如何在测试中构建程序

Question

I want to test, that a function callProgram executes a binary and handles the output correctly. For that my initial thought would be to compile raw code like:

package mytest

import (
    "testing"
)

const (
    binary_code = `
       package main

       func main() {
           // Glorious processing ...
       }
    `
)

func TestCall(t *testing.T) {
    p := buildTestProgram(binary_code, "~/testbinary")
    defer p.Delete()
    callProgram("~/testbinary")
}

I looked into the build command (runBuild) and its' implementation is sufficiently easy. Problem is, that it lives in the internal namespace and cmd/go does not seem to expose any way of calling runBuild or similar.

So my question is how to test a certain binary and also having to interact with the hosting system as little as possible.

Yes, I could download a prebuilt binary, execute go build, etc. but I would be really glad to minimize the chances of potential errors/complexity and also be as portable as possible.

Answer 1

There is no public compiler API.

The easiest way to test you app would be to call / run an existing binary on the system.

If you don't want to rely on this, another option is to have your test create / write a binary file into a temporary folder, test your function and then remove the temporary file. This can be done easily / automatically using the ioutil.TempFile() function.

Creating this temporary binary may or may not be a Go compiling process. Since this is part of a Go test, the Go SDK should already be installed in your system, so calling go shouldn't be a problem.

Your test may also self-contain the content of a tiny, runnable executable which the test could "dump" to a temporary file. Such tiny binaries may be as small as 100 bytes, for an example, see Smallest x86 ELF Hello World. For how to bundle data into a Go app, see What's the best way to bundle static resources in a Go program?