feat: add tmpl function `required` (#1188)

Co-authored-by: Raymond Liu (RD-TW) <raymond_liu@trend.com.tw>

pkg/tmpl/context_funcs.go

@@ -26,6 +26,7 @@ func (c *Context) createFuncMap() template.FuncMap {
 		"get":            get,
 		"getOrNil":       getOrNil,
 		"tpl":            c.Tpl,
+		"required":       Required,
 	}
 	if c.preRender {
 		// disable potential side-effect template calls
@@ -242,3 +243,15 @@ func RequiredEnv(name string) (string, error) {
 
 	return "", fmt.Errorf("required env var `%s` is not set", name)
 }
+
+func Required(warn string, val interface{}) (interface{}, error) {
+	if val == nil {
+		return nil, fmt.Errorf(warn)
+	} else if _, ok := val.(string); ok {
+		if val == "" {
+			return nil, fmt.Errorf(warn)
+		}
+	}
+
+	return val, nil
+}

pkg/tmpl/context_funcs_test.go

@@ -133,3 +133,47 @@ func TestTpl(t *testing.T) {
 		t.Errorf("unexpected result: expected=%v, actual=%v", expected, actual)
 	}
 }
+
+func TestRequired(t *testing.T) {
+	type args struct {
+		warn string
+		val  interface{}
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    interface{}
+		wantErr bool
+	}{
+		{
+			name:    "required val is nil",
+			args:    args{warn: "This value is required", val: nil},
+			want:    nil,
+			wantErr: true,
+		},
+		{
+			name:    "required val is empty string",
+			args:    args{warn: "This value is required", val: ""},
+			want:    nil,
+			wantErr: true,
+		},
+		{
+			name:    "required val is existed",
+			args:    args{warn: "This value is required", val: "foo"},
+			want:    "foo",
+			wantErr: false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := Required(tt.args.warn, tt.args.val)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("Required() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("Required() got = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

pkg/tmpl/context_tmpl_test.go

@@ -250,3 +250,81 @@ func Test_renderTemplateToString(t *testing.T) {
 		})
 	}
 }
+
+func TestRenderTemplate_Required(t *testing.T) {
+	tests := []struct {
+		name    string
+		s       string
+		data    map[string]interface{}
+		want    string
+		wantErr bool
+	}{
+		{
+			name: ".foo is existed",
+			s:    `{{ required ".foo.bar is required" .foo }}`,
+			data: map[string]interface{}{
+				"foo": "bar",
+			},
+			want:    "bar",
+			wantErr: false,
+		},
+		{
+			name: ".foo.bar is existed",
+			s:    `{{ required "foo.bar is required" .foo.bar }}`,
+			data: map[string]interface{}{
+				"foo": map[string]interface{}{
+					"bar": "FOO_BAR",
+				},
+			},
+			want:    "FOO_BAR",
+			wantErr: false,
+		},
+		{
+			name: ".foo.bar is existed but value is nil",
+			s:    `{{ required "foo.bar is required" .foo.bar }}`,
+			data: map[string]interface{}{
+				"foo": map[string]interface{}{
+					"bar": nil,
+				},
+			},
+			wantErr: true,
+		},
+		{
+			name: ".foo.bar is existed but value is empty string",
+			s:    `{{ required "foo.bar is required" .foo.bar }}`,
+			data: map[string]interface{}{
+				"foo": map[string]interface{}{
+					"bar": "",
+				},
+			},
+			wantErr: true,
+		},
+		{
+			name: ".foo is nil",
+			s:    `{{ required "foo is required" .foo }}`,
+			data: map[string]interface{}{
+				"foo": nil,
+			},
+			wantErr: true,
+		},
+		{
+			name: ".foo is a empty string",
+			s:    `{{ required "foo is required" .foo }}`,
+			data: map[string]interface{}{
+				"foo": "",
+			},
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		got, err := renderTemplateToString(tt.s, tt.data)
+		if (err != nil) != tt.wantErr {
+			t.Errorf("renderTemplateToString() for %s error = %v, wantErr %v", tt.name, err, tt.wantErr)
+			return
+		}
+		if got != tt.want {
+			t.Errorf("renderTemplateToString() for %s = %v, want %v", tt.name, got, tt.want)
+		}
+	}
+}