exchanges/fill: Add test coverage (#1223)

* Fill go test

* Add return error into Update function

* Update exchanges/fill/fill_test.go

Co-authored-by: Scott <gloriousCode@users.noreply.github.com>

* GateIO: Fix websocket trade tests

* GateIO: More test coverage

* GateIO: Options tests

* GateIO: Fix woopsies

* Address nits

* GateIO: Fix nitters

---------

Co-authored-by: Scott <gloriousCode@users.noreply.github.com>
Co-authored-by: Adrian Gallagher <adrian.gallagher@thrasher.io>

exchanges/fill/fill.go

@@ -1,5 +1,10 @@
 package fill
 
+import "errors"
+
+// ErrFeedDisabled is an error that indicates the fill feed is disabled
+var ErrFeedDisabled = errors.New("fill feed disabled")
+
 // Setup sets up the fill processor
 func (f *Fills) Setup(fillsFeedEnabled bool, c chan interface{}) {
 	f.dataHandler = c
@@ -14,9 +19,11 @@ func (f *Fills) Update(data ...Data) error {
 		return nil
 	}
 
-	if f.fillsFeedEnabled {
-		f.dataHandler <- data
+	if !f.fillsFeedEnabled {
+		return ErrFeedDisabled
 	}
 
+	f.dataHandler <- data
+
 	return nil
 }

exchanges/fill/fill_test.go

@@ -0,0 +1,106 @@
+package fill
+
+import (
+	"errors"
+	"testing"
+	"time"
+)
+
+// TestSetup tests the setup function of the Fills struct
+func TestSetup(t *testing.T) {
+	fill := &Fills{}
+	channel := make(chan interface{})
+	fill.Setup(true, channel)
+
+	if fill.dataHandler == nil {
+		t.Error("expected dataHandler to be set")
+	}
+
+	if !fill.fillsFeedEnabled {
+		t.Error("expected fillsFeedEnabled to be true")
+	}
+}
+
+// TestUpdateDisabledFeed tests the Update function when fillsFeedEnabled is false
+func TestUpdateDisabledFeed(t *testing.T) {
+	channel := make(chan interface{}, 1)
+	fill := Fills{dataHandler: channel, fillsFeedEnabled: false}
+
+	// Send a test data to the Update function
+	testData := Data{Timestamp: time.Now(), Price: 15.2, Amount: 3.2}
+	if err := fill.Update(testData); !errors.Is(err, ErrFeedDisabled) {
+		t.Errorf("Expected ErrFeedDisabled, got %v", err)
+	}
+
+	select {
+	case <-channel:
+		t.Errorf("Expected no data on channel, got data")
+	default:
+		// nothing to do
+	}
+}
+
+// TestUpdate tests the Update function of the Fills struct.
+func TestUpdate(t *testing.T) {
+	channel := make(chan interface{}, 1)
+	fill := &Fills{dataHandler: channel, fillsFeedEnabled: true}
+	receivedData := Data{Timestamp: time.Now(), Price: 15.2, Amount: 3.2}
+	if err := fill.Update(receivedData); err != nil {
+		t.Errorf("Update returned error %v", err)
+	}
+
+	select {
+	case data := <-channel:
+		dataSlice, ok := data.([]Data)
+		if !ok {
+			t.Errorf("expected []Data, got %T", data)
+		}
+
+		if len(dataSlice) != 1 || dataSlice[0] != receivedData {
+			t.Errorf("expected data to be sent through channel")
+		}
+	default:
+		t.Errorf("No data sent to channel")
+	}
+}
+
+// TestUpdateNoData tests the Update function with no Data objects
+func TestUpdateNoData(t *testing.T) {
+	channel := make(chan interface{}, 1)
+	fill := &Fills{dataHandler: channel, fillsFeedEnabled: true}
+	if err := fill.Update(); err != nil {
+		t.Errorf("Update returned error %v", err)
+	}
+
+	select {
+	case <-channel:
+		t.Errorf("Expected no data on channel, got data")
+	default:
+		// pass, nothing to do
+	}
+}
+
+// TestUpdateMultipleData tests the Update function with multiple Data objects
+func TestUpdateMultipleData(t *testing.T) {
+	channel := make(chan interface{}, 2)
+	fill := &Fills{dataHandler: channel, fillsFeedEnabled: true}
+	receivedData := Data{Timestamp: time.Now(), Price: 15.2, Amount: 3.2}
+	receivedData2 := Data{Timestamp: time.Now(), Price: 18.2, Amount: 9.0}
+	if err := fill.Update(receivedData, receivedData2); err != nil {
+		t.Errorf("Update returned error %v", err)
+	}
+
+	select {
+	case data := <-channel:
+		dataSlice, ok := data.([]Data)
+		if !ok {
+			t.Errorf("expected []Data, got %T", data)
+		}
+
+		if len(dataSlice) != 2 || dataSlice[0] != receivedData || dataSlice[1] != receivedData2 {
+			t.Errorf("expected data to be sent through channel")
+		}
+	default:
+		t.Errorf("No data sent to channel")
+	}
+}