[#75] Fix: set default value for role in public Content class and b…

…uilder (#76)

# Summary

- Specify default value for `role` as a `"user"` in a public API class
Content.
- Added tests for the verification of conversion functions (_from public
class to internal class and vice versa_).

Fixes: #75

---------

Co-authored-by: Rodrigo Lazo <[email protected]>

generativeai/src/main/java/com/google/ai/client/generativeai/type/Content.kt

@@ -25,10 +25,10 @@ import android.graphics.Bitmap
  *
  * @see content
  */
-class Content @JvmOverloads constructor(val role: String? = null, val parts: List<Part>) {
+class Content @JvmOverloads constructor(val role: String? = "user", val parts: List<Part>) {
 
   class Builder {
-    var role: String? = null
+    var role: String? = "user"
 
     var parts: MutableList<Part> = arrayListOf()
 
@@ -56,7 +56,7 @@ class Content @JvmOverloads constructor(val role: String? = null, val parts: Lis
  * )
  * ```
  */
-fun content(role: String? = null, init: Content.Builder.() -> Unit): Content {
+fun content(role: String? = "user", init: Content.Builder.() -> Unit): Content {
   val builder = Content.Builder()
   builder.role = role
   builder.init()

generativeai/src/test/java/com/google/ai/client/generativeai/internal/util/ConversionsTest.kt

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2024 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.ai.client.generativeai.internal.util
+
+import com.google.ai.client.generativeai.internal.api.shared.Content
+import com.google.ai.client.generativeai.internal.api.shared.TextPart
+import com.google.ai.client.generativeai.type.content
+import io.kotest.matchers.shouldBe
+import org.junit.Test
+
+class ConversionsTest {
+
+  @Test
+  fun `test content conversion toInternal (role not mentioned)`() {
+    val content = content { text("test") }.toInternal()
+    content.run {
+      // default role should be a "user"
+      role shouldBe "user"
+
+      // only one part should be present
+      parts.size shouldBe 1
+      parts[0].run { (this as TextPart).text shouldBe "test" }
+    }
+  }
+
+  @Test
+  fun `test content conversion toInternal (role mentioned)`() {
+    val content = content(role = "model") { text("test") }.toInternal()
+    content.run {
+      // Role should be a "model"
+      role shouldBe "model"
+
+      // only one part should be present
+      parts.size shouldBe 1
+      parts[0].run { (this as TextPart).text shouldBe "test" }
+    }
+  }
+
+  @Test
+  fun `test content conversion toPublic (role not mentioned)`() {
+    val content = Content(parts = listOf(TextPart("test"))).toPublic()
+    content.role shouldBe "user"
+  }
+
+  @Test
+  fun `test content conversion toPublic (role mentioned)`() {
+    val content = Content(role = "model", parts = listOf(TextPart("test"))).toPublic()
+    content.role shouldBe "model"
+  }
+}