introducing no field is empty assertion

Author: PeterEFinch

assert/assertion_format.go

@@ -2148,3 +2148,38 @@ func buildErrorChainString(err error) string {
 	}
 	return chain
 }
+
+// NoFieldIsEmpty asserts that object, which must be a struct or eventually reference to one, has no empty exported fields.
+func NoFieldIsEmpty(t TestingT, object interface{}, msgAndArgs ...interface{}) bool {
+	if reflect.TypeOf(object).Kind() == reflect.Ptr {
+		return NoFieldIsEmpty(t, reflect.ValueOf(object).Elem().Interface(), msgAndArgs)
+	}
+
+	if h, ok := t.(tHelper); ok {
+		h.Helper()
+	}
+
+	objectType := reflect.TypeOf(object)
+	if objectType.Kind() != reflect.Struct {
+		return Fail(t, "Input must be a struct or eventually reference one", msgAndArgs...)
+	}
+
+	var emptyFields []string
+	objectValue := reflect.ValueOf(object)
+	for i := 0; i < objectType.NumField(); i++ {
+		field := objectType.Field(i)
+		if !field.IsExported() {
+			continue
+		}
+
+		if isEmpty(objectValue.Field(i).Interface()) {
+			emptyFields = append(emptyFields, field.Name)
+		}
+	}
+
+	if len(emptyFields) > 0 {
+		return Fail(t, fmt.Sprintf("Object contained empty fields: %s", strings.Join(emptyFields, ", ")), msgAndArgs...)
+	}
+
+	return true
+}

assert/assertion_forward.go

@@ -3279,3 +3279,88 @@ func TestErrorAs(t *testing.T) {
 		})
 	}
 }
+
+func TestNoFieldIsEmpty(t *testing.T) {
+	str := "a string"
+	tests := []struct {
+		name         string
+		input        interface{}
+		result       bool
+		resultErrMsg string
+	}{
+		{
+			name: "success",
+			input: struct {
+				Float64   float64
+				Func      func()
+				Int       int
+				Interface interface{}
+				Pointer   *string
+				Slice     []string
+				String    string
+				Struct    struct{ String string }
+			}{
+				Float64:   1.5,
+				Func:      func() {},
+				Int:       1,
+				Interface: "interface",
+				Pointer:   &str,
+				Slice:     []string{"a", "b"},
+				String:    "a string",
+				Struct:    struct{ String string }{String: "a nested string"},
+			},
+			result: true,
+		},
+		{
+			name: "success_pointer",
+			input: &struct {
+				String string
+			}{
+				String: "a string",
+			},
+			result: true,
+		},
+		{
+			name:   "success_unexported",
+			input:  struct{ unexported string }{},
+			result: true,
+		},
+		{
+			name: "failure",
+			input: struct {
+				Float64   float64
+				Func      func()
+				Int       int
+				Interface interface{}
+				Pointer   *string
+				Slice     []string
+				String    string
+				Struct    struct{ String string }
+			}{},
+			result:       false,
+			resultErrMsg: "Object contained empty fields: Float64, Func, Int, Interface, Pointer, Slice, String, Struct\n",
+		},
+		{
+			name: "failure_partial",
+			input: struct {
+				StringA string
+				StringB string
+			}{StringA: "not_empty"},
+			result:       false,
+			resultErrMsg: "Object contained empty fields: StringB\n",
+		},
+		{
+			name:         "failure_wrong_type",
+			input:        "a string is not a struct",
+			result:       false,
+			resultErrMsg: "Input must be a struct or eventually reference one\n",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			mockT := new(captureTestingT)
+			result := NoFieldIsEmpty(mockT, tt.input)
+			mockT.checkResultAndErrMsg(t, tt.result, result, tt.resultErrMsg)
+		})
+	}
+}