Linkage Checker to throw exception upon missing artifact

dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/LinkageChecker.java

@@ -20,6 +20,7 @@
 import static com.google.common.collect.ImmutableSet.toImmutableSet;
 
 import com.google.cloud.tools.opensource.dependencies.Bom;
+import com.google.cloud.tools.opensource.dependencies.UnresolvableArtifactProblem;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
@@ -110,6 +111,20 @@ public static LinkageChecker create(Bom bom, Path exclusionFile)
         classPathBuilder.resolve(managedDependencies, true, DependencyMediation.MAVEN);
     ImmutableList<ClassPathEntry> classpath = classPathResult.getClassPath();
 
+    ImmutableList<UnresolvableArtifactProblem> artifactProblems =
+        classPathResult.getArtifactProblems();
+    if (!artifactProblems.isEmpty()) {
+      for (UnresolvableArtifactProblem artifactProblem : artifactProblems) {
+        logger.severe(artifactProblem.toString());
+      }
+      throw new IOException(
+          "Could not resolve "
+              + (artifactProblems.size() == 1
+                  ? "1 dependency"
+                  : (artifactProblems.size() + " dependencies"))
+              + ". See the message above for details.");
+    }
+
     // When checking a BOM, entry point classes are the ones in the artifacts listed in the BOM
     List<ClassPathEntry> artifactsInBom = classpath.subList(0, managedDependencies.size());
     ImmutableSet<ClassPathEntry> entryPoints = ImmutableSet.copyOf(artifactsInBom);

dependencies/src/test/java/com/google/cloud/tools/opensource/classpath/LinkageCheckerTest.java

@@ -26,6 +26,7 @@
 import static org.junit.Assert.fail;
 
 import com.google.cloud.tools.opensource.dependencies.Artifacts;
+import com.google.cloud.tools.opensource.dependencies.Bom;
 import com.google.cloud.tools.opensource.dependencies.DependencyGraph;
 import com.google.cloud.tools.opensource.dependencies.DependencyGraphBuilder;
 import com.google.cloud.tools.opensource.dependencies.DependencyPath;
@@ -1247,4 +1248,27 @@ public void testFindLinkageProblems_shouldNotReportMethodHandleInvoke()
 
     Truth.assertThat(problemsOnMethodHandle).isEmpty();
   }
+
+  @Test
+  public void testBomResolutionWithMissingTransitiveDependency() throws Exception {
+    DefaultArtifact cglib = new DefaultArtifact("cglib:cglib-nodep:jar:2.2");
+    // cglib-nodep has 2 transitive dependencies, which do not exist in Maven Central
+    // cglib:cglib-nodep:jar:2.2
+    //   - ant:ant:jar:1.6.2 (compile?)
+    //     - xml-apis:xml-apis:jar:2.6.2 (compile?)
+    //     - xerces:xerces-impl:jar:2.6.2 (compile?)
+    // https://github.com/GoogleCloudPlatform/cloud-opensource-java/issues/2097
+    Bom bomWithMissingTransitiveDependency =
+        new Bom(
+            "com.google.cloud:bom-with-missing-transitive-dependency:0.1",
+            ImmutableList.of(cglib));
+    try {
+      LinkageChecker.create(bomWithMissingTransitiveDependency);
+      fail("Linkage Checker should throw IOException");
+    } catch (IOException expected) {
+      assertEquals(
+          "Could not resolve 2 dependencies. See the message above for details.",
+          expected.getMessage());
+    }
+  }
 }