Upgrade metrics exporter to use JUnit5

Author: psx95

exporters/metrics/build.gradle

@@ -27,12 +27,19 @@ dependencies {
 implementation(platform(libraries.opentelemetry_bom))
 implementation(project(':shared-resourcemapping'))
 implementation(libraries.opentelemetry_semconv)
-testImplementation(testLibraries.junit)
+testImplementation(testLibraries.junit5)
+testImplementation(testLibraries.junit5_params)
+testRuntimeOnly(testLibraries.junit5_runtime)
 testImplementation(testLibraries.mockito)
 testImplementation(testLibraries.slf4j_simple)
 testImplementation(testLibraries.test_containers)
 testImplementation(testLibraries.opentelemetry_sdk_testing)
 testImplementation(testLibraries.opencensus_shim)
 }
 
+test {
+// required for discovering JUnit 5 tests
+useJUnitPlatform()
+}
+
 test.dependsOn ':shared-resourcemapping:shadowJar'

exporters/metrics/src/test/java/com/google/cloud/opentelemetry/metric/MetricConfigurationTest.java

@@ -19,8 +19,8 @@
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertThrows;
 import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import com.google.auth.Credentials;
 import com.google.auth.oauth2.AccessToken;