Implement Room Database Entity for Todo Items

.gitignore

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+# Android
+*.iml
+.gradle
+/local.properties
+/.idea/
+.DS_Store
+/build
+/captures
+.externalNativeBuild
+.cxx
+
+# Kotlin
+*.class
+*.log
+
+# Dependency directories
+/node_modules/
+/app/build/
+
+# Sensitive files
+*.env
+*.key
+
+# Logs
+*.log
+
+# Test coverage
+/coverage/

app/src/main/java/com/todoapp/data/entity/TodoEntity.kt

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+package com.todoapp.data.entity
+
+import androidx.room.ColumnInfo
+import androidx.room.Entity
+import androidx.room.PrimaryKey
+import java.time.LocalDateTime
+
+/**
+ * Represents a Todo item in the Room database.
+ * Defines the schema for storing todo items with their properties.
+ *
+ * @property id Unique identifier for the todo item
+ * @property title Title of the todo item
+ * @property description Optional description of the todo item
+ * @property isCompleted Flag indicating whether the todo item is completed
+ * @property createdAt Timestamp of when the todo item was created
+ * @property dueDate Optional due date for the todo item
+ */
+@Entity(tableName = "todos")
+data class TodoEntity(
+    @PrimaryKey(autoGenerate = true)
+    @ColumnInfo(name = "id")
+    val id: Long = 0,
+
+    @ColumnInfo(name = "title")
+    val title: String,
+
+    @ColumnInfo(name = "description")
+    val description: String? = null,
+
+    @ColumnInfo(name = "is_completed")
+    val isCompleted: Boolean = false,
+
+    @ColumnInfo(name = "created_at")
+    val createdAt: LocalDateTime = LocalDateTime.now(),
+
+    @ColumnInfo(name = "due_date")
+    val dueDate: LocalDateTime? = null
+) {
+    // Validate title is not blank during object creation
+    init {
+        require(title.isNotBlank()) { "Todo title cannot be blank" }
+    }
+}

app/src/test/java/com/todoapp/data/entity/TodoEntityTest.kt

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+package com.todoapp.data.entity
+
+import org.junit.Assert.*
+import org.junit.Test
+import java.time.LocalDateTime
+
+class TodoEntityTest {
+
+    @Test
+    fun `create todo item with valid title`() {
+        val todo = TodoEntity(title = "Test Todo")
+
+        assertEquals("Test Todo", todo.title)
+        assertFalse(todo.isCompleted)
+        assertNotNull(todo.createdAt)
+    }
+
+    @Test
+    fun `create todo item with full details`() {
+        val dueDate = LocalDateTime.now().plusDays(1)
+        val todo = TodoEntity(
+            title = "Complete Project",
+            description = "Finish Android Todo App",
+            isCompleted = false,
+            dueDate = dueDate
+        )
+
+        assertEquals("Complete Project", todo.title)
+        assertEquals("Finish Android Todo App", todo.description)
+        assertFalse(todo.isCompleted)
+        assertEquals(dueDate, todo.dueDate)
+    }
+
+    @Test(expected = IllegalArgumentException::class)
+    fun `create todo item with blank title should throw exception`() {
+        TodoEntity(title = "")
+    }
+
+    @Test(expected = IllegalArgumentException::class)
+    fun `create todo item with whitespace title should throw exception`() {
+        TodoEntity(title = "   ")
+    }
+}

build.gradle.kts

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+// Placeholder for dependencies
+// In a real project, you would add Room, Kotlin, and testing dependencies here
+dependencies {
+    // Room Database
+    implementation("androidx.room:room-runtime:2.4.3")
+    implementation("androidx.room:room-ktx:2.4.3")
+    kapt("androidx.room:room-compiler:2.4.3")
+
+    // Testing
+    testImplementation("junit:junit:4.13.2")
+    testImplementation("androidx.arch.core:core-testing:2.1.0")
+    androidTestImplementation("androidx.test.ext:junit:1.1.3")
+}