[Test] Reconcile TestProjectResolvers

This PR updates the different methods in TestProjectResolvers so that
their names are more accurate and behaviours to be more as expected.

Author: ywangd

test/framework/src/main/java/org/elasticsearch/cluster/project/TestProjectResolvers.java

@@ -16,6 +16,7 @@
 import org.elasticsearch.common.util.concurrent.ThreadContext;
 import org.elasticsearch.core.CheckedRunnable;
 import org.elasticsearch.tasks.Task;
+import org.elasticsearch.test.ESTestCase;
 
 import java.util.Collection;
 import java.util.Objects;
@@ -60,7 +61,7 @@ public boolean supportsMultipleProjects() {
      * with the executeOnProject method. This is mostly useful in places where we just need a placeholder to satisfy
      * the constructor signature.
      */
-    public static ProjectResolver singleProjectOnly() {
+    public static ProjectResolver mustExecuteFirst() {
         return new ProjectResolver() {
 
             private ProjectId enforceProjectId = null;
@@ -102,12 +103,25 @@ public boolean supportsMultipleProjects() {
 
     /**
      * This method returns a ProjectResolver that gives back the specified project-id when its getProjectId method is called.
-     * It also assumes it is the only project in the cluster state and throws if that is not the case.
+     * The ProjectResolver can work with cluster state containing multiple projects and its supportsMultipleProjects returns true.
      */
     public static ProjectResolver singleProject(ProjectId projectId) {
         return singleProject(projectId, false);
     }
 
+    /**
+     * This method returns a ProjectResolver that returns a random unique project-id.
+     * It also assumes it is the only project in the cluster state and throws if that is not the case.
+     * In addition, the ProjectResolvers returns false for supportsMultipleProjects.
+     */
+    public static ProjectResolver singleProjectOnly() {
+        return singleProjectOnly(ESTestCase.randomUniqueProjectId());
+    }
+
+    public static ProjectResolver singleProjectOnly(ProjectId projectId) {
+        return singleProject(projectId, true);
+    }
+
     private static ProjectResolver singleProject(ProjectId projectId, boolean only) {
         Objects.requireNonNull(projectId);
         return new ProjectResolver() {

test/framework/src/test/java/org/elasticsearch/cluster/project/TestProjectResolversTests.java

@@ -17,9 +17,11 @@
 import org.elasticsearch.test.ESTestCase;
 
 import static org.hamcrest.Matchers.contains;
+import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.greaterThan;
 import static org.hamcrest.Matchers.hasSize;
+import static org.hamcrest.Matchers.is;
 import static org.hamcrest.Matchers.notNullValue;
 
 public class TestProjectResolversTests extends ESTestCase {
@@ -37,17 +39,42 @@ public void testAllProjects() {
     public void testSingleProject() {
         final ProjectId projectId = randomUniqueProjectId();
         final ProjectResolver projectResolver = TestProjectResolvers.singleProject(projectId);
+        assertThat(projectResolver.supportsMultipleProjects(), is(true));
         assertThat(projectResolver.getProjectId(), equalTo(projectId));
 
         ClusterState state = buildClusterState(projectId, randomIntBetween(0, 10));
         assertThat(projectResolver.getProjectMetadata(state), notNullValue());
     }
 
-    public void testSingleProjectOnly_getProjectIdAndMetadata() {
+    public void testSingleProjectOnly() {
+        final ProjectResolver projectResolver = TestProjectResolvers.singleProjectOnly();
+        assertThat(projectResolver.supportsMultipleProjects(), is(false));
+        final var projectId = projectResolver.getProjectId();
+
+        ClusterState state = buildClusterState(projectId, 0);
+        assertThat(projectResolver.getProjectMetadata(state), notNullValue());
+
+        final IllegalStateException e = expectThrows(
+            IllegalStateException.class,
+            () -> projectResolver.getProjectMetadata(buildClusterState(projectId, randomIntBetween(1, 10)))
+        );
+        assertThat(e.getMessage(), containsString("Cluster has multiple projects"));
+    }
+
+    public void testDefaultProjectOnly() {
+        final ProjectResolver projectResolver = TestProjectResolvers.DEFAULT_PROJECT_ONLY;
+        assertThat(projectResolver.supportsMultipleProjects(), is(false));
+        assertThat(projectResolver.getProjectId(), equalTo(ProjectId.DEFAULT));
+
+        ClusterState state = buildClusterState(ProjectId.DEFAULT, 0);
+        assertThat(projectResolver.getProjectMetadata(state), notNullValue());
+    }
+
+    public void testMustExecuteFirst_getProjectIdAndMetadata() {
         final ProjectId projectId = randomUniqueProjectId();
         final ClusterState state = buildClusterState(projectId);
 
-        final ProjectResolver projectResolver = TestProjectResolvers.singleProjectOnly();
+        final ProjectResolver projectResolver = TestProjectResolvers.mustExecuteFirst();
         expectThrows(UnsupportedOperationException.class, projectResolver::getProjectId);
         expectThrows(UnsupportedOperationException.class, () -> projectResolver.getProjectMetadata(state));
 
@@ -57,9 +84,9 @@ public void testSingleProjectOnly_getProjectIdAndMetadata() {
         });
     }
 
-    public void testSingleProjectOnly_getProjectIds() {
+    public void testMustExecuteFirst_getProjectIds() {
         {
-            final ProjectResolver projectResolver = TestProjectResolvers.singleProjectOnly();
+            final ProjectResolver projectResolver = TestProjectResolvers.mustExecuteFirst();
             final ProjectId projectId = randomUniqueProjectId();
             ClusterState state = buildClusterState(projectId);
             assertThat(state.metadata().projects().values(), hasSize(1));
@@ -71,7 +98,7 @@ public void testSingleProjectOnly_getProjectIds() {
             });
         }
         {
-            final ProjectResolver projectResolver = TestProjectResolvers.singleProjectOnly();
+            final ProjectResolver projectResolver = TestProjectResolvers.mustExecuteFirst();
             final ProjectId projectId = randomUniqueProjectId();
             ClusterState state = buildClusterState(projectId, randomIntBetween(1, 10));
             assertThat(state.metadata().projects().values().size(), greaterThan(1));