add warning for bootstrap not having metadata

Author: eli-darkly

src/__tests__/LDClient-test.js

@@ -175,6 +175,14 @@ describe('LDClient', () => {
       expect(client.variation('foo')).toEqual('bar');
     });
 
+    it('logs warning when bootstrap object uses old format', () => {
+      const client = LDClient.initialize(envName, user, {
+        bootstrap: { foo: 'bar' },
+      });
+
+      expect(warnSpy).toHaveBeenCalledWith(messages.bootstrapOldFormat());
+    });
+
     it('sets flag values from bootstrap object with new format', () => {
       const client = LDClient.initialize(envName, user, {
         bootstrap: { foo: 'bar', $flagsState: { foo: { version: 1 } } },
@@ -183,6 +191,14 @@ describe('LDClient', () => {
       expect(client.variation('foo')).toEqual('bar');
     });
 
+    it('does not log warning when bootstrap object uses new format', () => {
+      const client = LDClient.initialize(envName, user, {
+        bootstrap: { foo: 'bar', $flagsState: { foo: { version: 1 } } },
+      });
+
+      expect(warnSpy).not.toHaveBeenCalled();
+    });
+
     it('should contain package version', () => {
       // Arrange
       const version = LDClient.version;

src/index.js

@@ -39,11 +39,15 @@ export function initialize(env, user, options = {}) {
     // If the bootstrap data came from an older server-side SDK, we'll have just a map of keys to values.
     // Newer SDKs that have an allFlagsState method will provide an extra "$flagsState" key that contains
     // the rest of the metadata we want. We do it this way for backward compatibility with older JS SDKs.
+    const keys = Object.keys(data);
     const metadataKey = '$flagsState';
     const metadata = data[metadataKey];
+    if (!metadata && keys.length) {
+      console.warn(messages.bootstrapOldFormat());
+    }
     const ret = {};
-    for (const key in data) {
-      if (key !== metadataKey && data.hasOwnProperty(key)) {
+    keys.forEach(function(key) {
+      if (key !== metadataKey) {
         let flag = { value: data[key] };
         if (metadata && metadata[key]) {
           flag = utils.extend(flag, metadata[key]);
@@ -52,7 +56,7 @@ export function initialize(env, user, options = {}) {
         }
         ret[key] = flag;
       }
-    }
+    });
     return ret;
   }
 

src/messages.js

@@ -37,6 +37,10 @@ export const invalidUser = function() {
   return 'Invalid user specified.' + docLink;
 };
 
+export const bootstrapOldFormat = function() {
+  'LaunchDarkly client was initialized with bootstrap data that did not include flag metadata. Events may not be sent correctly.' + docLink;
+};
+
 export const deprecated = function(oldName, newName) {
   return '[LaunchDarkly] "' + oldName + '" is deprecated, please use "' + newName + '"';
 };