Hello, I am trying out golang and like it's concepts (coming from Python and Java mostly, not having Exceptions felt a bit strange at the start, though :-)).
* Now I try to write tests for https://github.com/caradojo/trivia/blob/master/go/trivia.go for the fun of it. * I want to do this without modifying the code (too much). * I already introduced my own fake[1] random and now need to replace os.Stdout with a fake implementation as the results of the game implemented here are written with `fmt.Println` resp. `fmt.Printf`. * My first approach was to use a tempfile[2], this works but I do not like to touch the disk during tests. * In Java `System.out` is just a `PrintStream` which is easily replaced by sth. like `System.setOut(new PrintStream(new ByteArrayOutputStream()));` * Now in golang `os.Stdout` is an `*os.File` which is mostly a wrapper for an OS specific file. I now tried something like this: ``` type file interface { io.Writer } type fakeFile struct { out *bytes.Buffer } func (ff fakeFile) Write(p []byte) (n int, err error) { return ff.out.Write(p) } func foo() realStdout := os.Stdout defer func() { os.Stdout = realStdout }() var out []byte var f file = fakeFile{bytes.NewBuffer(out)} os.Stdout = &os.File{&f} ) ``` This does not compile but I get "cannot use &f (type *file) as type *os.file in field value". Then I tried a Pythonesque approach, something like this: ``` realStdoutWrite := os.Stdout.Write defer func() { os.Stdout.Write = realStdoutWrite }() var outb = bytes.NewBufferString("") os.Stdout.Write = outb.Write ``` but get "cannot assign to os.Stdout.Write" In a real world example I would not write to os.Stdout but inject an `io.Writer` which would be used, so this is more a question whether I miss something or is faking os.Stdout really hard? Any hints appreciated :-) Regards Mirko [1] https://martinfowler.com/articles/mocksArentStubs.html#TheDifferenceBetweenMocksAndStubs [2] https://github.com/mfriedenhagen/trivia/commit/b8ecec0097bfb4a6e7e2992e1401274cff06c03b#diff-2a08ba5d9ea423f34350a051d2333274R44 -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
