fix: Exit from rearrangeEventsForLatestFunctionResponse if size of events is less than 2

google-genai-bot · copybara-github · commit 5bc3ef89e62e · 2026-03-03T03:00:33.000-08:00
PiperOrigin-RevId: 877845164
diff --git a/core/src/main/java/com/google/adk/flows/llmflows/Contents.java b/core/src/main/java/com/google/adk/flows/llmflows/Contents.java
@@ -406,6 +406,11 @@ private static boolean isEventBelongsToBranch(Optional<String> invocationBranchO
    * @return A new list of events with the appropriate rearrangement.
    */
   private static List<Event> rearrangeEventsForLatestFunctionResponse(List<Event> events) {
+    if (events.size() < 2) {
+      // No need to process, since there is no function_call.
+      return events;
+    }
+
     // TODO: b/412663475 - Handle parallel function calls within the same event. Currently, this
     // throws an error.
     if (events.isEmpty() || Iterables.getLast(events).functionResponses().isEmpty()) {
diff --git a/core/src/test/java/com/google/adk/flows/llmflows/ContentsTest.java b/core/src/test/java/com/google/adk/flows/llmflows/ContentsTest.java
@@ -142,7 +142,9 @@ public void rearrangeLatest_multipleFRsForSameFCAsync_returnsMergedFR() {
   @Test
   public void rearrangeLatest_missingFCEvent_throwsException() {
     Event frEvent = createFunctionResponseEvent("fr1", "tool1", "call1");
-    ImmutableList<Event> events = ImmutableList.of(createUserEvent("u1", "Query"), frEvent);
+    Event frEvent2 = createFunctionResponseEvent("fr2", "tool1", "call1");
+    ImmutableList<Event> events =
+        ImmutableList.of(createUserEvent("u1", "Query"), frEvent, frEvent2);
 
     assertThrows(IllegalStateException.class, () -> runContentsProcessor(events));
   }
@@ -473,10 +475,12 @@ public void processRequest_includeContentsNone_asyncFRAcrossTurns_throwsExceptio
     Event fc1 = createFunctionCallEvent("fc1", "tool1", "call1");
     Event u2 = createUserEvent("u2", "Query 2");
     Event fr1 = createFunctionResponseEvent("fr1", "tool1", "call1"); // FR for fc1
+    Event fr2 = createFunctionResponseEvent("fr2", "tool2", "call1"); // FR for fc2
 
-    ImmutableList<Event> events = ImmutableList.of(u1, fc1, u2, fr1);
+    ImmutableList<Event> events = ImmutableList.of(u1, fc1, u2, fr1, fr2);
 
-    // The current turn starts from u2. fc1 is not in the sublist [u2, fr1], so rearrangement fails.
+    // The current turn starts from u2. fc1 is not in the sublist [u2, fr1, fr2], so rearrangement
+    // fails.
     IllegalStateException e =
         assertThrows(
             IllegalStateException.class,
@@ -486,6 +490,19 @@ public void processRequest_includeContentsNone_asyncFRAcrossTurns_throwsExceptio
         .contains("No function call event found for function response IDs: [call1]");
   }
 
+  @Test
+  public void processRequest_notEnoughEvents_returnsOriginalList() {
+    Event fr1 =
+        createFunctionCallAndResponseEvent(
+            "fr1", "tool1", "call1", ImmutableMap.of("result", "ok"), "user");
+
+    ImmutableList<Event> events = ImmutableList.of(fr1);
+
+    List<Content> result =
+        runContentsProcessorWithIncludeContents(events, LlmAgent.IncludeContents.NONE, "A2A-agent");
+    assertThat(result).isEmpty();
+  }
+
   @Test
   public void processRequest_includeContentsNone_asyncFRWithinTurn() {
     Event u1 = createUserEvent("u1", "Query 1");
@@ -883,13 +900,40 @@ private static Event createFunctionResponseEvent(
         .build();
   }
 
+  private static Event createFunctionCallAndResponseEvent(
+      String id, String toolName, String callId, Map<String, Object> response, String author) {
+    return Event.builder()
+        .id(id)
+        .author(author)
+        .invocationId("invocationId")
+        .content(
+            Content.fromParts(
+                Part.builder()
+                    .functionCall(FunctionCall.builder().name(toolName).id(callId).build())
+                    .build(),
+                Part.builder()
+                    .functionResponse(
+                        FunctionResponse.builder()
+                            .name(toolName)
+                            .id(callId)
+                            .response(response)
+                            .build())
+                    .build()))
+        .build();
+  }
+
   private List<Content> runContentsProcessor(List<Event> events) {
     return runContentsProcessorWithIncludeContents(events, LlmAgent.IncludeContents.DEFAULT);
   }
 
   private List<Content> runContentsProcessorWithIncludeContents(
       List<Event> events, LlmAgent.IncludeContents includeContents) {
-    LlmAgent agent = LlmAgent.builder().name(AGENT).includeContents(includeContents).build();
+    return runContentsProcessorWithIncludeContents(events, includeContents, AGENT);
+  }
+
+  private List<Content> runContentsProcessorWithIncludeContents(
+      List<Event> events, LlmAgent.IncludeContents includeContents, String agentName) {
+    LlmAgent agent = LlmAgent.builder().name(agentName).includeContents(includeContents).build();
     Session session =
         sessionService.createSession("test-app", "test-user", null, "test-session").blockingGet();
     session.events().addAll(events);
