add FieldName test case

Signed-off-by: sivchari <shibuuuu5@gmail.com>

Author: sivchari

pkg/analysis/utils/utils_test.go

@@ -0,0 +1,67 @@
+package utils_test
+
+import (
+	"go/ast"
+	"testing"
+
+	"sigs.k8s.io/kube-api-linter/pkg/analysis/utils"
+)
+
+func TestFieldName(t *testing.T) {
+	t.Parallel()
+
+	cases := map[string]struct {
+		field *ast.Field
+		want  string
+	}{
+		"field has Names": {
+			field: &ast.Field{
+				Names: []*ast.Ident{
+					{
+						Name: "foo",
+					},
+				},
+			},
+			want: "foo",
+		},
+		"filed has no Names, but is an Ident": {
+			field: &ast.Field{
+				Type: &ast.Ident{
+					Name: "foo",
+				},
+			},
+			want: "foo",
+		},
+		"field has no Names, but is a StarExpr with an Ident": {
+			field: &ast.Field{
+				Type: &ast.StarExpr{
+					X: &ast.Ident{
+						Name: "foo",
+					},
+				},
+			},
+			want: "foo",
+		},
+		"field has no Names, and is not an Ident or StarExpr": {
+			field: &ast.Field{
+				Type: &ast.ArrayType{
+					Elt: &ast.Ident{
+						Name: "foo",
+					},
+				},
+			},
+			want: "",
+		},
+	}
+
+	for name, tc := range cases {
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			got := utils.FieldName(tc.field)
+			if got != tc.want {
+				t.Errorf("got %q, want %q", got, tc.want)
+			}
+		})
+	}
+}