Separating unit tests and integration tests in Go

Is there an established best practice for separating unit tests and integration tests in GoLang (testify)? I have a mix of unit tests (which do not rely on any external resources and thus run really fast) and integration tests (which do rely on any external resources and thus run slower). So, I want to be able to control whether or not to include the integration tests when I say go test.

The most straight-forward technique would seem to be to define a -integrate flag in main:

var runIntegrationTests = flag.Bool("integration", false
    , "Run the integration tests (in addition to the unit tests)")

And then to add an if-statement to the top of every integration test:

if !*runIntegrationTests {
    this.T().Skip("To run this test, use: go test -integration")
}

Is this the best I can do? I searched the testify documentation to see if there is perhaps a naming convention or something that accomplishes this for me, but didn't find anything. Am I missing something?

@Ainar-G suggests several great patterns to separate tests.

This set of Go practices from SoundCloud recommends using build tags (described in the "Build Constraints" section of the build package) to select which tests to run:

> Write an integration_test.go, and give it a build tag of integration. Define (global) flags for things like service addresses and connect strings, and use them in your tests.
>
> // +build integration
>
> var fooAddr = flag.String(...)
>
> func TestToo(t *testing.T) {
> f, err := foo.Connect(*fooAddr)
> // ...
> }
>
> go test takes build tags just like go build, so you can call go test -tags=integration. It also synthesizes a package main which calls flag.Parse, so any flags declared and visible will be processed and available to your tests.

As a similar option, you could also have integration tests run by default by using a build condition // +build !unit, and then disable them on demand by running go test -tags=unit.

@adamc comments:

For anyone else attempting to use build tags, it's important that the // +build test comment is the first line in your file, and that you include a blank line after the comment, otherwise the -tags command will ignore the directive.

Also, the tag used in the build comment cannot have a dash, although underscores are allowed. For example, // +build unit-tests will not work, whereas // +build unit_tests will.

To elaborate on my comment to @Ainar-G's excellent answer, over the past year I have been using the combination of -short with Integration naming convention to achieve the best of both worlds.

Unit and Integration tests harmony, in the same file

Build flags previously forced me to have multiple files (services_test.go, services_integration_test.go, etc).

Instead, take this example below where the first two are unit tests and I have an integration test at the end:

package services

import "testing"

func TestServiceFunc(t *testing.T) {
    t.Parallel()
    ...
}

func TestInvalidServiceFunc3(t *testing.T) {
    t.Parallel()
    ...
}

func TestPostgresVersionIntegration(t *testing.T) {
    if testing.Short() {
        t.Skip("skipping integration test")
    }
    ...
}

Notice the last test has the convention of:

1. using Integration in the test name.
2. checking if running under -short flag directive.

Basically, the spec goes: "write all tests normally. if it is a long-running tests, or an integration test, follow this naming convention and check for -short to be nice to your peers."

Run only Unit tests:

go test -v -short

this provides you with a nice set of messages like:

=== RUN   TestPostgresVersionIntegration
--- SKIP: TestPostgresVersionIntegration (0.00s)
        service_test.go:138: skipping integration test

Run Integration Tests only:

go test -run Integration

This runs only the integration tests. Useful for smoke testing canaries in production.

Obviously the downside to this approach is if anyone runs go test, without the -short flag, it will default to run all tests - unit and integration tests.

In reality, if your project is large enough to have unit and integration tests, then you most likely are using a Makefile where you can have simple directives to use go test -short in it. Or, just put it in your README.md file and call it the day.

I see three possible solutions. The first is to use the short mode for unit tests. So you would use go test -short with unit tests and the same but without the -short flag to run your integration tests as well. The standard library uses the short mode to either skip long-running tests, or make them run faster by providing simpler data.

The second is to use a convention and call your tests either TestUnitFoo or TestIntegrationFoo and then use the -run testing flag to denote which tests to run. So you would use go test -run 'Unit' for unit tests and go test -run 'Integration' for integration tests.

The third option is to use an environment variable, and get it in your tests setup with os.Getenv. Then you would use simple go test for unit tests and FOO_TEST_INTEGRATION=true go test for integration tests.

I personally would prefer the -short solution since it's simpler and is used in the standard library, so it seems like it's a de facto way of separating/simplifying long-running tests. But the -run and os.Getenv solutions offer more flexibility (more caution is required as well, since regexps are involved with -run).

I was trying to find a solution for the same recently.
These were my criteria:

• The solution must be universal
• No separate package for integration tests
• The separation should be complete (I should be able to run integration tests only)
• No special naming convention for integration tests
• It should work well without additional tooling

The aforementioned solutions (custom flag, custom build tag, environment variables) did not really satisfy all the above criteria, so after a little digging and playing I came up with this solution:

package main

import (
	"flag"
	"regexp"
	"testing"
)

func TestIntegration(t *testing.T) {
	if m := flag.Lookup("test.run").Value.String(); m == "" || !regexp.MustCompile(m).MatchString(t.Name()) {
		t.Skip("skipping as execution was not requested explicitly using go test -run")
	}

	t.Parallel()

	t.Run("HelloWorld", testHelloWorld)
	t.Run("SayHello", testSayHello)
}

The implementation is straightforward and minimal. Although it requires a simple convention for tests, but it's less error prone. Further improvement could be exporting the code to a helper function.

Usage

Run integration tests only across all packages in a project:

go test -v ./... -run ^TestIntegration$

Run all tests (regular and integration):

go test -v ./... -run .\*

Run only regular tests:

go test -v ./...

This solution works well without tooling, but a Makefile or some aliases can make it easier to user. It can also be easily integrated into any IDE that supports running go tests.

The full example can be found here: https://github.com/sagikazarmark/modern-go-application

I encourage you to look at Peter Bourgons approach, it is simple and avoids some problems with the advice in the other answers: https://peter.bourgon.org/blog/2021/04/02/dont-use-build-tags-for-integration-tests.html

There are many downsides to using build tags, short mode or flags, see here.

I would recommend using environment variables with a test helper that can be imported into individual packages:

func IntegrationTest(t *testing.T) {
    t.Helper()
	if os.Getenv("INTEGRATION") == "" {
		t.Skip("skipping integration tests, set environment variable INTEGRATION")
	}
}

In your tests you can now easily call this at the start of your test function:

func TestPostgresQuery(t *testing.T) {
    IntegrationTest(t)
    // ...
}

Why I would not recommend using either -short or flags:

Someone who checks out your repository for the first time should be able to run go test ./... and all tests are passing which is often not the case if this relies on external dependencies.

The problem with the flag package is that it will work until you have integration tests across different packages and some will run flag.Parse() and some will not which will lead to an error like this:

go test ./... -integration
flag provided but not defined: -integration
Usage of /tmp/go-build3903398677/b001/foo.test:

Environment variables appear to be the most flexible, robust and require the least amount of code with no visible downsides.