Adding more unit test coverage (#295)

* Adding tests for ExtensionRestHandler

Signed-off-by: Sarat Vemulapalli <vemulapallisarat@gmail.com>

* Adding unit tests for some more coverage

Signed-off-by: Sarat Vemulapalli <vemulapallisarat@gmail.com>

* Addressing comments

Signed-off-by: Sarat Vemulapalli <vemulapallisarat@gmail.com>

Signed-off-by: Sarat Vemulapalli <vemulapallisarat@gmail.com>

src/main/java/org/opensearch/sdk/BaseExtension.java

@@ -47,20 +47,22 @@ public abstract class BaseExtension implements Extension {
 
     /**
      * Instantiate this extension, initializing the connection settings and REST actions.
+     * @param path to extensions configuration.
      */
     protected BaseExtension(String path) {
         try {
             this.settings = ExtensionSettings.readSettingsFromYaml(path);
             if (settings == null || settings.getHostAddress() == null || settings.getHostPort() == null) {
                 throw new IOException("Failed to initialize Extension settings. No port bound.");
             }
-        } catch (IOException e) {
-            throw new ExceptionInInitializerError(e);
+        } catch (Exception e) {
+            throw new IllegalArgumentException(e);
         }
     }
 
     /**
-     * take an ExtensionSettings object and set it directly
+     * take an ExtensionSettings object and set it directly.
+     * @param settings defined by the extension.
      */
     protected BaseExtension(ExtensionSettings settings) {
         this.settings = settings;

src/main/java/org/opensearch/sdk/Extension.java

@@ -42,7 +42,9 @@ public interface Extension {
      *
      * @return a list of REST handlers (REST actions) this extension handles.
      */
-    List<ExtensionRestHandler> getExtensionRestHandlers();
+    default List<ExtensionRestHandler> getExtensionRestHandlers() {
+        return Collections.emptyList();
+    }
 
     /**
      * Gets an optional list of custom {@link Setting} for the extension to register with OpenSearch.

src/test/java/org/opensearch/sdk/TestBaseExtension.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.sdk;
+
+import org.junit.jupiter.api.Test;
+import org.opensearch.test.OpenSearchTestCase;
+
+/*
+ * Most of the code in BaseExtension is tested by HelloWorld extension tests.
+ * This class tests code paths which are not tested.
+ */
+public class TestBaseExtension extends OpenSearchTestCase {
+
+    private static final String UNPARSEABLE_EXTENSION_CONFIG = "/bad-extension.yml";
+    private static final String EXTENSION_DESCRIPTOR_FILEPATH = "src/test/resources" + UNPARSEABLE_EXTENSION_CONFIG;
+
+    public class TestExtension extends BaseExtension {
+
+        public TestExtension(String path) {
+            super(path);
+        }
+    }
+
+    @Test
+    public void testBaseExtensionWithNullPath() {
+        // When a null path is passed, reading from YAML will fail.
+        assertThrows(IllegalArgumentException.class, () -> { TestExtension testExtension = new TestExtension(null); });
+    }
+
+    @Test
+    public void testBaseExtensionWithBadConfig() {
+        // When a bad extensions.yml config is passed, expect failing initialization.
+        assertThrows(
+            IllegalArgumentException.class,
+            () -> { TestExtension testExtension = new TestExtension(EXTENSION_DESCRIPTOR_FILEPATH); }
+        );
+    }
+}

src/test/java/org/opensearch/sdk/TestExtensionRestHandler.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.sdk;
+
+import org.junit.jupiter.api.Test;
+import org.opensearch.extensions.rest.ExtensionRestRequest;
+import org.opensearch.extensions.rest.ExtensionRestResponse;
+import org.opensearch.test.OpenSearchTestCase;
+
+public class TestExtensionRestHandler extends OpenSearchTestCase {
+    private class NoOpExtensionRestHandler implements ExtensionRestHandler {
+
+        @Override
+        public ExtensionRestResponse handleRequest(ExtensionRestRequest request) {
+            return null;
+        }
+    }
+
+    @Test
+    public void testHandlerDefaultRoutes() {
+        NoOpExtensionRestHandler handler = new NoOpExtensionRestHandler();
+        assertTrue(handler.routes().isEmpty());
+    }
+}

src/test/resources/bad-extension.yml

@@ -0,0 +1 @@
+extensionName: bad-extension