isolate record reading and writing from processing

internal/stdout_test.go

@@ -0,0 +1,93 @@
+package internal_test
+
+import (
+	"bytes"
+	"fmt"
+	"math/big"
+	"testing"
+	"time"
+
+	"git.naterciomoniz.net/applications/broker2anexoj/internal"
+)
+
+func TestReportLogger_Write(t *testing.T) {
+	tNow := time.Now()
+
+	tests := []struct {
+		name  string
+		items []internal.ReportItem
+		want  []string
+	}{
+		{
+			name: "empty",
+		},
+		{
+			name: "single item positive",
+			items: []internal.ReportItem{
+				{
+					BuyValue:      new(big.Float).SetFloat64(100.0),
+					SellValue:     new(big.Float).SetFloat64(200.0),
+					SellTimestamp: tNow,
+				},
+			},
+			want: []string{
+				fmt.Sprintf("%6d - realised +100.000000 on %s\n", 1, tNow.Format(time.RFC3339)),
+			},
+		},
+		{
+			name: "single item negative",
+			items: []internal.ReportItem{
+				{
+					BuyValue:      new(big.Float).SetFloat64(200.0),
+					SellValue:     new(big.Float).SetFloat64(150.0),
+					SellTimestamp: tNow,
+				},
+			},
+			want: []string{
+				fmt.Sprintf("%6d - realised -50.000000 on %s\n", 1, tNow.Format(time.RFC3339)),
+			},
+		},
+		{
+			name: "multiple items",
+			items: []internal.ReportItem{
+				{
+					BuyValue:      new(big.Float).SetFloat64(100.0),
+					SellValue:     new(big.Float).SetFloat64(200.0),
+					SellTimestamp: tNow,
+				},
+				{
+					BuyValue:      new(big.Float).SetFloat64(200.0),
+					SellValue:     new(big.Float).SetFloat64(150.0),
+					SellTimestamp: tNow.Add(1),
+				},
+			},
+			want: []string{
+				fmt.Sprintf("%6d - realised +100.000000 on %s\n", 1, tNow.Format(time.RFC3339)),
+				fmt.Sprintf("%6d - realised -50.000000 on %s\n", 2, tNow.Add(1).Format(time.RFC3339)),
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			buf := new(bytes.Buffer)
+			rw := internal.NewReportLogger(buf)
+
+			for _, item := range tt.items {
+				err := rw.Write(item)
+				if err != nil {
+					t.Fatalf("unexpected error on write: %v", err)
+				}
+			}
+
+			for _, wantLine := range tt.want {
+				gotLine, err := buf.ReadString(byte('\n'))
+				if err != nil {
+					t.Fatalf("unexpected error on buffer read: %v", err)
+				}
+				if wantLine != gotLine {
+					t.Fatalf("want line %q but got %q", wantLine, gotLine)
+				}
+			}
+		})
+	}
+}