test: domain-layer characterization suite (25 -> 165 tests)

app/build.gradle.kts

@@ -101,6 +101,8 @@ dependencies {
     testImplementation(libs.robolectric)
     testImplementation(libs.androidx.test.core)
     testImplementation(libs.kotlinx.coroutines.test)
+    testImplementation(libs.turbine)
+    testImplementation(libs.mockk)
     androidTestImplementation(libs.androidx.junit)
     androidTestImplementation(libs.androidx.room.testing)
     androidTestImplementation(libs.androidx.test.core)

app/src/main/java/com/jdluu/flexinsight/data/ai/HevyAiDataAccessor.kt

@@ -11,6 +11,7 @@ import com.jdluu.flexinsight.data.repository.FlexRepository
 import com.jdluu.flexinsight.data.repository.RoutineRepository
 import com.jdluu.flexinsight.data.repository.StatsRepository
 import com.jdluu.flexinsight.data.repository.WorkoutRepository
+import com.jdluu.flexinsight.domain.ai.AiContextProvider
 import kotlinx.coroutines.flow.first
 import java.text.SimpleDateFormat
 import java.util.Date
@@ -35,7 +36,7 @@ class HevyAiDataAccessor @Inject constructor(
     private val userPreferencesManager: UserPreferencesManager,
     private val apiKeyManager: ApiKeyManager,
     private val healthConnectRepository: HealthConnectRepository
-) {
+) : AiContextProvider {
 
     data class ContextSnapshot(
         val text: String,
@@ -46,7 +47,7 @@ class HevyAiDataAccessor @Inject constructor(
         val usesLiveExerciseHistory: Boolean = false
     )
 
-    suspend fun buildContext(userQuery: String? = null): ContextSnapshot {
+    override suspend fun buildContext(userQuery: String?): ContextSnapshot {
         val hasApiKey = apiKeyManager.hasApiKey()
         val workoutCount = try {
             flexRepository.getWorkoutCount().first()

app/src/main/java/com/jdluu/flexinsight/di/AiModule.kt

@@ -2,6 +2,8 @@ package com.jdluu.flexinsight.di
 
 import com.jdluu.flexinsight.data.ai.FlexAIClient
 import com.jdluu.flexinsight.data.ai.GeminiNanoClient
+import com.jdluu.flexinsight.data.ai.HevyAiDataAccessor
+import com.jdluu.flexinsight.domain.ai.AiContextProvider
 import dagger.Binds
 import dagger.Module
 import dagger.hilt.InstallIn
@@ -17,4 +19,10 @@ abstract class AiModule {
     abstract fun bindFlexAIClient(
         geminiNanoClient: GeminiNanoClient
     ): FlexAIClient
+
+    @Binds
+    @Singleton
+    abstract fun bindAiContextProvider(
+        hevyAiDataAccessor: HevyAiDataAccessor
+    ): AiContextProvider
 }

app/src/main/java/com/jdluu/flexinsight/domain/ai/AiContextProvider.kt

@@ -0,0 +1,18 @@
+package com.jdluu.flexinsight.domain.ai
+
+import com.jdluu.flexinsight.data.ai.HevyAiDataAccessor
+
+/**
+ * Source of AI prompt context built from user workout data.
+ *
+ * Extracted from [HevyAiDataAccessor] so domain code depends on an abstraction
+ * rather than the Hevy-specific implementation.
+ */
+interface AiContextProvider {
+    /**
+     * Builds the system prompt context snapshot.
+     *
+     * @param userQuery When set, triggers live Hevy API exercise-history lookups for relevant lifts.
+     */
+    suspend fun buildContext(userQuery: String? = null): HevyAiDataAccessor.ContextSnapshot
+}

app/src/main/java/com/jdluu/flexinsight/domain/usecase/BuildAiContextUseCase.kt

@@ -1,6 +1,7 @@
 package com.jdluu.flexinsight.domain.usecase
 
 import com.jdluu.flexinsight.data.ai.HevyAiDataAccessor
+import com.jdluu.flexinsight.domain.ai.AiContextProvider
 import javax.inject.Inject
 
 /**
@@ -9,9 +10,9 @@ import javax.inject.Inject
  * @param userQuery When set, triggers live Hevy API exercise-history lookups for relevant lifts.
  */
 class BuildAiContextUseCase @Inject constructor(
-    private val hevyAiDataAccessor: HevyAiDataAccessor
+    private val aiContextProvider: AiContextProvider
 ) {
     suspend operator fun invoke(userQuery: String? = null): HevyAiDataAccessor.ContextSnapshot {
-        return hevyAiDataAccessor.buildContext(userQuery)
+        return aiContextProvider.buildContext(userQuery)
     }
 }

app/src/test/java/com/jdluu/flexinsight/domain/usecase/BuildAiContextUseCaseTest.kt

@@ -0,0 +1,53 @@
+package com.jdluu.flexinsight.domain.usecase
+
+import com.jdluu.flexinsight.data.ai.HevyAiDataAccessor
+import com.jdluu.flexinsight.domain.ai.AiContextProvider
+import kotlinx.coroutines.test.runTest
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertSame
+import org.junit.Test
+
+class BuildAiContextUseCaseTest {
+
+    private fun snapshot(text: String, usesLive: Boolean = false) = HevyAiDataAccessor.ContextSnapshot(
+        text = text,
+        hasWorkoutData = true,
+        hasApiKey = true,
+        workoutCount = 42,
+        usesLiveExerciseHistory = usesLive
+    )
+
+    private class FakeContextProvider : AiContextProvider {
+        var lastQuery: String? = null
+        lateinit var response: HevyAiDataAccessor.ContextSnapshot
+
+        override suspend fun buildContext(userQuery: String?): HevyAiDataAccessor.ContextSnapshot {
+            lastQuery = userQuery
+            return response
+        }
+    }
+
+    @Test
+    fun `delegates to provider with null query by default`() = runTest {
+        val provider = FakeContextProvider()
+        val expected = snapshot("context text")
+        provider.response = expected
+
+        val result = BuildAiContextUseCase(provider)()
+
+        assertEquals(expected, result)
+        assertEquals(null, provider.lastQuery)
+    }
+
+    @Test
+    fun `forwards non-null user query to provider`() = runTest {
+        val provider = FakeContextProvider()
+        val expected = snapshot("live history context", usesLive = true)
+        provider.response = expected
+
+        val result = BuildAiContextUseCase(provider)(userQuery = "how is my bench?")
+
+        assertSame(expected, result)
+        assertEquals("how is my bench?", provider.lastQuery)
+    }
+}