check test failure message for Empty and NotEmpty

Only the tests are updated, code is unchanged.

Previously, the tests were checking only the result of the asserter.
Using captureTestingT helper allows to check the error message

Author: ccoVeille

assert/assertions_test.go

@@ -1704,6 +1704,142 @@ func TestEmpty(t *testing.T) {
 	False(t, Empty(mockT, TString("abc")), "non-empty aliased string is empty")
 	False(t, Empty(mockT, xP), "ptr to non-nil value is not empty")
 	False(t, Empty(mockT, [1]int{42}), "array is not state")
+
+	// error messages validation
+	tests := []struct {
+		name           string
+		value          interface{}
+		expectedResult bool
+		expectedErrMsg string
+	}{
+		{
+			name:           "Non Empty string is not empty",
+			value:          "something",
+			expectedResult: false,
+			expectedErrMsg: "Should be empty, but was something\n",
+		},
+		{
+			name:           "Non nil object is not empty",
+			value:          errors.New("something"),
+			expectedResult: false,
+			expectedErrMsg: "Should be empty, but was something\n",
+		},
+		{
+			name:           "Non empty string array is not empty",
+			value:          []string{"something"},
+			expectedResult: false,
+			expectedErrMsg: "Should be empty, but was [something]\n",
+		},
+		{
+			name:           "Non-zero int value is not empty",
+			value:          1,
+			expectedResult: false,
+			expectedErrMsg: "Should be empty, but was 1\n",
+		},
+		{
+			name:           "True value is not empty",
+			value:          true,
+			expectedResult: false,
+			expectedErrMsg: "Should be empty, but was true\n",
+		},
+		{
+			name:           "Channel with values is not empty",
+			value:          chWithValue,
+			expectedResult: false,
+			expectedErrMsg: fmt.Sprintf("Should be empty, but was %v\n", chWithValue),
+		},
+		{
+			name:           "struct with initialized values is empty",
+			value:          TStruct{x: 1},
+			expectedResult: false,
+			expectedErrMsg: "Should be empty, but was {1}\n",
+		},
+		{
+			name:           "non-empty aliased string is empty",
+			value:          TString("abc"),
+			expectedResult: false,
+			expectedErrMsg: "Should be empty, but was abc\n",
+		},
+		{
+			name:           "ptr to non-nil value is not empty",
+			value:          xP,
+			expectedResult: false,
+			expectedErrMsg: fmt.Sprintf("Should be empty, but was %p\n", xP),
+		},
+		{
+			name:           "array is not state",
+			value:          [1]int{42},
+			expectedResult: false,
+			expectedErrMsg: "Should be empty, but was [42]\n",
+		},
+
+		// Here are some edge cases
+		{
+			name:           "string with only spaces is not empty",
+			value:          "   ",
+			expectedResult: false,
+			expectedErrMsg: "Should be empty, but was    \n", // TODO FIX THIS strange error message
+		},
+		{
+			name:           "string with a line feed is not empty",
+			value:          "\n",
+			expectedResult: false,
+			// TODO This is the exact same error message as for an empty string
+			expectedErrMsg: "Should be empty, but was \n", // TODO FIX THIS strange error message
+		},
+		{
+			name:           "string with only tabulation and lines feed is not empty",
+			value:          "\n\t\n",
+			expectedResult: false,
+			// TODO The line feeds and tab are not helping to spot what is expected
+			expectedErrMsg: "" + // this syntax is used to show how errors are reported.
+				"Should be empty, but was \n" +
+				"\t\n",
+		},
+		{
+			name:           "string with trailing lines feed is not empty",
+			value:          "foo\n\n",
+			expectedResult: false,
+			// TODO it's not clear if one or two lines feed are expected
+			expectedErrMsg: "Should be empty, but was foo\n\n",
+		},
+		{
+			name:           "string with leading and trailing tabulation and lines feed is not empty",
+			value:          "\n\nfoo\t\n\t\n",
+			expectedResult: false,
+			// TODO The line feeds and tab are not helping to figure what is expected
+			expectedErrMsg: "" +
+				"Should be empty, but was \n" +
+				"\n" +
+				"foo\t\n" +
+				"\t\n",
+		},
+
+		{
+			name:           "non-printable character is not empty",
+			value:          "\u00a0", // NO-BREAK SPACE UNICODE CHARACTER
+			expectedResult: false,
+			// TODO here you cannot figure out what is expected
+			expectedErrMsg: "Should be empty, but was \u00a0\n",
+		},
+
+		// Here we are testing there is no error message on success
+		{
+			name:           "Empty string is empty",
+			value:          "",
+			expectedResult: true,
+			expectedErrMsg: "",
+		},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			mockCT := new(captureTestingT)
+			res := Empty(mockCT, tt.value)
+			mockCT.checkResultAndErrMsg(t, res, tt.expectedResult, tt.expectedErrMsg)
+		})
+	}
 }
 
 func TestNotEmpty(t *testing.T) {
@@ -1726,6 +1862,68 @@ func TestNotEmpty(t *testing.T) {
 	True(t, NotEmpty(mockT, true), "True value is not empty")
 	True(t, NotEmpty(mockT, chWithValue), "Channel with values is not empty")
 	True(t, NotEmpty(mockT, [1]int{42}), "array is not state")
+
+	// error messages validation
+	tests := []struct {
+		name           string
+		value          interface{}
+		expectedResult bool
+		expectedErrMsg string
+	}{
+		{
+			name:           "Empty string is empty",
+			value:          "",
+			expectedResult: false,
+			expectedErrMsg: `Should NOT be empty, but was ` + "\n", // TODO FIX THIS strange error message
+		},
+		{
+			name:           "Nil is empty",
+			value:          nil,
+			expectedResult: false,
+			expectedErrMsg: "Should NOT be empty, but was <nil>\n",
+		},
+		{
+			name:           "Empty string array is empty",
+			value:          []string{},
+			expectedResult: false,
+			expectedErrMsg: "Should NOT be empty, but was []\n",
+		},
+		{
+			name:           "Zero int value is empty",
+			value:          0,
+			expectedResult: false,
+			expectedErrMsg: "Should NOT be empty, but was 0\n",
+		},
+		{
+			name:           "False value is empty",
+			value:          false,
+			expectedResult: false,
+			expectedErrMsg: "Should NOT be empty, but was false\n",
+		},
+		{
+			name:           "array is state",
+			value:          [1]int{},
+			expectedResult: false,
+			expectedErrMsg: "Should NOT be empty, but was [0]\n",
+		},
+
+		// Here we are testing there is no error message on success
+		{
+			name:           "Non Empty string is not empty",
+			value:          "something",
+			expectedResult: true,
+			expectedErrMsg: "",
+		},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			mockCT := new(captureTestingT)
+			res := NotEmpty(mockCT, tt.value)
+			mockCT.checkResultAndErrMsg(t, tt.expectedResult, res, tt.expectedErrMsg)
+		})
+	}
 }
 
 func Test_getLen(t *testing.T) {