Add test of migration by means of test-containers

Note that this is just a proof-of-concept that requires
more refactoring. For instance, it tests the migration classes,
but rather should test the DbMigration class. The latter
needs to be refactored to some degree so that the test class
can inject the spawned test container configuration.

build.gradle

@@ -20,7 +20,17 @@ dependencies {
   implementation 'com.github.mongobee:mongobee:0.13'
   implementation 'com.typesafe:config:1.3.1'
   implementation 'com.github.sdkman:sdkman-url-validator:0.2.5'
+
+  testImplementation 'org.junit.jupiter:junit-jupiter:5.10.0'
+  testImplementation 'org.testcontainers:junit-jupiter:1.19.0'
+  testImplementation 'org.testcontainers:mongodb:1.19.0'
+  testImplementation 'javax.xml.bind:jaxb-api:2.3.1' // Provides the javax.xml.bind package (including DatatypeConverter)
+
   runtimeOnly 'org.slf4j:slf4j-simple:1.7.25'
 }
 
 compileScala.dependsOn("checkScalafmt")
+
+tasks.test {
+  useJUnitPlatform()
+}

src/test/java/io/sdkman/DbMigrationTest.java

@@ -0,0 +1,73 @@
+package io.sdkman;
+
+import com.github.mongobee.Mongobee;
+import com.mongodb.MongoClient;
+import com.mongodb.MongoClientURI;
+import com.mongodb.client.MongoDatabase;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestInstance;
+import org.testcontainers.containers.MongoDBContainer;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+@TestInstance(TestInstance.Lifecycle.PER_CLASS)
+class DbMigrationTest {
+
+    private static final String DB_NAME = "sdkman";
+    private MongoDBContainer mongoContainer;
+    private MongoClient mongoClient;
+
+    @BeforeAll
+    void setUp() {
+        // Start a Testcontainers MongoDB instance
+        // Apple Silicon requires a minimum version of 5,
+        // though in prod there seems to be a version 3.2 running.
+        mongoContainer = new MongoDBContainer("mongo:5.0");
+        mongoContainer.start();
+    }
+
+    @AfterAll
+    void tearDown() {
+        if (mongoContainer != null) mongoContainer.stop();
+    }
+
+    @BeforeEach
+    void initializeMongoClient() {
+        // Create a MongoClient connected to the container
+        MongoClientURI uri = new MongoClientURI(mongoContainer.getConnectionString());
+        mongoClient = new MongoClient(uri);
+    }
+
+    @AfterEach
+    void closeMongoClient() {
+        if (mongoClient != null) mongoClient.close();
+    }
+
+    @Test
+    void testDbMigration() {
+        try {
+            // Configure Mongobee to use the Testcontainers MongoDB
+            // Note, testing DbMigration class directly would require slight refactoring to inject test container
+            Mongobee mongobee = new Mongobee(mongoContainer.getConnectionString());
+            mongobee.setDbName(DB_NAME); // Set the database name
+            mongobee.setChangeLogsScanPackage("io.sdkman.changelogs");
+            mongobee.execute(); // Execute the migration
+
+            // Verify the migration by checking an expected collection or data
+            MongoDatabase database = mongoClient.getDatabase(DB_NAME);
+
+            boolean collectionExists =
+                    database.listCollectionNames().into(new java.util.ArrayList<>()).contains("candidates");
+            assertTrue(collectionExists, "Expected collection does not exist after migration!");
+
+            // Add more verifications as needed (e.g., checking documents, indexes, etc.)
+        } catch (Exception e) {
+            Assertions.fail("Migration failed: " + e.getMessage());
+        }
+    }
+}