Add a test (open-telemetry#48)

Co-authored-by: Lauri Tulmin <[email protected]>

Author: trask

build.gradle.kts

@@ -44,6 +44,9 @@ dependencies {
   compileOnly("io.grpc:grpc-api:$grpcVersion")
   compileOnly("io.grpc:grpc-protobuf:$grpcVersion")
   compileOnly("io.grpc:grpc-stub:$grpcVersion")
+
+  testImplementation("org.junit.jupiter:junit-jupiter:5.11.4")
+  testImplementation("org.assertj:assertj-core:3.27.3")
 }
 
 protobuf {
@@ -76,6 +79,10 @@ var protoVersion = if (properties.contains(
 val protoArchive = file("$buildDir/archives/opentelemetry-proto-$protoVersion.zip")
 
 tasks {
+  test {
+    useJUnitPlatform()
+  }
+
   val downloadProtoArchive by registering(Download::class) {
     onlyIf { !protoArchive.exists() }
     src("https://github.com/open-telemetry/opentelemetry-proto/archive/v$protoVersion.zip")

src/test/java/io/opentelemetry/proto/AvailabilityTest.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.proto;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.fail;
+
+import java.lang.reflect.Field;
+import org.junit.jupiter.api.Test;
+
+/** A placeholder test which verifies that the generated classes compile and can load. */
+public class AvailabilityTest {
+
+  @Test
+  void available() {
+    isValidClass("io.opentelemetry.proto.trace.v1.Span");
+    isValidClass("io.opentelemetry.proto.metrics.v1.Metric");
+    isValidClass("io.opentelemetry.proto.logs.v1.LogRecord");
+  }
+
+  private static void isValidClass(String fqcn) {
+    Class<?> clazz = null;
+    try {
+      clazz = Class.forName(fqcn);
+    } catch (ClassNotFoundException e) {
+      fail(e.getMessage());
+    }
+    Field[] declaredFields = clazz.getDeclaredFields();
+    Class<?>[] declaredClasses = clazz.getDeclaredClasses();
+    boolean hasFieldsOrInnerClasses =
+        (declaredFields != null && declaredFields.length > 0)
+            || (declaredClasses != null && declaredClasses.length > 0);
+    assertThat(hasFieldsOrInnerClasses).withFailMessage(() -> fqcn + " is empty").isTrue();
+  }
+}