[bugfix] use start + end line in regex when validating emoji via API (#2671)

internal/validate/formvalidation.go

@@ -191,7 +191,7 @@ func CustomCSS(customCSS string) error {
 // for emoji shortcodes, to figure out whether it's a valid shortcode, ie., 2-30 characters,
 // a-zA-Z, numbers, and underscores.
 func EmojiShortcode(shortcode string) error {
-	if !regexes.EmojiShortcode.MatchString(shortcode) {
+	if !regexes.EmojiValidator.MatchString(shortcode) {
 		return fmt.Errorf("shortcode %s did not pass validation, must be between 2 and 30 characters, letters, numbers, and underscores only", shortcode)
 	}
 	return nil

internal/validate/formvalidation_test.go

@@ -321,6 +321,63 @@ func (suite *ValidationTestSuite) TestValidateCustomCSSTooLongUnicode() {
 	suite.EqualError(err, "custom_css must be less than 5 characters, but submitted custom_css was 10 characters")
 }
 
+func (suite *ValidationTestSuite) TestValidateEmojiShortcode() {
+	type testStruct struct {
+		shortcode string
+		ok        bool
+	}
+
+	for _, test := range []testStruct{
+		{
+			shortcode: "peepee",
+			ok:        true,
+		},
+		{
+			shortcode: "poo-poo",
+			ok:        false,
+		},
+		{
+			shortcode: "-peepee",
+			ok:        false,
+		},
+		{
+			shortcode: "p",
+			ok:        false,
+		},
+		{
+			shortcode: "pp",
+			ok:        true,
+		},
+		{
+			shortcode: "6969",
+			ok:        true,
+		},
+		{
+			shortcode: "__peepee",
+			ok:        true,
+		},
+		{
+			shortcode: "_",
+			ok:        false,
+		},
+		{
+			// Too long.
+			shortcode: "_XxX_Ultimate_Gamer_dude_6969_420_",
+			ok:        false,
+		},
+		{
+			shortcode: "_XxX_Ultimate_Gamer_dude_6969_",
+			ok:        true,
+		},
+	} {
+		err := validate.EmojiShortcode(test.shortcode)
+		ok := err == nil
+		if !suite.Equal(test.ok, ok) {
+			suite.T().Logf("fail on %s", test.shortcode)
+		}
+	}
+}
+
 func TestValidationTestSuite(t *testing.T) {
 	suite.Run(t, new(ValidationTestSuite))
 }