs.http.instrumentXhr,
   );
   expect(mockLogger.warn).toHaveBeenCalledWith(
-    'Config option "breadcrumbs.http.instrumentXhr" should be of type boolean, got string, using default value',
+    'LaunchDarkly - Browser Telemetry: Config option "breadcrumbs.http.instrumentXhr" should be of type boolean, got string, using default value',
   );
 });
 
@@ -419,7 +419,7 @@ it('warns when breadcrumbs.http.customUrlFilter is not a function', () => {
 
   expect(outOptions.breadcrumbs.http.customUrlFilter).toBeUndefined();
   expect(mockLogger.warn).toHaveBeenCalledWith(
-    'The "breadcrumbs.http.customUrlFilter" must be a function. Received string',
+    'LaunchDarkly - Browser Telemetry: The "breadcrumbs.http.customUrlFilter" must be a function. Received string',
   );
 });
 
@@ -435,6 +435,6 @@ it('warns when filters is not an array', () => {
   );
   expect(outOptions.breadcrumbs.filters).toEqual([]);
   expect(mockLogger.warn).toHaveBeenCalledWith(
-    'Config option "breadcrumbs.filters" should be of type array, got string, using default value',
+    'LaunchDarkly - Browser Telemetry: Config option "breadcrumbs.filters" should be of type array, got string, using default value',
   );
 });