feat(module/mongodb): Add support for initialization scripts

Running initialization scripts in MongoDB causes the container to restart, which previously required manual WaitStrategy adjustment.

This commit adds 'withInitScript(String)' to automatically handle the script copy and adjust the WaitStrategy to expect two startup log messages.

Fixes #3066

Author: taole33

modules/mongodb/src/main/java/org/testcontainers/containers/MongoDBContainer.java

@@ -223,4 +223,26 @@ void withSharding() {
             setEntrypoint("sh");
         }
     }
+
+    /**
+     * Executes a MongoDB initialization script from the classpath during startup.
+     * <p>
+     * The script will be copied to {@code /docker-entrypoint-initdb.d/init.js}.
+     * This method also adjusts the {@link org.testcontainers.containers.wait.strategy.WaitStrategy}
+     * to expect the "waiting for connections" log message twice, as the execution of an init script
+     * causes MongoDB to restart.
+     *
+     * @param scriptPath the path to the init script file on the classpath
+     * @return this container instance
+     */
+    public MongoDBContainer withInitScript(String scriptPath) {
+        withCopyFileToContainer(
+            MountableFile.forClasspathResource(scriptPath), 
+            "/docker-entrypoint-initdb.d/init.js"
+        );
+
+        this.waitStrategy = Wait.forLogMessage("(?i).*waiting for connections.*", 2);
+
+        return this;
+    }
 }

modules/mongodb/src/test/java/org/testcontainers/mongodb/MongoDBInitScriptTest.java

@@ -0,0 +1,27 @@
+package org.testcontainers.containers;
+
+import org.junit.jupiter.api.Test;
+import org.testcontainers.utility.MountableFile;
+
+import java.time.Duration;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class MongoDBInitScriptTest {
+
+    @Test
+    void testWithInitScript() {
+        // Start the container using try-with-resources to ensure it closes automatically
+        try (MongoDBContainer mongoDB = new MongoDBContainer("mongo:4.0.10")
+            // Configure the init script. This triggers a restart inside the container,
+            // so the container must wait for the second "waiting for connections" log message.
+            .withInitScript("init.js")
+            .withStartupTimeout(Duration.ofSeconds(30))) {
+
+            mongoDB.start();
+
+            // Assert that the container started successfully
+            assertThat(mongoDB.isRunning()).isTrue();
+        }
+    }
+}

modules/mongodb/src/test/resources/init.js

@@ -0,0 +1 @@
+db.createCollection("test_collection");