Merge pull request #1160 from diegotorrespy/master

 KTLN-860: Unit tests

Author: maibin

kotlin-libraries-http/pom.xml

@@ -59,12 +59,18 @@
             <artifactId>gson</artifactId>
             <version>${gson.version}</version>
         </dependency>
+        <dependency>
+            <groupId>com.squareup.retrofit2</groupId>
+            <artifactId>retrofit</artifactId>
+            <version>${retrofit.version}</version>
+        </dependency>
     </dependencies>
 
     <properties>
         <khttp.version>1.3.1</khttp.version>
         <fuel.version>2.3.1</fuel.version>
         <http4k.version>5.25.0.0</http4k.version>
+        <retrofit.version>2.9.0</retrofit.version>
     </properties>
 
 </project>

kotlin-libraries-http/src/main/kotlin/com/baeldung/retrofit/FileDownloadService.kt

@@ -0,0 +1,38 @@
+package com.baeldung.retrofit
+
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+import okhttp3.ResponseBody
+import retrofit2.Retrofit
+import retrofit2.http.GET
+import retrofit2.http.Url
+import java.io.File
+import java.io.FileOutputStream
+
+// Retrofit service interface
+interface FileDownloadService {
+    @GET
+    suspend fun downloadFile(@Url fileUrl: String): ResponseBody
+}
+
+// Function to download a PDF using Retrofit
+suspend fun downloadPdfWithRetrofit(url: String, outputFile: File) {
+    val retrofit = Retrofit.Builder()
+        .baseUrl("https://example.com/") // Base URL is required but won't be used with dynamic @Url
+        .build()
+
+    val service = retrofit.create(FileDownloadService::class.java)
+
+    withContext(Dispatchers.IO) {
+        val responseBody = service.downloadFile(url)
+
+        // Save the file to disk
+        responseBody.byteStream().use { inputStream ->
+            FileOutputStream(outputFile).use { outputStream ->
+                inputStream.copyTo(outputStream)
+            }
+        }
+
+        println("File downloaded successfully to ${outputFile.absolutePath}")
+    }
+}

kotlin-libraries-http/src/test/kotlin/com/baeldung/retrofit/FileDownloadServiceUnitTest.kt

@@ -0,0 +1,28 @@
+package com.baeldung.retrofit
+
+import kotlinx.coroutines.runBlocking
+import org.junit.Test
+import java.io.File
+import kotlin.test.assertTrue
+
+class FileDownloadServiceUnitTest {
+
+    @Test
+    fun testSuccessfulFileDownload(): Unit = runBlocking {
+
+        // File to store the downloaded content
+        val outputFile = File("test_sample.pdf")
+        if (outputFile.exists()) {
+            outputFile.delete()
+        }
+
+        // Call the download function
+        downloadPdfWithRetrofit("https://www.w3.org/WAI/ER/tests/xhtml/testfiles/resources/pdf/dummy.pdf", outputFile)
+
+        // Verify the file was created
+        assertTrue(outputFile.exists())
+
+        // Clean up the test file
+        outputFile.delete()
+    }
+}