Context#JSON() adds a new line character to the end of the JSON response

[yu-yk]

Hi,

I am writing some uint test and I found that the c.JSON function will add a \n to the end of JSON response and leads my test fails.
In the documentation, the testing data doesn't contains the \n, however in the json_test.go it does.

>>>>>>>doc (https://echo.labstack.com/guide/testing/)

assert.Equal(t, userJSON, rec.Body.String())

==================================

assert.Equal(userJSON+"\n", rec.Body.String())

<<<<<<<<<json_test.go (https://github.com/labstack/echo/blob/master/json_test.go)

And when I search this issue on the internet, gin framework also has this issue before and they treated it is as a bug and fixed it.
How about echo? Is there any reason keeping this strange behaviour?

here is a simple demo to reproduce the issue:
https://github.com/yu-yk/echo-newline

[aldas]

Echo uses standard library to encode JSON.

echo/json.go

Lines 15 to 19 in 5e791b0

	enc := json.NewEncoder(c.Response())
	if indent != "" {
	enc.SetIndent("", indent)
	}
	return enc.Encode(i)

This is similar question with answer where and when and why this newline is added https://stackoverflow.com/a/36320146

[yu-yk]

I see, so there is no plan or reason to change to use the json.Marshal inside the Serialize() and we need to add the newline when doing some response matching stuff?
If so then I would like to make a minor PR to add back that missing \n in the documentation page.