Add additional tests for postgres driver

driver/driver_test.go

@@ -0,0 +1,21 @@
+package driver_test
+
+import (
+	"github.com/adrianmacneil/dbmate/driver"
+	"github.com/adrianmacneil/dbmate/driver/postgres"
+	"github.com/stretchr/testify/require"
+	"testing"
+)
+
+func TestGet_Postgres(t *testing.T) {
+	drv, err := driver.Get("postgres")
+	require.Nil(t, err)
+	_, ok := drv.(postgres.Driver)
+	require.Equal(t, true, ok)
+}
+
+func TestGet_Error(t *testing.T) {
+	drv, err := driver.Get("foo")
+	require.Equal(t, "Unknown driver: foo", err.Error())
+	require.Nil(t, drv)
+}