setup and teardown for each test using std testing package

Question

I am using go "testing" package. Running my tests like below.

func TestMain(m *testing.M) {

   ...
   // Setup
   os.Exit(m.Run())
   // Teardown
}

This will run a setup before any test is run, and a teardown after all tests are complete. And I do need this, as the setup sets the DB up. But also, I need, and yet to find out a way to run a per-test setup/teardown. For the unit tests I am running, I would like to clear the DB before every test, so that there are no issues with the content of the DB causing unexpected behavior.

Answer 1

Update for Go 1.14 (Q1 2020)

The testing package now supports cleanup functions, called after a test or benchmark has finished, by calling T.Cleanup or B.Cleanup respectively. Example,

func TestFunction(t *testing.T) {
    // setup code
    t.Cleanup(func(){
        // tear-down code
    })
    // sub-tests
    t.Run() 
    t.Run() 
    ...
}

Here, t.Cleanup runs after the test and all its sub-tests are complete.

---

Original answer (Feb. 2017)
As shown in the article "Go unit test setup and teardown" from Kare Nuorteva, you could use a setup function which returns... a teardown function to you defer.

See this gist:

func setupSubTest(t *testing.T) func(t *testing.T) {
    t.Log("setup sub test")
    return func(t *testing.T) {
        t.Log("teardown sub test")
    }
}

The setup function is in charge of defining and returning the teardown one.

For each test, for instance in a table-driven test scenario:

for _, tc := range cases {
    t.Run(tc.name, func(t *testing.T) {
        teardownSubTest := setupSubTest(t)
        defer teardownSubTest(t)

        result := Sum(tc.a, tc.b)
        if result != tc.expected {
            t.Fatalf("expected sum %v, but got %v", tc.expected, result)
        }
    })
}