sanity: test FAILED_PRECONDITION on NodePublishVolume

According to the CSI spec, a `NodePublishVolume` RPC must return a
`FAILED_PRECONDITION` error when invoked with no `staging_target_path`
set, if `STAGE_UNSTAGE_VOLUME` is supported by the driver.

This patch adds a test to assert this.

See: https://github.com/container-storage-interface/spec/blob/87a27a2496565857ed564284eaa762587feb9453/spec.md#nodepublishvolume-errors

Author: NicolasT

hack/_apitest2/api_test.go

@@ -15,10 +15,10 @@ func TestMyDriverWithCustomTargetPaths(t *testing.T) {
 	var createTargetDirCalls, createStagingDirCalls,
 		removeTargetDirCalls, removeStagingDirCalls int
 
-	wantCreateTargetCalls := 4
-	wantCreateStagingCalls := 4
-	wantRemoveTargetCalls := 4
-	wantRemoveStagingCalls := 4
+	wantCreateTargetCalls := 5
+	wantCreateStagingCalls := 5
+	wantRemoveTargetCalls := 5
+	wantRemoveStagingCalls := 5
 
 	// tmpPath could be a CO specific directory under which all the target dirs
 	// are created. For k8s, it could be /var/lib/kubelet/pods under which the

mock/service/node.go

@@ -140,6 +140,10 @@ func (s *service) NodePublishVolume(
 		return nil, status.Error(codes.InvalidArgument, "Volume ID cannot be empty")
 	}
 
+	if len(req.GetStagingTargetPath()) == 0 {
+		return nil, status.Error(codes.FailedPrecondition, "StagingTarget Path cannot be empty")
+	}
+
 	if len(req.GetTargetPath()) == 0 {
 		return nil, status.Error(codes.InvalidArgument, "Target Path cannot be empty")
 	}

pkg/sanity/node.go

@@ -392,6 +392,21 @@ var _ = DescribeSanity("Node Service", func(sc *TestContext) {
 			Expect(serverError.Code()).To(Equal(codes.InvalidArgument))
 		})
 
+		It("should fail when no staging target path is provided", func() {
+			if !nodeStageSupported {
+				Skip("STAGE_UNSTAGE_VOLUME not supported")
+			}
+
+			req.StagingTargetPath = ""
+
+			_, err := c.NodePublishVolume(context.Background(), req)
+			Expect(err).To(HaveOccurred())
+
+			serverError, ok := status.FromError(err)
+			Expect(ok).To(BeTrue())
+			Expect(serverError.Code()).To(Equal(codes.FailedPrecondition))
+		})
+
 		It("should fail when no volume capability is provided", func() {
 			req.VolumeCapability = nil