go-by-test/wallet/wallet_test.go

package wallet

import "testing"

func TestWallet(t *testing.T) {
	assertBalance := func(t testing.TB, wallet Wallet, want Bitcoin) {
		t.Helper()

		got := wallet.Balance()
		if got != want {
			t.Errorf("got %q, want %q", got, want)
		}
	}

	assertError := func(t testing.TB, got error, want string) {
		t.Helper()

		if got == nil {
			t.Fatal("didn't get an error but wanted one")
		}
		if got.Error() != want {
			t.Errorf("got %q, want %q", got, want)
		}
	}

	t.Run("deposit", func(t *testing.T) {
		wallet := Wallet{}
		wallet.Deposit(10)
		assertBalance(t, wallet, Bitcoin(10))
	})

	t.Run("withdraw", func(t *testing.T) {
		wallet := Wallet{balance: Bitcoin(20)}
		wallet.Withdraw(10)
		assertBalance(t, wallet, Bitcoin(10))
	})

	t.Run("withdraw insufficient funds", func(t *testing.T) {
		startingBalance := Bitcoin(20)
		wallet := Wallet{balance: startingBalance}
		err := wallet.Withdraw(100)

		assertError(t, err, "not enough to withdraw")
		assertBalance(t, wallet, startingBalance)
	})
}