Adds a unit test for the interface adherence

src/plugins/data/public/search/errors/es_error.test.tsx

@@ -0,0 +1,40 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you 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.
+ */
+
+import { EsError } from './es_error';
+import { IEsError } from './types';
+
+describe('EsError', () => {
+  it('contains the same body as the wrapped error', () => {
+    const error = {
+      body: {
+        attributes: {
+          error: {
+            type: 'top_level_exception_type',
+            reason: 'top-level reason',
+          },
+        },
+      },
+    } as IEsError;
+    const esError = new EsError(error);
+
+    expect(typeof esError.body).toEqual('object');
+    expect(esError.body).toEqual(error.body);
+  });
+});