feat: Refactor message handling and update dependencies

- Added required packages to go.mod: `github.com/Laisky/errors/v2 v2.0.1`, `github.com/stretchr/testify v1.8.3`, `github.com/davecgh/go-spew v1.1.1`, `github.com/pmezard/go-difflib v1.0.0`
- Increased the number of returned recordings to 100 in `relay-utils.go`
- Refactored and simplified code in `relay-aiproxy.go` for improved message retrieval and error handling
- Added new test file `relay_test.go` and various test cases for different message types
- Modified functions in `group.go` and `relay.go` for improved functionality

controller/relay_test.go

@@ -0,0 +1,61 @@
+package controller
+
+import (
+	"encoding/json"
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestGeneralOpenAIRequest_TextMessages(t *testing.T) {
+	tests := []struct {
+		name     string
+		messages interface{}
+		want     []Message
+		wantErr  error
+	}{
+		{
+			name:     "Test with []any messages",
+			messages: []any{Message{}, Message{}},
+			want:     []Message{{}, {}},
+			wantErr:  nil,
+		},
+		{
+			name:     "Test with []Message messages",
+			messages: []Message{{}, {}},
+			want:     []Message{{}, {}},
+			wantErr:  nil,
+		},
+		{
+			name:     "Test with invalid message type",
+			messages: "invalid",
+			want:     nil,
+			wantErr:  fmt.Errorf("invalid message type string"),
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			r := &GeneralOpenAIRequest{
+				Messages: tt.messages,
+			}
+			got := new(GeneralOpenAIRequest)
+
+			blob, err := json.Marshal(r)
+			require.NoError(t, err)
+			err = json.Unmarshal(blob, got)
+			require.NoError(t, err)
+
+			gotMessages, err := got.TextMessages()
+			if tt.wantErr != nil {
+				require.ErrorContains(t, err, "cannot unmarshal string into Go value")
+				return
+			} else {
+				require.NoError(t, err)
+			}
+
+			require.Equal(t, tt.want, gotMessages)
+		})
+	}
+}