Add OpenTofu provider OCI artifact integration test

src/main/java/land/oras/Index.java

@@ -230,6 +230,16 @@ public Subject getSubject() {
         return subject;
     }
 
+    /**
+     * Return a new index with the given artifact type
+     * @param artifactType The artifact type
+     * @return The index
+     */
+    public Index withArtifactType(String artifactType) {
+        return new Index(
+                schemaVersion, mediaType, artifactType, manifests, annotations, subject, descriptor, registry, json);
+    }
+
     /**
      * Return a new index with the given subject
      * @param subject The subject

src/test/java/land/oras/IndexTest.java

@@ -147,6 +147,17 @@ void shouldAddManifests() {
         assertNull(notFound);
     }
 
+    @Test
+    void shouldAddArtifactType() {
+        Index index = Index.fromManifests(List.of());
+        index = index.withArtifactType("application/vnd.opentofu.provider");
+        assertNotNull(index.getArtifactType());
+        assertEquals("application/vnd.opentofu.provider", index.getArtifactType().getMediaType());
+        assertEquals(
+                "{\"schemaVersion\":2,\"mediaType\":\"application/vnd.oci.image.index.v1+json\",\"artifactType\":\"application/vnd.opentofu.provider\",\"manifests\":[]}",
+                index.toJson());
+    }
+
     @Test
     void shouldAddSubject() {
         Index index = Index.fromManifests(List.of());

src/test/java/land/oras/OpenTofuITCase.java

@@ -0,0 +1,93 @@
+/*-
+ * =LICENSE=
+ * ORAS Java SDK
+ * ===
+ * Copyright (C) 2024 - 2026 ORAS
+ * ===
+ * 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.
+ * =LICENSEEND=
+ */
+
+package land.oras;
+
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.List;
+import land.oras.utils.ZotUnsecureContainer;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.parallel.Execution;
+import org.junit.jupiter.api.parallel.ExecutionMode;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
+
+@Testcontainers
+@Execution(ExecutionMode.CONCURRENT)
+class OpenTofuITCase {
+
+    @Container
+    private final ZotUnsecureContainer unsecureRegistry = new ZotUnsecureContainer().withStartupAttempts(3);
+
+    /**
+     * This test demonstrates how to assemble an OpenTofu provider OCI artifact.
+     * See https://opentofu.org/docs/cli/oci_registries/provider-mirror/ for the specification.
+     */
+    @Test
+    void shouldAssembleOpenTofuProviderArtifact() {
+
+        // The provider zip archive for linux/amd64
+        Path providerZip = Paths.get("src/test/resources/archives")
+                .resolve("terraform-provider-aws_5.0.0_linux_amd64.zip");
+        String artifactType = "application/vnd.opentofu.provider";
+        String contentMediaType = "application/zip";
+
+        // Create objects for the linux/amd64 platform manifest
+        // The artifact type identifies the manifest as an OpenTofu provider; config is left empty
+        Config config = Config.empty();
+        Layer layer = Layer.fromFile(providerZip).withMediaType(contentMediaType);
+        Manifest manifest = Manifest.empty()
+                .withArtifactType(ArtifactType.from(artifactType))
+                .withConfig(config)
+                .withLayers(List.of(layer));
+
+        // Push config, layer and manifest to registry
+        Registry registry = Registry.builder()
+                .insecure()
+                .withRegistry(unsecureRegistry.getRegistry())
+                .build();
+
+        // The manifest is pushed without a version tag; the index will be tagged
+        ContainerRef manifestRef = ContainerRef.parse("terraform-provider-aws:5.0.0-linux-amd64");
+        registry.pushConfig(manifestRef, config);
+        registry.pushBlob(manifestRef, providerZip);
+        Manifest pushedManifest = registry.pushManifest(manifestRef, manifest);
+
+        // Ensure the manifest was pushed successfully
+        assertNotNull(pushedManifest);
+
+        // Build the index with the manifest descriptor, annotated with the linux/amd64 platform
+        // The index artifact type also identifies the whole provider release as an OpenTofu provider
+        ManifestDescriptor manifestDescriptor =
+                pushedManifest.getDescriptor().withPlatform(Platform.linuxAmd64());
+        Index index = Index.fromManifests(List.of(manifestDescriptor)).withArtifactType(artifactType);
+
+        // Push the index with the provider version tag
+        ContainerRef indexRef = ContainerRef.parse("terraform-provider-aws:5.0.0");
+        Index pushedIndex = registry.pushIndex(indexRef, index);
+
+        // Ensure the index was pushed and contains the linux/amd64 manifest
+        assertNotNull(pushedIndex);
+        assertNotNull(pushedIndex.findUnique(Platform.linuxAmd64()));
+    }
+}