That omission is not really relevant. Even if I included an assertion in
the test, it wouldn't affect the point I am making. I just wanted to have
at least some source code to reproduce the problem - adding if
Calculator(1,2) != 3 {t.Error(...)} would make it more of a complete test,
but my point is entirely different. My point is that top level functions
calling further functions leads to "inflated" coverage numbers, because I
am explicitly not testing any of the downstream functionality, just the top
level function.
Again, this is not really a technical issue.
On Wednesday, 18 March 2020 13:29:05 UTC+1, Robert Engels wrote:
>
> It’s because you are not writing the top level test correctly - there is
> no testing at all !
>
> On Mar 18, 2020, at 7:02 AM, Ondrej <ondre...@gmail.com <javascript:>>
> wrote:
>
>
> Hey!
>
> There's an issue I've been grappling with for ages - say I have a custom
> function, Print, that calls six other functions, FormatString, FormatBool,
> FormatXYZ, ..., and I have no tests. Once I write some basic tests for
> Print, it does call some of the other functions and from looking at my test
> coverage, it looks like I have those nested functions covered, but I never
> called them explicitly, I never did try all their corner cases, did not
> fuzz them or anything.
>
> It may sound odd or not important, but I have encountered this in almost
> every project in Go and other languages - the setup is always the same -
> lots of small functions doing their thing and then some orchestrator that
> integrates everything (could be a cli, could be an endpoint etc.) and once
> I set that up, coverage spikes up.
>
> Here's a simple example:
>
> // calculator.go
> package calculator
>
> func Add(a, b int) int {
> return a+b
> }
>
> func Calculator(a, b int) int {
> return Add(a, b)
> }
>
> // calculator_test.go
> package calculator
>
> import "testing"
>
> func TestCalculator(t *testing.T) {
> s := Calculator(1, 2)
> _ = s
> }
>
> In this case, Calculator is covered, and so is Add, but I never tested how
> Add behaves for values close to the int maximum and with other potentially
> dangerous edge cases.
>
> I've though about this over the years a tiny bit and never really found a
> great solution, because it's not really a technical thing, it's more about
> the workflow and attitude to testing.
>
> I prototyped a simple tool that looks up all the exported functions and
> methods in a package and then checks if they are *explicitly* called in our
> tests. This does not guarantee anything, but at least we know they were
> explicitly used, not indirectly called within a different function. The
> prototype does not quite work for methods, because I got kind of lost in
> the go/{parser,ast} indirections. Also reassigning functions as first class
> values and then calling them from a different variable will probably also
> break it.
>
> So it does give a lot of false positives for methods, but should be mostly
> fine for functions.
>
> While it probably does not solve any problems for any people apart from
> me, I'll try and fix the method issues, because I do really need it for my
> own test writing.
>
> Do let me know if there's a better solution to this or if you've
> encountered this and have some thoughts on the topic.
>
> Thanks!
>
> Ondrej
>
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> .
> <main.go>
>
>
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