Config: Refactor version packages (#1887)

* Config: Move config versions to separate pacakges

* Config: Move version tests to blackbox texts

* Config: Protect registerVersion from overflow

* Config: Protect against version already registered

config/versions/v2/v2_test.go

@@ -0,0 +1,38 @@
+package v2_test
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	v2 "github.com/thrasher-corp/gocryptotrader/config/versions/v2"
+)
+
+func TestUpgradeExchange(t *testing.T) {
+	t.Parallel()
+	for _, tt := range [][]string{
+		{"GDAX", "CoinbasePro"},
+		{"Kraken", "Kraken"},
+		{"CoinbasePro", "CoinbasePro"},
+	} {
+		out, err := new(v2.Version).UpgradeExchange(context.Background(), []byte(`{"name":"`+tt[0]+`"}`))
+		require.NoError(t, err)
+		require.NotEmpty(t, out)
+		assert.Equalf(t, `{"name":"`+tt[1]+`"}`, string(out), "Test exchange name %s", tt[0])
+	}
+}
+
+func TestDowngradeExchange(t *testing.T) {
+	t.Parallel()
+	for _, tt := range [][]string{
+		{"GDAX", "GDAX"},
+		{"Kraken", "Kraken"},
+		{"CoinbasePro", "GDAX"},
+	} {
+		out, err := new(v2.Version).DowngradeExchange(context.Background(), []byte(`{"name":"`+tt[0]+`"}`))
+		require.NoError(t, err)
+		require.NotEmpty(t, out)
+		assert.Equalf(t, `{"name":"`+tt[1]+`"}`, string(out), "Test exchange name %s", tt[0])
+	}
+}