coverage of switch case

[Manlio Perillo]

Hi.

There is a small issue with the go cover tool, when using multiple expressions in a case expression.

As an example, when testing the following function:

func foo(x int) {

    switch x {

    case 1, 2, 3, 5, 7:

        ...

    case 2:

        ... 

    }

}

A call to foo(1) will cause the entire line of the `case 1, 2, 3, 5, 7`expression to be highlighted, in the HTML page generated by go cover.

This is bad, since I can not tell if all the cases are covered.

This is not an issue with switch case, but an issue when multiple statements are on the same line.

Is this a limitation of the UI or a limitation of the coverage algorithm?

In general multi line statements are allowed by the grammar, but reformatted by go fmt, as an example:

func foo() {

if true { fmt.Println("true") } else { fmt.Println("false") }

}

So, if this is only an issue with the UI, I hope that a special case can be made to handle the switch statement.

Thanks  Manlio

[Ian Lance Taylor]

On Tue, Nov 24, 2015 at 6:45 AM, Manlio Perillo
<manlio....@gmail.com> wrote:
>
> There is a small issue with the go cover tool, when using multiple
> expressions in a case expression.
> As an example, when testing the following function:
>
> func foo(x int) {
> switch x {
> case 1, 2, 3, 5, 7:
> ...
> case 2:
> ...
> }
> }
>
> A call to foo(1) will cause the entire line of the `case 1, 2, 3, 5,
> 7`expression to be highlighted, in the HTML page generated by go cover.
> This is bad, since I can not tell if all the cases are covered.
> This is not an issue with switch case, but an issue when multiple statements
> are on the same line.
> Is this a limitation of the UI or a limitation of the coverage algorithm?

My understanding is that it is a limitation of the coverage tool,
which simply rewrites the program line by line.

Ian

[Rob Pike]

Working as designed. The cover tool works at block level, not expression level, so it cannot tell which of the case expressions was matched. See go tool cover -help.

-rob

On Tue, Nov 24, 2015 at 6:45 AM, Manlio Perillo <manlio....@gmail.com> wrote:

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[Rob Pike]

Not line by line but block by block, but yes, this is a limitation.

-rob