Add tests for streaming chat sesssions for thought signatures

firebase-ai/src/test/java/com/google/firebase/ai/ChatTest.kt

@@ -0,0 +1,130 @@
+/*
+ * Copyright 2025 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.firebase.ai
+
+import com.google.firebase.FirebaseApp
+import com.google.firebase.ai.common.APIController
+import com.google.firebase.ai.common.util.doBlocking
+import com.google.firebase.ai.type.RequestOptions
+import com.google.firebase.ai.type.TextPart
+import io.ktor.client.engine.mock.MockEngine
+import io.ktor.client.engine.mock.respond
+import io.ktor.http.HttpHeaders
+import io.ktor.http.HttpStatusCode
+import io.ktor.http.headersOf
+import kotlin.time.Duration.Companion.seconds
+import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.withTimeout
+import org.junit.Before
+import org.junit.Test
+import org.mockito.Mockito
+import com.google.common.truth.Truth.assertThat
+import com.google.firebase.ai.type.content
+
+class ChatTest {
+    private val TEST_CLIENT_ID = "test"
+    private val TEST_APP_ID = "1:android:12345"
+    private val TEST_VERSION = 1
+
+    private var mockFirebaseApp: FirebaseApp = Mockito.mock<FirebaseApp>()
+
+    @Before
+    fun setup() {
+        Mockito.`when`(mockFirebaseApp.isDataCollectionDefaultEnabled).thenReturn(false)
+    }
+
+    @Test
+    fun `sendMessageStream preserves thoughtSignature in history`() = doBlocking {
+        val mockResponse = """
+            [
+              {
+                "candidates": [
+                  {
+                    "content": {
+                      "role": "model",
+                      "parts": [
+                        {
+                          "text": "This is a thought.",
+                          "thought": true,
+                          "thoughtSignature": "thought1"
+                        }
+                      ]
+                    }
+                  }
+                ]
+              },
+              {
+                "candidates": [
+                  {
+                    "content": {
+                      "role": "model",
+                      "parts": [
+                        {
+                          "text": "This is not a thought."
+                        }
+                      ]
+                    }
+                  }
+                ]
+              }
+            ]
+        """.trimIndent()
+        val mockEngine = MockEngine {
+            respond(
+                mockResponse,
+                HttpStatusCode.OK,
+                headersOf(HttpHeaders.ContentType, "application/json")
+            )
+        }
+
+        val apiController =
+            APIController(
+                "super_cool_test_key",
+                "gemini-2.5-flash",
+                RequestOptions(timeout = 5.seconds),
+                mockEngine,
+                TEST_CLIENT_ID,
+                mockFirebaseApp,
+                TEST_VERSION,
+                TEST_APP_ID,
+                null,
+            )
+
+        val generativeModel =
+            GenerativeModel(
+                "gemini-2.5-flash",
+                controller = apiController
+            )
+        val chat = Chat(generativeModel)
+
+        withTimeout(5.seconds) {
+            chat.sendMessageStream("my test prompt").collect()
+        }
+
+        val history = chat.history
+        assertThat(history).hasSize(2)
+        val modelResponse = history[1]
+        assertThat(modelResponse.role).isEqualTo("model")
+        assertThat(modelResponse.parts).hasSize(2)
+        val thoughtPart = modelResponse.parts[0] as TextPart
+        assertThat(thoughtPart.isThought).isTrue()
+        assertThat(thoughtPart.thoughtSignature).isEqualTo("thought1")
+        val textPart = modelResponse.parts[1] as TextPart
+        assertThat(textPart.isThought).isFalse()
+        assertThat(textPart.thoughtSignature).isNull()
+    }
+}