feat(flags): switch local evaluation endpoint to /flags/definitions (#173)

* feat(flags): switch local evaluation endpoint to /flags/definitions

* refactor(tests): deduplicate LocalEvaluationUrl into single internal constant

Author: patricio-posthog

src/PostHog/Api/LocalEvaluationApiResult.cs

@@ -5,7 +5,7 @@
 namespace PostHog.Api;
 
 /// <summary>
-/// The API Payload from the <c>/api/feature_flag/local_evaluation</c> endpoint used to evaluate feature flags
+/// The API Payload from the <c>/flags/definitions</c> endpoint used to evaluate feature flags
 /// locally.
 /// </summary>
 internal record LocalEvaluationApiResult

src/PostHog/Api/PostHogApiClient.cs

@@ -144,7 +144,7 @@ public async Task<ApiResult> SendEventAsync(
 
     /// <summary>
     /// Retrieves all the feature flags for the project by making a request to the
-    /// <c>/api/feature_flag/local_evaluation</c> endpoint. This requires that a Personal API Key is set in
+    /// <c>/flags/definitions</c> endpoint. This requires that a Personal API Key is set in
     /// <see cref="PostHogOptions"/>.
     /// </summary>
     /// <param name="etag">Optional ETag from a previous request for conditional fetching.</param>
@@ -155,7 +155,7 @@ public async Task<LocalEvaluationResponse> GetFeatureFlagsForLocalEvaluationAsyn
         string? etag,
         CancellationToken cancellationToken)
     {
-        var uriBuilder = new UriBuilder(new Uri(HostUrl, "/api/feature_flag/local_evaluation"))
+        var uriBuilder = new UriBuilder(new Uri(HostUrl, "/flags/definitions"))
         {
             Query = $"token={Uri.EscapeDataString(ProjectApiKey)}&send_cohorts"
         };

tests/TestLibrary/Fakes/FakeHttpMessageHandlerExtensions.cs

@@ -68,7 +68,7 @@ public static void AddRepeatedFlagsResponse(this FakeHttpMessageHandler handler,
     public static void AddRepeatedFlagsResponse(this FakeHttpMessageHandler handler, int count, string responseBody)
         => handler.AddRepeatedFlagsResponse(count, _ => responseBody);
 
-    static readonly Uri LocalEvaluationUrl = new("https://us.i.posthog.com/api/feature_flag/local_evaluation?token=fake-project-api-key&send_cohorts");
+    internal static readonly Uri LocalEvaluationUrl = new("https://us.i.posthog.com/flags/definitions?token=fake-project-api-key&send_cohorts");
 
     public static FakeHttpMessageHandler.RequestHandler AddLocalEvaluationResponse(
         this FakeHttpMessageHandler handler,

tests/UnitTests/Features/FeatureFlagsTests.cs

@@ -3354,7 +3354,7 @@ public async Task ReturnsEmptyDictionaryWhenPersonalApiKeyIncorrect()
             FeatureFlagPayloads = new Dictionary<string, string>(),
         });
         container.FakeHttpMessageHandler.AddResponse(
-            new Uri("https://us.i.posthog.com/api/feature_flag/local_evaluation?token=fake-project-api-key&send_cohorts"),
+            FakeHttpMessageHandlerExtensions.LocalEvaluationUrl,
             HttpMethod.Get,
             new HttpResponseMessage(HttpStatusCode.Unauthorized)
             {
@@ -3510,7 +3510,7 @@ public async Task ReturnsEmptyDictionaryWhenLocalEvaluationQuotaExceeded()
         // When local evaluation is quota limited, we do not want to fallback to /decide.
         var decideHandler = container.FakeHttpMessageHandler.AddFlagsResponseException(new InvalidOperationException());
         container.FakeHttpMessageHandler.AddResponse(
-            new Uri("https://us.i.posthog.com/api/feature_flag/local_evaluation?token=fake-project-api-key&send_cohorts"),
+            FakeHttpMessageHandlerExtensions.LocalEvaluationUrl,
             HttpMethod.Get,
             new HttpResponseMessage(HttpStatusCode.PaymentRequired)
             {
@@ -3542,7 +3542,7 @@ public async Task ReturnsFalseWhenSingleFlagLocalEvaluationRequestQuotaExceeded(
         var container = new TestContainer("fake-personal-api-key");
         var decideHandler = container.FakeHttpMessageHandler.AddFlagsResponseException(new InvalidOperationException());
         container.FakeHttpMessageHandler.AddResponse(
-            new Uri("https://us.i.posthog.com/api/feature_flag/local_evaluation?token=fake-project-api-key&send_cohorts"),
+            FakeHttpMessageHandlerExtensions.LocalEvaluationUrl,
             HttpMethod.Get,
             new HttpResponseMessage(HttpStatusCode.PaymentRequired)
             {

tests/UnitTests/Features/LocalFeatureFlagsLoaderTests.cs

@@ -29,8 +29,7 @@ public class TheDisposeAsyncMethod
         }
         """;
 
-    static readonly Uri LocalEvaluationUrl =
-        new("https://us.i.posthog.com/api/feature_flag/local_evaluation?token=fake-project-api-key&send_cohorts");
+    static readonly Uri LocalEvaluationUrl = FakeHttpMessageHandlerExtensions.LocalEvaluationUrl;
 
     [Fact]
     public async Task CompletesGracefullyDuringInFlightPoll()

tests/UnitTests/PostHogClientTests.cs

@@ -1510,7 +1510,7 @@ public async Task RespectsCancellationToken()
     {
         var container = new TestContainer(personalApiKey: "fake-personal-api-key");
         // Add a handler that will throw OperationCanceledException
-        var uri = new Uri("https://us.i.posthog.com/api/feature_flag/local_evaluation?token=fake-project-api-key&send_cohorts");
+        var uri = FakeHttpMessageHandlerExtensions.LocalEvaluationUrl;
         container.FakeHttpMessageHandler.AddResponseException(uri, HttpMethod.Get, new OperationCanceledException());
         var client = container.Activate<PostHogClient>();
 
@@ -1529,7 +1529,7 @@ public async Task DoesNotLogErrorForCancellation()
     {
         var container = new TestContainer(personalApiKey: "fake-personal-api-key");
         // Add a handler that will throw OperationCanceledException
-        var uri = new Uri("https://us.i.posthog.com/api/feature_flag/local_evaluation?token=fake-project-api-key&send_cohorts");
+        var uri = FakeHttpMessageHandlerExtensions.LocalEvaluationUrl;
         container.FakeHttpMessageHandler.AddResponseException(uri, HttpMethod.Get, new OperationCanceledException());
         var client = container.Activate<PostHogClient>();