Parallelize tests (except on CI)

This change enables JUnit 5's parallel mode. On my machine, this change
causes `./mvnw` to run in a third of the time (from 90 seconds to 30
seconds). Integration test time specifically has been reduced 80% (from
75 seconds to 15 seconds).

In order to prevent the introduction of reliability issues with CI
builds, parallel execution is disabled in our `maven.yml`.

Author: rschmitt

.github/workflows/maven.yml

@@ -49,4 +49,4 @@ jobs:
         distribution: 'temurin'
         java-version: ${{ matrix.java }}
     - name: Build with Maven
-      run: ./mvnw -V --file pom.xml --no-transfer-progress -DtrimStackTrace=false -P-use-toolchains,docker
+      run: ./mvnw -V --file pom.xml --no-transfer-progress -DtrimStackTrace=false -Djunit.jupiter.execution.parallel.enabled=false -P-use-toolchains,docker

httpcore5-h2/src/test/resources/junit-platform.properties

@@ -0,0 +1,22 @@
+#
+# 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.
+#
+junit.jupiter.execution.parallel.enabled = true
+junit.jupiter.execution.parallel.mode.default = concurrent
+junit.jupiter.execution.parallel.mode.classes.default = concurrent
+junit.jupiter.execution.parallel.config.strategy = dynamic

httpcore5-reactive/src/test/resources/junit-platform.properties

@@ -0,0 +1,22 @@
+#
+# 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.
+#
+junit.jupiter.execution.parallel.enabled = true
+junit.jupiter.execution.parallel.mode.default = concurrent
+junit.jupiter.execution.parallel.mode.classes.default = concurrent
+junit.jupiter.execution.parallel.config.strategy = dynamic

httpcore5-testing/src/test/resources/junit-platform.properties

@@ -0,0 +1,22 @@
+#
+# 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.
+#
+junit.jupiter.execution.parallel.enabled = true
+junit.jupiter.execution.parallel.mode.default = concurrent
+junit.jupiter.execution.parallel.mode.classes.default = concurrent
+junit.jupiter.execution.parallel.config.strategy = dynamic

httpcore5/src/test/java/org/apache/hc/core5/ssl/TestSSLContextBuilder.java

@@ -66,10 +66,12 @@
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.parallel.Isolated;
 
 /**
  * Unit tests for {@link SSLContextBuilder}.
  */
+@Isolated
 class TestSSLContextBuilder {
 
     static final String PROVIDER_SUN_JSSE = "SunJSSE";

httpcore5/src/test/resources/junit-platform.properties

@@ -0,0 +1,22 @@
+#
+# 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.
+#
+junit.jupiter.execution.parallel.enabled = true
+junit.jupiter.execution.parallel.mode.default = concurrent
+junit.jupiter.execution.parallel.mode.classes.default = concurrent
+junit.jupiter.execution.parallel.config.strategy = dynamic