Add API to support saving local only resources

engine/src/main/java/com/google/android/fhir/FhirEngine.kt

@@ -66,11 +66,12 @@ interface FhirEngine {
    * [create], the resource created in `FhirEngine` will have the same `id`. If no `id` is
    * specified, `FhirEngine` will generate a UUID as that resource's `id` and include it in the
    * returned list of IDs.
-   *
    * @param resource The FHIR resources to create.
+   * @param isLocalOnly - Setting the value to [true] instructs engine that the resource and its
+   *   subsequent updates should never be synced to the server.
    * @return A list of logical IDs of the newly created resources.
    */
-  suspend fun create(vararg resource: Resource): List<String>
+  suspend fun create(vararg resource: Resource, isLocalOnly: Boolean = false): List<String>
 
   /**
    * Loads a FHIR resource given its [ResourceType] and logical ID.

engine/src/main/java/com/google/android/fhir/db/Database.kt

@@ -39,6 +39,15 @@ internal interface Database {
    */
   suspend fun <R : Resource> insert(vararg resource: R): List<String>
 
+  /**
+   * Inserts a list of local `resources` into the FHIR resource database. If any of the resources
+   * already exists, it will be overwritten.
+   *
+   * @param <R> The resource type
+   * @return the logical IDs of the newly created resources.
+   */
+  suspend fun <R : Resource> insertLocalOnly(vararg resource: R): List<String>
+
   /**
    * Inserts a list of remote `resources` into the FHIR resource database. If any of the resources
    * already exists, it will be overwritten.

engine/src/main/java/com/google/android/fhir/db/impl/DatabaseImpl.kt

@@ -47,6 +47,7 @@ import kotlinx.coroutines.Dispatchers
 import org.hl7.fhir.r4.model.IdType
 import org.hl7.fhir.r4.model.Resource
 import org.hl7.fhir.r4.model.ResourceType
+import java.util.Collections
 
 /**
  * The implementation for the persistence layer using Room. See docs for
@@ -140,6 +141,10 @@ internal class DatabaseImpl(
     return logicalIds
   }
 
+  override suspend fun <R : Resource> insertLocalOnly(vararg resource: R): List<String> {
+    return db.withTransaction { resourceDao.insertAllRemote(resource.toList()).map { it.toString() }.toList() }
+  }
+
   override suspend fun <R : Resource> insertRemote(vararg resource: R) {
     db.withTransaction { resourceDao.insertAllRemote(resource.toList()) }
   }

engine/src/main/java/com/google/android/fhir/impl/FhirEngineImpl.kt

@@ -46,8 +46,9 @@ import org.hl7.fhir.r4.model.ResourceType
 /** Implementation of [FhirEngine]. */
 internal class FhirEngineImpl(private val database: Database, private val context: Context) :
   FhirEngine {
-  override suspend fun create(vararg resource: Resource) =
-    withContext(Dispatchers.IO) { database.insert(*resource) }
+  override suspend fun create(vararg resource: Resource, isLocalOnly: Boolean): List<String> {
+    return withContext(Dispatchers.IO) { if (isLocalOnly) database.insertLocalOnly(*resource) else database.insert(*resource) }
+  }
 
   override suspend fun get(type: ResourceType, id: String) =
     withContext(Dispatchers.IO) { database.select(type, id) }

engine/src/main/java/com/google/android/fhir/testing/Utilities.kt

@@ -141,9 +141,9 @@ internal open class TestDownloadManagerImpl(
     return listOf(patient)
   }
 }
-
+ 
 internal object TestFhirEngineImpl : FhirEngine {
-  override suspend fun create(vararg resource: Resource) = emptyList<String>()
+  override suspend fun create(vararg resource: Resource, isLocalOnly: Boolean) = emptyList<String>()
 
   override suspend fun update(vararg resource: Resource) {}
 

engine/src/test/java/com/google/android/fhir/impl/FhirEngineImplTest.kt

@@ -94,6 +94,31 @@ class FhirEngineImplTest {
     assertResourceEquals(TEST_PATIENT_2, fhirEngine.get<Patient>(TEST_PATIENT_2_ID))
   }
 
+  @Test
+  fun create_isLocalOnlyTrue_shouldCreateResourceWithoutFlaggingLocalChange() = runBlocking {
+    val totalLocalChangesPatient2 =
+      fhirEngine.getLocalChanges(ResourceType.Patient, TEST_PATIENT_2_ID).size
+    fhirEngine.create(TEST_PATIENT_2, isLocalOnly = true)
+    assertResourceEquals(TEST_PATIENT_2, fhirEngine.get<Patient>(TEST_PATIENT_2_ID))
+    assertThat(fhirEngine.getLocalChanges(ResourceType.Patient, TEST_PATIENT_2_ID).size)
+      .isEqualTo(totalLocalChangesPatient2)
+  }
+
+  @Test
+  fun createAll_isLocalOnlyTrue_shouldCreateResourceWithoutFlaggingLocalChange() = runBlocking {
+    val totalLocalChangesPatient1 =
+      fhirEngine.getLocalChanges(ResourceType.Patient, TEST_PATIENT_1_ID).size
+    val totalLocalChangesPatient2 =
+      fhirEngine.getLocalChanges(ResourceType.Patient, TEST_PATIENT_2_ID).size
+    fhirEngine.create(TEST_PATIENT_1, TEST_PATIENT_2, isLocalOnly = true)
+    assertResourceEquals(TEST_PATIENT_1, fhirEngine.get<Patient>(TEST_PATIENT_1_ID))
+    assertResourceEquals(TEST_PATIENT_2, fhirEngine.get<Patient>(TEST_PATIENT_2_ID))
+    assertThat(fhirEngine.getLocalChanges(ResourceType.Patient, TEST_PATIENT_1_ID).size)
+      .isEqualTo(totalLocalChangesPatient1)
+    assertThat(fhirEngine.getLocalChanges(ResourceType.Patient, TEST_PATIENT_2_ID).size)
+      .isEqualTo(totalLocalChangesPatient2)
+  }
+
   @Test
   fun create_resourceWithoutId_shouldCreateResourceWithAssignedId() = runBlocking {
     val patient =