[FLINK-36441] Show full stacktraces in tests for failures

Make assertj print full stacktraces when encountering unexpected exceptions.

Author: AHeise

flink-connector-kafka/src/test/java/org/apache/flink/KafkaAssertjConfiguration.java

@@ -0,0 +1,30 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF 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.apache.flink;
+
+import org.assertj.core.configuration.Configuration;
+
+/** Configuration for AssertJ that shows full stack traces for unmatched exceptions. */
+public class KafkaAssertjConfiguration extends Configuration {
+    public KafkaAssertjConfiguration() {
+        // in case of an assertion error, show the full stack trace
+        // for green builds, this is not changing anything
+        setMaxStackTraceElementsDisplayed(10000);
+    }
+}

flink-connector-kafka/src/test/resources/META-INF/services/org.assertj.core.configuration.Configuration

@@ -0,0 +1,19 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF 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.
+#
+
+org.apache.flink.KafkaAssertjConfiguration