usability: Handle Exceptions for no resource lists

Signed-off-by: Abhishek-kumar09 <abhimait1909@gmail.com>

pkg/blockdevice/blockdevice.go

@@ -87,7 +87,11 @@ func createTreeByNode(k *client.K8sClient, bdNames []string) error {
 		// Add an empty row so that the tree looks neat
 		rows = append(rows, metav1.TableRow{Cells: []interface{}{"", "", "", "", "", "", ""}})
 	}
-	// Show the output using cli-runtime
-	util.TablePrinter(util.BDTreeListColumnDefinations, rows, printers.PrintOptions{Wide: true})
+	if len(rows) == 0 {
+		util.HandleEmptyTableError("Block Device", k.Ns, "")
+	} else {
+		// Show the output using cli-runtime
+		util.TablePrinter(util.BDTreeListColumnDefinations, rows, printers.PrintOptions{Wide: true})
+	}
 	return nil
 }

pkg/storage/storage.go

@@ -36,20 +36,32 @@ func Get(pools []string, openebsNS string, casType string) error {
 		if err != nil {
 			return err
 		}
-		util.TablePrinter(header, rows, printers.PrintOptions{Wide: true})
+		if len(rows) == 0 {
+			return util.HandleEmptyTableError("Storage", openebsNS, casType)
+		} else {
+			util.TablePrinter(header, rows, printers.PrintOptions{Wide: true})
+		}
 	} else if casType != "" {
 		return fmt.Errorf("cas-type %s is not supported", casType)
 	} else {
+		storageResourcesFound := false
 		// 3. Call all functions & exit
 		for _, f := range CasList() {
 			header, row, err := f(k, pools)
 			if err == nil {
+				if len(row) > 0 {
+					storageResourcesFound = true
+				}
 				// 4. Find the correct heading & print the rows
 				util.TablePrinter(header, row, printers.PrintOptions{Wide: true})
 				// A visual separator for different cas-type pools/storage entities
 				fmt.Println()
 			}
 		}
+
+		if !storageResourcesFound {
+			return util.HandleEmptyTableError("Storage", openebsNS, casType)
+		}
 	}
 	return nil
 }

pkg/util/error.go

@@ -40,3 +40,16 @@ func CheckErr(err error, handleErr func(string)) {
 	}
 	handleErr(err.Error())
 }
+
+// Handle Empty Table Error
+func HandleEmptyTableError(resource string, ns string, casType string) error {
+	if ns == "" && casType == "" {
+		return fmt.Errorf("no %s found in your cluster", resource)
+	} else if ns != "" && casType != "" {
+		return fmt.Errorf("no %s %s found in %s namespace", casType, resource, ns)
+	} else if casType != "" {
+		return fmt.Errorf("unknown cas-type %s", casType)
+	} else {
+		return fmt.Errorf("no %s found in %s namespace", resource, ns)
+	}
+}

pkg/util/error_test.go

@@ -57,3 +57,53 @@ func TestCheckErr(t *testing.T) {
 		})
 	}
 }
+
+func TestHandleEmptyTableError(t *testing.T) {
+	type args struct {
+		resource string
+		ns       string
+		casType  string
+	}
+	tests := []struct {
+		name string
+		args args
+	}{
+		{
+			"No Namespace and cas",
+			args{
+				resource: "ResourceType",
+				ns:       "",
+				casType:  "",
+			},
+		},
+		{
+			"Wrong cas or Namespace",
+			args{
+				resource: "ResourceType",
+				ns:       "InValidNamespace",
+				casType:  "jiva",
+			},
+		},
+		{
+			"Wrong cas type in all namespace",
+			args{
+				resource: "ResourceType",
+				ns:       "",
+				casType:  "invalid",
+			},
+		},
+		{
+			"Wrong Namespace and all cas types",
+			args{
+				resource: "ResourceType",
+				ns:       "InValidNamespace",
+				casType:  "",
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			HandleEmptyTableError(tt.args.resource, tt.args.ns, tt.args.casType)
+		})
+	}
+}

pkg/volume/volume.go

@@ -62,8 +62,13 @@ func Get(vols []string, openebsNS, casType string) error {
 			}
 		}
 	}
-	// 3. Print the volumes from rows
-	util.TablePrinter(util.VolumeListColumnDefinations, rows, printers.PrintOptions{Wide: true})
+
+	if len(rows) == 0 {
+		return util.HandleEmptyTableError("Volume", openebsNS, casType)
+	} else {
+		// 3. Print the volumes from rows
+		util.TablePrinter(util.VolumeListColumnDefinations, rows, printers.PrintOptions{Wide: true})
+	}
 	return nil
 }