...

func TestSnippetCreate(t *testing.T) {
    app := newTestApplication(t)
    ts := newTestServer(t, app.routes())
    defer ts.Close()
}

...

func TestSnippetCreate(t *testing.T) {
    app := newTestApplication(t)
    ts := newTestServer(t, app.routes())
    defer ts.Close()

    t.Run("Unauthenticated", func(t *testing.T) {
        code, headers, _ := ts.get(t, "/snippet/create")
        
        assert.Equal(t, code,  http.StatusSeeOther)
        assert.Equal(t, headers.Get("Location"), "/user/login")
    })
}

...

func TestSnippetCreate(t *testing.T) {
    app := newTestApplication(t)
    ts := newTestServer(t, app.routes())
    defer ts.Close()

    t.Run("Unauthenticated", func(t *testing.T) {
        code, headers, _ := ts.get(t, "/snippet/create")
        
        assert.Equal(t, code,  http.StatusSeeOther)
        assert.Equal(t, headers.Get("Location"), "/user/login")
    })
    
    t.Run("Authenticated", func(t *testing.T) {
        // Make a GET /user/login request and extract the CSRF token from the
        // response.
        _, _, body := ts.get(t, "/user/login")
        csrfToken := extractCSRFToken(t, body)

        // Make a POST /user/login request using the extracted CSRF token and
        // credentials from our the mock user model.
        form := url.Values{}
        form.Add("email", "alice@example.com")
        form.Add("password", "pa$$word")
        form.Add("csrf_token", csrfToken)
        ts.postForm(t, "/user/login", form)

        // Then check that the authenticated user is shown the create snippet
        // form.
        code, _, body := ts.get(t, "/snippet/create")
        
        assert.Equal(t, code,  http.StatusOK)
        assert.StringContains(t, body, "<form action='/snippet/create' method='POST'>")
    })
}