usability: Handle Exceptions for no resources

pkg/blockdevice/blockdevice.go

@@ -87,6 +87,9 @@ 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{}{"", "", "", "", "", "", ""}})
 	}
+	if len(rows) == 0 {
+		return util.HandleEmptyTableError("Block Device", k.Ns, "")
+	}
 	// Show the output using cli-runtime
 	util.TablePrinter(util.BDTreeListColumnDefinations, rows, printers.PrintOptions{Wide: true})
 	return nil

pkg/storage/lvmlocalpv.go

@@ -55,8 +55,7 @@ func GetVolumeGroups(c *client.K8sClient, vgs []string) ([]metav1.TableColumnDef
 	}
 	// 3. Actually print the table or return an error
 	if len(rows) == 0 {
-		// TODO: Improve this in issue #56
-		return nil, nil, fmt.Errorf("no lvm volumegroups found")
+		return nil, nil, util.HandleEmptyTableError("lvm Volumegroups", c.Ns, "")
 	}
 	return util.LVMvolgroupListColumnDefinitions, rows, nil
 }

pkg/storage/storage.go

@@ -36,20 +36,31 @@ func Get(pools []string, openebsNS string, casType string) error {
 		if err != nil {
 			return err
 		}
+		if len(rows) == 0 {
+			return util.HandleEmptyTableError("Storage", openebsNS, casType)
+		}
 		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/storage/zfslocalpv.go

@@ -57,7 +57,7 @@ func GetZFSPools(c *client.K8sClient, zfsnodes []string) ([]metav1.TableColumnDe
 	}
 	// 3. Actually print the table or return an error
 	if len(rows) == 0 {
-		return nil, nil, fmt.Errorf("no zfspools found")
+		return nil, nil, util.HandleEmptyTableError("zfs pools", c.Ns, "")
 	}
 	return util.ZFSPoolListColumnDefinitions, rows, nil
 }

pkg/util/error.go

@@ -40,3 +40,16 @@ func CheckErr(err error, handleErr func(string)) {
 	}
 	handleErr(err.Error())
 }
+
+// Handle Empty handles error when resources or set of resources are not found
+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 != "" && !IsValidCasType(casType) {
+		return fmt.Errorf("cas-type %s not supported", casType)
+	} else {
+		return fmt.Errorf("no %s found in %s namespace", resource, ns)
+	}
+}

pkg/util/error_test.go

@@ -57,3 +57,69 @@ 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
+		expected error
+	}{
+		{
+			"No Namespace and cas",
+			args{
+				resource: "ResourceType",
+				ns:       "",
+				casType:  "",
+			},
+			fmt.Errorf("no ResourceType found in your cluster"),
+		},
+		{
+			"Wrong cas or Namespace",
+			args{
+				resource: "ResourceType",
+				ns:       "InValid",
+				casType:  "jiva",
+			},
+			fmt.Errorf("no jiva ResourceType found in InValid namespace"),
+		},
+		{
+			"",
+			args{
+				resource: "ResourceType",
+				ns:       "invalid",
+				casType:  "",
+			},
+			fmt.Errorf("no ResourceType found in invalid namespace"),
+		},
+		{
+			"Wrong cas type in all namespace",
+			args{
+				resource: "ResourceType",
+				ns:       "",
+				casType:  "invalid",
+			},
+			fmt.Errorf("cas-type invalid not supported"),
+		},
+		{
+			"Wrong Namespace and all cas types",
+			args{
+				resource: "ResourceType",
+				ns:       "InValid",
+				casType:  "",
+			},
+			fmt.Errorf("no ResourceType found in InValid namespace"),
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if tResult := HandleEmptyTableError(tt.args.resource, tt.args.ns, tt.args.casType); tResult.Error() != tt.expected.Error() {
+				t.Errorf("HandleEmptyTableError(): expected: %s, got: %s", tt.expected, tResult)
+			}
+		})
+	}
+}

pkg/volume/volume.go

@@ -62,7 +62,11 @@ func Get(vols []string, openebsNS, casType string) error {
 			}
 		}
 	}
-	// 3. Print the volumes from rows
+
+	// 3. Return Error or Print volumes from rows
+	if len(rows) == 0 {
+		return util.HandleEmptyTableError("Volume", openebsNS, casType)
+	}
 	util.TablePrinter(util.VolumeListColumnDefinations, rows, printers.PrintOptions{Wide: true})
 	return nil
 }