JUnit5 migration

.mvn/wrapper/maven-wrapper.properties

@@ -1,2 +1,18 @@
-distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.8.1/apache-maven-3.8.1-bin.zip
-wrapperUrl=https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar
+# 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.
+distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.9.5/apache-maven-3.9.5-bin.zip
+wrapperUrl=https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/3.2.0/maven-wrapper-3.2.0.jar

examples/example-exporter-opentelemetry/src/main/java/io/prometheus/metrics/examples/opentelemetry/ManualCompleteMetricsTest.java

@@ -17,7 +17,7 @@
 import java.util.Random;
 */
 
-public class ManualCompleteMetricsTest {
+class ManualCompleteMetricsTest {
 
     // This contains a complete set of all metric types, and target_info and otel_scope_info.
     // I used this to expose in Prometheus format and OTLP format at the same time and compare the results.

integration-tests/it-common/pom.xml

@@ -30,6 +30,11 @@
             <artifactId>testcontainers</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>

integration-tests/it-common/src/test/java/io/prometheus/client/it/common/Volume.java

@@ -1,6 +1,6 @@
 package io.prometheus.client.it.common;
 
-import org.junit.Assert;
+import org.junit.jupiter.api.Assertions;
 
 import java.io.File;
 import java.io.IOException;
@@ -24,7 +24,7 @@ private Volume(Path tmpDir) {
 
     public static Volume create(String prefix) throws IOException, URISyntaxException {
         Path targetDir = Paths.get(Volume.class.getResource("/").toURI()).getParent();
-        Assert.assertEquals("failed to locate target/ directory", "target", targetDir.getFileName().toString());
+        Assertions.assertEquals("target", targetDir.getFileName().toString(), "failed to locate target/ directory");
         return new Volume(Files.createTempDirectory(targetDir, prefix + "-"));
     }
 
@@ -56,7 +56,7 @@ public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IO
                 }
             });
         } else {
-            Assert.fail(src + ": No such file or directory");
+            Assertions.fail(src + ": No such file or directory");
         }
         return this;
     }

integration-tests/it-exporter/it-exporter-test/pom.xml

@@ -37,10 +37,16 @@
             <artifactId>prometheus-metrics-exposition-formats</artifactId>
             <version>${project.version}</version>
         </dependency>
+
+        <!-- test dependencies -->
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
-            <groupId>junit</groupId>
-            <artifactId>junit</artifactId>
-            <version>4.13.2</version>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-params</artifactId>
             <scope>test</scope>
         </dependency>
         <dependency>