just add some unit tests (#16291)

* code.gitea.io/gitea/routers/utils coverage: 100.0%

* code.gitea.io/gitea/routers/install 0% -> 5.0%

* ConvertUtf8ToUtf8mb4: make sure DBType is mysql

routers/utils/utils_test.go

@@ -62,7 +62,41 @@ func TestIsExternalURL(t *testing.T) {
 			"//try.gitea.io/test?param=false"),
 		newTest(false,
 			"/hey/hey/hey#3244"),
+		newTest(true,
+			"://missing protocol scheme"),
 	} {
 		assert.Equal(t, test.Expected, IsExternalURL(test.RawURL))
 	}
 }
+
+func TestSanitizeFlashErrorString(t *testing.T) {
+	tests := []struct {
+		name string
+		arg  string
+		want string
+	}{
+		{
+			name: "no error",
+			arg:  "",
+			want: "",
+		},
+		{
+			name: "normal error",
+			arg:  "can not open file: \"abc.exe\"",
+			want: "can not open file: "abc.exe"",
+		},
+		{
+			name: "line break error",
+			arg:  "some error:\n\nawesome!",
+			want: "some error:<br><br>awesome!",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := SanitizeFlashErrorString(tt.arg); got != tt.want {
+				t.Errorf("SanitizeFlashErrorString() = '%v', want '%v'", got, tt.want)
+			}
+		})
+	}
+}