[TEST] backport InternalAggregationTestCase

Note that it only extends ESTestCase, it will be used for fromXContent tests only in 5.x

This is a partial backport of elastic#22668

core/src/test/java/org/elasticsearch/search/aggregations/InternalAggregationTestCase.java

@@ -0,0 +1,45 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch 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.
+ */
+
+package org.elasticsearch.search.aggregations;
+
+import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
+import org.elasticsearch.test.ESTestCase;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public abstract class InternalAggregationTestCase<T extends InternalAggregation> extends ESTestCase {
+
+    protected abstract T createTestInstance(String name, List<PipelineAggregator> pipelineAggregators, Map<String, Object> metaData);
+
+    protected final T createTestInstance() {
+        String name = randomAlphaOfLength(5);
+        List<PipelineAggregator> pipelineAggregators = new ArrayList<>();
+        // TODO populate pipelineAggregators
+        Map<String, Object> metaData = new HashMap<>();
+        int metaDataCount = randomBoolean() ? 0 : between(1, 10);
+        while (metaData.size() < metaDataCount) {
+            metaData.put(randomAlphaOfLength(5), randomAlphaOfLength(5));
+        }
+        return createTestInstance(name, pipelineAggregators, metaData);
+    }
+}

core/src/test/java/org/elasticsearch/search/aggregations/metrics/InternalMaxTests.java

@@ -0,0 +1,38 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch 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.
+ */
+
+package org.elasticsearch.search.aggregations.metrics;
+
+import org.elasticsearch.search.DocValueFormat;
+import org.elasticsearch.search.aggregations.InternalAggregationTestCase;
+import org.elasticsearch.search.aggregations.metrics.max.InternalMax;
+import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
+
+import java.util.List;
+import java.util.Map;
+
+public class InternalMaxTests extends InternalAggregationTestCase<InternalMax> {
+
+    @Override
+    protected InternalMax createTestInstance(String name, List<PipelineAggregator> pipelineAggregators, Map<String, Object> metaData) {
+        return new InternalMax(name, randomDouble(),
+                randomFrom(DocValueFormat.BOOLEAN, DocValueFormat.GEOHASH, DocValueFormat.IP, DocValueFormat.RAW), pipelineAggregators,
+                metaData);
+    }
+}

core/src/test/java/org/elasticsearch/search/aggregations/metrics/min/InternalMinTests.java

@@ -0,0 +1,36 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch 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.
+ */
+
+package org.elasticsearch.search.aggregations.metrics.min;
+
+import org.elasticsearch.search.DocValueFormat;
+import org.elasticsearch.search.aggregations.InternalAggregationTestCase;
+import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
+
+import java.util.List;
+import java.util.Map;
+
+public class InternalMinTests extends InternalAggregationTestCase<InternalMin> {
+    @Override
+    protected InternalMin createTestInstance(String name, List<PipelineAggregator> pipelineAggregators, Map<String, Object> metaData) {
+        return new InternalMin(name, randomDouble(),
+                randomFrom(DocValueFormat.BOOLEAN, DocValueFormat.GEOHASH, DocValueFormat.IP, DocValueFormat.RAW), pipelineAggregators,
+                metaData);
+    }
+}