Fill in namespace capabilities in describe response (#2228)

Fill in namespace capabilities in describe response

Author: Quinn-With-Two-Ns

temporal-test-server/src/main/java/io/temporal/internal/testservice/TestWorkflowService.java

@@ -1362,6 +1362,11 @@ public void describeNamespace(
                       .setName(request.getNamespace())
                       .setState(NamespaceState.NAMESPACE_STATE_REGISTERED)
                       .setId(namespaceId)
+                      .setCapabilities(
+                          NamespaceInfo.Capabilities.newBuilder()
+                              .setEagerWorkflowStart(true)
+                              .setAsyncUpdate(true)
+                              .setSyncUpdate(true))
                       .build())
               .build();
       responseObserver.onNext(result);

temporal-test-server/src/test/java/io/temporal/testserver/functional/DescribeNamespaceTest.java

@@ -21,6 +21,7 @@
 package io.temporal.testserver.functional;
 
 import static org.junit.Assert.*;
+import static org.junit.Assume.assumeFalse;
 
 import io.grpc.Status;
 import io.grpc.StatusRuntimeException;
@@ -53,6 +54,27 @@ public void testDescribeNamespace() {
     assertTrue(describeNamespaceResponse.getNamespaceInfo().getId().length() > 0);
   }
 
+  @Test
+  public void testDescribeNamespaceCapabilities() {
+    assumeFalse(
+        "Real Server doesn't support namespace capabilities yet",
+        SDKTestWorkflowRule.useExternalService);
+
+    DescribeNamespaceResponse describeNamespaceResponse =
+        testWorkflowRule
+            .getWorkflowServiceStubs()
+            .blockingStub()
+            .describeNamespace(
+                DescribeNamespaceRequest.newBuilder()
+                    .setNamespace(RegisterTestNamespace.NAMESPACE)
+                    .build());
+
+    assertTrue(
+        describeNamespaceResponse.getNamespaceInfo().getCapabilities().getEagerWorkflowStart());
+    assertTrue(describeNamespaceResponse.getNamespaceInfo().getCapabilities().getSyncUpdate());
+    assertTrue(describeNamespaceResponse.getNamespaceInfo().getCapabilities().getAsyncUpdate());
+  }
+
   @Test
   public void noNamespaceSet() {
     StatusRuntimeException ex =