From d27234f7e6c1a891fc30626ef334e7b0b7564279 Mon Sep 17 00:00:00 2001
From: Cyrill Schumacher <cyrill@schumacher.fm>
Date: Fri, 5 Mar 2021 16:53:18 +0100
Subject: [PATCH] check for invalid internalIDs

---
 client.go      |  9 ++++++++-
 client_test.go | 28 +++++++++++++++++++++-------
 2 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/client.go b/client.go
index 816d155..f123ba6 100644
--- a/client.go
+++ b/client.go
@@ -71,6 +71,7 @@ type Client struct {
 	doFn              OptionHTTPRequestFn
 	merchants         map[string]OptionMerchant // string = your custom merchant ID
 	currentInternalID string
+	internalIDFound   bool
 }
 
 type Option interface {
@@ -99,7 +100,8 @@ func MakeClient(opts ...Option) (Client, error) {
 			},
 		}).Do
 	}
-
+	// see if we have a default one, otherwise you always have to call WithMerchant.
+	_, c.internalIDFound = c.merchants[""]
 	return c, nil
 }
 
@@ -107,11 +109,16 @@ func MakeClient(opts ...Option) (Client, error) {
 func (c *Client) WithMerchant(internalID string) *Client {
 	c2 := *c
 	c2.currentInternalID = internalID
+	_, c2.internalIDFound = c2.merchants[internalID]
 	return &c2
 }
 
 func (c *Client) do(req *http.Request, v interface{}) error {
 	internalID := c.currentInternalID
+	if !c.internalIDFound {
+		return fmt.Errorf("ClientID %q not found in list of merchants", internalID)
+	}
+
 	req.SetBasicAuth(c.merchants[internalID].MerchantID, c.merchants[internalID].Password)
 	resp, err := c.doFn(req)
 	defer closeResponse(resp)
diff --git a/client_test.go b/client_test.go
index ce182c4..9d915b6 100644
--- a/client_test.go
+++ b/client_test.go
@@ -101,7 +101,7 @@ func TestClient_Initialize(t *testing.T) {
 	)
 	must(t, err)
 
-	rs, err := c.Initialize(context.Background(), datatrans.RequestInitialize{
+	ri := datatrans.RequestInitialize{
 		Currency:       "CHF",
 		RefNo:          "872732",
 		Amount:         1337,
@@ -115,13 +115,27 @@ func TestClient_Initialize(t *testing.T) {
 		CustomFields: map[string]interface{}{
 			"alp": true,
 		},
-	})
-	must(t, err)
-
-	want := &datatrans.ResponseInitialize{TransactionId: "210215103033478409", RawJSONBody: datatrans.RawJSONBody{0x7b, 0x22, 0x74, 0x72, 0x61, 0x6e, 0x73, 0x61, 0x63, 0x74, 0x69, 0x6f, 0x6e, 0x49, 0x64, 0x22, 0x3a, 0x20, 0x22, 0x32, 0x31, 0x30, 0x32, 0x31, 0x35, 0x31, 0x30, 0x33, 0x30, 0x33, 0x33, 0x34, 0x37, 0x38, 0x34, 0x30, 0x39, 0x22, 0x7d}}
-	if !reflect.DeepEqual(rs, want) {
-		t.Error("invalid response")
 	}
+	t.Run("successful request", func(t *testing.T) {
+		rs, err := c.Initialize(context.Background(), ri)
+		must(t, err)
+
+		want := &datatrans.ResponseInitialize{TransactionId: "210215103033478409", RawJSONBody: datatrans.RawJSONBody{0x7b, 0x22, 0x74, 0x72, 0x61, 0x6e, 0x73, 0x61, 0x63, 0x74, 0x69, 0x6f, 0x6e, 0x49, 0x64, 0x22, 0x3a, 0x20, 0x22, 0x32, 0x31, 0x30, 0x32, 0x31, 0x35, 0x31, 0x30, 0x33, 0x30, 0x33, 0x33, 0x34, 0x37, 0x38, 0x34, 0x30, 0x39, 0x22, 0x7d}}
+		if !reflect.DeepEqual(rs, want) {
+			t.Error("invalid response")
+		}
+	})
+
+	t.Run("invalid merchant", func(t *testing.T) {
+		rs, err := c.WithMerchant("sadfasdf").Initialize(context.Background(), ri)
+		if rs != nil {
+			t.Error("response should be nil")
+		}
+		if err == nil {
+			t.Fatal("expected an error")
+		}
+		t.Log(err)
+	})
 }
 
 func TestMarshalJSON(t *testing.T) {