refactor: cli: address comments from #4240 (#4259)

cli/cliui/table.go

@@ -67,7 +67,7 @@ func DisplayTable(out any, sort string, filterColumns []string) (string, error)
 	}
 
 	// Get the list of table column headers.
-	headersRaw, err := TypeToTableHeaders(v.Type().Elem())
+	headersRaw, err := typeToTableHeaders(v.Type().Elem())
 	if err != nil {
 		return "", xerrors.Errorf("get table headers recursively for type %q: %w", v.Type().Elem().String(), err)
 	}
@@ -207,10 +207,10 @@ func isStructOrStructPointer(t reflect.Type) bool {
 	return t.Kind() == reflect.Struct || (t.Kind() == reflect.Pointer && t.Elem().Kind() == reflect.Struct)
 }
 
-// TypeToTableHeaders converts a type to a slice of column names. If the given
+// typeToTableHeaders converts a type to a slice of column names. If the given
 // type is invalid (not a struct or a pointer to a struct, has invalid table
 // tags, etc.), an error is returned.
-func TypeToTableHeaders(t reflect.Type) ([]string, error) {
+func typeToTableHeaders(t reflect.Type) ([]string, error) {
 	if !isStructOrStructPointer(t) {
 		return nil, xerrors.Errorf("typeToTableHeaders called with a non-struct or a non-pointer-to-a-struct type")
 	}
@@ -235,7 +235,7 @@ func TypeToTableHeaders(t reflect.Type) ([]string, error) {
 				return nil, xerrors.Errorf("field %q in type %q is marked as recursive but does not contain a struct or a pointer to a struct", field.Name, t.String())
 			}
 
-			childNames, err := TypeToTableHeaders(fieldType)
+			childNames, err := typeToTableHeaders(fieldType)
 			if err != nil {
 				return nil, xerrors.Errorf("get child field header names for field %q in type %q: %w", field.Name, fieldType.String(), err)
 			}
@@ -305,3 +305,18 @@ func valueToTableMap(val reflect.Value) (map[string]any, error) {
 
 	return row, nil
 }
+
+// TableHeaders returns the table header names of all
+// fields in tSlice. tSlice must be a slice of some type.
+func TableHeaders(tSlice any) ([]string, error) {
+	v := reflect.Indirect(reflect.ValueOf(tSlice))
+	rawHeaders, err := typeToTableHeaders(v.Type().Elem())
+	if err != nil {
+		return nil, xerrors.Errorf("type to table headers: %w", err)
+	}
+	out := make([]string, 0, len(rawHeaders))
+	for _, hdr := range rawHeaders {
+		out = append(out, strings.Replace(hdr, " ", "_", -1))
+	}
+	return out, nil
+}

cli/cliui/table_test.go

@@ -327,6 +327,28 @@ baz   baz1        baz3              Aug  2 15:49:10
 	})
 }
 
+func Test_TableHeaders(t *testing.T) {
+	t.Parallel()
+	s := []tableTest1{}
+	expectedFields := []string{
+		"name",
+		"age",
+		"roles",
+		"sub_1_name",
+		"sub_1_age",
+		"sub_2_name",
+		"sub_2_age",
+		"sub_3_inner_name",
+		"sub_3_inner_age",
+		"sub_4",
+		"time",
+		"time_ptr",
+	}
+	headers, err := cliui.TableHeaders(s)
+	require.NoError(t, err)
+	require.EqualValues(t, expectedFields, headers)
+}
+
 // compareTables normalizes the incoming table lines
 func compareTables(t *testing.T, expected, out string) {
 	t.Helper()

cli/list.go

@@ -2,7 +2,6 @@ package cli
 
 import (
 	"fmt"
-	"reflect"
 	"strings"
 	"time"
 
@@ -128,14 +127,10 @@ func list() *cobra.Command {
 		},
 	}
 
-	v := reflect.Indirect(reflect.ValueOf(displayWorkspaces))
-	availColumns, err := cliui.TypeToTableHeaders(v.Type().Elem())
+	availColumns, err := cliui.TableHeaders(displayWorkspaces)
 	if err != nil {
 		panic(err)
 	}
-	for i, s := range availColumns {
-		availColumns[i] = strings.Replace(s, " ", "_", -1)
-	}
 	columnString := strings.Join(availColumns[:], ", ")
 
 	cmd.Flags().BoolVarP(&all, "all", "a", false,