Refactor ContainerResourceTest to use parameterized tests

Several test cases in `ContainerResourceTest` have the same outcome,
so instead of duplicating the assertions inside each test method, take
advantage of `@ParameterizedTest` to inject inputs and expected
outputs multiple times into the same test. This improves test code
readability by reducing test method length and making identical cases
more obvious.

Also rename test methods to better express the tested code's expected
behaviour.

Issue-Id: open-telemetry#6694
Issue-Id: open-telemetry/opentelemetry-java#2337

instrumentation/resources/library/src/test/java/io/opentelemetry/instrumentation/resources/ContainerResourceTest.java

@@ -7,92 +7,82 @@
 
 import static io.opentelemetry.instrumentation.resources.ContainerResource.buildResource;
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.params.provider.Arguments.arguments;
 
 import io.opentelemetry.sdk.resources.Resource;
 import io.opentelemetry.semconv.resource.attributes.ResourceAttributes;
 import java.io.IOException;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.util.stream.Stream;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+import org.junit.jupiter.params.provider.ValueSource;
 
 class ContainerResourceTest {
 
-  @Test
-  void buildResource_Invalid(@TempDir Path tempFolder) throws IOException {
-    // invalid containerId (non-hex)
-    Path cgroup =
-        createCgroup(
-            tempFolder.resolve("cgroup1"),
-            "13:name=systemd:/podruntime/docker/kubepods/ac679f8a8319c8cf7d38e1adf263bc08d23zzzz");
-    assertThat(buildResource(cgroup)).isEqualTo(Resource.empty());
-
-    // unrecognized format (last "-" is after last ".")
-    cgroup =
-        createCgroup(
-            tempFolder.resolve("cgroup1"),
-            "13:name=systemd:/podruntime/docker/kubepods/ac679f8.a8319c8cf7d38e1adf263bc08-d23zzzz");
-    assertThat(buildResource(cgroup)).isEqualTo(Resource.empty());
-
-    // test invalid file
-    cgroup = tempFolder.resolve("DoesNotExist");
+  @ParameterizedTest
+  @ValueSource(
+      strings = {
+        // invalid containerId (non-hex)
+        "13:name=systemd:/podruntime/docker/kubepods/ac679f8a8319c8cf7d38e1adf263bc08d23zzzz",
+        // unrecognized format (last "-" is after last ".")
+        "13:name=systemd:/podruntime/docker/kubepods/ac679f8.a8319c8cf7d38e1adf263bc08-d23zzzz"
+      })
+  void buildResource_returnsEmptyResource_whenContainerIdIsInvalid(
+      String line, @TempDir Path tempFolder) throws IOException {
+    Path cgroup = createCgroup(tempFolder.resolve("cgroup"), line);
     assertThat(buildResource(cgroup)).isEqualTo(Resource.empty());
   }
 
   @Test
-  void buildResource_Valid(@TempDir Path tempFolder) throws IOException {
-    // with suffix
-    Path cgroup =
-        createCgroup(
-            tempFolder.resolve("cgroup1"),
-            "13:name=systemd:/podruntime/docker/kubepods/ac679f8a8319c8cf7d38e1adf263bc08d23.aaaa");
-    assertThat(getContainerId(buildResource(cgroup)))
-        .isEqualTo("ac679f8a8319c8cf7d38e1adf263bc08d23");
-
-    // with prefix and suffix
-    Path cgroup2 =
-        createCgroup(
-            tempFolder.resolve("cgroup2"),
-            "13:name=systemd:/podruntime/docker/kubepods/crio-dc679f8a8319c8cf7d38e1adf263bc08d23.stuff");
-    assertThat(getContainerId(buildResource(cgroup2)))
-        .isEqualTo("dc679f8a8319c8cf7d38e1adf263bc08d23");
+  void buildResource_returnsEmptyResource_whenFileDoesNotExist(@TempDir Path tempFolder) {
+    Path cgroup = tempFolder.resolve("DoesNotExist");
+    assertThat(buildResource(cgroup)).isEqualTo(Resource.empty());
+  }
 
-    // just container id
-    Path cgroup3 =
-        createCgroup(
-            tempFolder.resolve("cgroup3"),
-            "13:name=systemd:/pod/d86d75589bf6cc254f3e2cc29debdf85dde404998aa128997a819ff991827356");
-    assertThat(getContainerId(buildResource(cgroup3)))
-        .isEqualTo("d86d75589bf6cc254f3e2cc29debdf85dde404998aa128997a819ff991827356");
+  @ParameterizedTest
+  @MethodSource
+  void buildResource_extractsContainerIdFromValidLines(
+      String line, String expectedContainerId, @TempDir Path tempFolder) throws IOException {
+    Path cgroup = createCgroup(tempFolder.resolve("cgroup"), line);
+    assertThat(getContainerId(buildResource(cgroup))).isEqualTo(expectedContainerId);
+  }
 
-    // with prefix
-    Path cgroup4 =
-        createCgroup(
-            tempFolder.resolve("cgroup4"),
+  static Stream<Arguments> buildResource_extractsContainerIdFromValidLines() {
+    return Stream.of(
+        // with suffix
+        arguments(
+            "13:name=systemd:/podruntime/docker/kubepods/ac679f8a8319c8cf7d38e1adf263bc08d23.aaaa",
+            "ac679f8a8319c8cf7d38e1adf263bc08d23"),
+        // with prefix and suffix
+        arguments(
+            "13:name=systemd:/podruntime/docker/kubepods/crio-dc679f8a8319c8cf7d38e1adf263bc08d23.stuff",
+            "dc679f8a8319c8cf7d38e1adf263bc08d23"),
+        // just container id
+        arguments(
+            "13:name=systemd:/pod/d86d75589bf6cc254f3e2cc29debdf85dde404998aa128997a819ff991827356",
+            "d86d75589bf6cc254f3e2cc29debdf85dde404998aa128997a819ff991827356"),
+        // with prefix
+        arguments(
             "//\n"
                 + "1:name=systemd:/podruntime/docker/kubepods/docker-dc579f8a8319c8cf7d38e1adf263bc08d23"
                 + "2:name=systemd:/podruntime/docker/kubepods/docker-dc579f8a8319c8cf7d38e1adf263bc08d23"
-                + "3:name=systemd:/podruntime/docker/kubepods/docker-dc579f8a8319c8cf7d38e1adf263bc08d23");
-    assertThat(getContainerId(buildResource(cgroup4)))
-        .isEqualTo("dc579f8a8319c8cf7d38e1adf263bc08d23");
-
-    // with two dashes in prefix
-    Path cgroup5 =
-        createCgroup(
-            tempFolder.resolve("cgroup5"),
-            "11:perf_event:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod4415fd05_2c0f_4533_909b_f2180dca8d7c.slice/cri-containerd-713a77a26fe2a38ebebd5709604a048c3d380db1eb16aa43aca0b2499e54733c.scope");
-    assertThat(getContainerId(buildResource(cgroup5)))
-        .isEqualTo("713a77a26fe2a38ebebd5709604a048c3d380db1eb16aa43aca0b2499e54733c");
-
-    // with colon, env: k8s v1.24.0, the cgroupDriver by systemd(default), and container is
-    // cri-containerd v1.6.8
-    Path cgroup6 =
-        createCgroup(
-            tempFolder.resolve("cgroup6"),
-            "11:devices:/system.slice/containerd.service/kubepods-pod87a18a64_b74a_454a_b10b_a4a36059d0a3.slice:cri-containerd:05c48c82caff3be3d7f1e896981dd410e81487538936914f32b624d168de9db0");
-    assertThat(getContainerId(buildResource(cgroup6)))
-        .isEqualTo("05c48c82caff3be3d7f1e896981dd410e81487538936914f32b624d168de9db0");
+                + "3:name=systemd:/podruntime/docker/kubepods/docker-dc579f8a8319c8cf7d38e1adf263bc08d23",
+            "dc579f8a8319c8cf7d38e1adf263bc08d23"),
+        // with two dashes in prefix
+        arguments(
+            "11:perf_event:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod4415fd05_2c0f_4533_909b_f2180dca8d7c.slice/cri-containerd-713a77a26fe2a38ebebd5709604a048c3d380db1eb16aa43aca0b2499e54733c.scope",
+            "713a77a26fe2a38ebebd5709604a048c3d380db1eb16aa43aca0b2499e54733c"),
+        // with colon, env: k8s v1.24.0, the cgroupDriver by systemd(default), and container is
+        // cri-containerd v1.6.8
+        arguments(
+            "11:devices:/system.slice/containerd.service/kubepods-pod87a18a64_b74a_454a_b10b_a4a36059d0a3.slice:cri-containerd:05c48c82caff3be3d7f1e896981dd410e81487538936914f32b624d168de9db0",
+            "05c48c82caff3be3d7f1e896981dd410e81487538936914f32b624d168de9db0"));
   }
 
   private static String getContainerId(Resource resource) {