added Go variant

- using homegrown approval test function

go/theatre/StatementPrinter_test.go

@@ -0,0 +1,74 @@
+package theatre_test
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/emilybache/Theatrical-Players-Refactoring-Kata/go/theatre"
+)
+
+func TestPrinterPrintByApproval(t *testing.T) {
+	verify(t, "json", "txt", func(t testing.TB, data []byte) []byte {
+		var in struct {
+			Plays []struct {
+				ID   string
+				Play struct {
+					Name string
+					Type string
+				}
+			}
+			Invoice struct {
+				Customer     string
+				Performances []struct {
+					PlayID   string
+					Audience int
+				}
+			}
+		}
+
+		if err := json.Unmarshal(data, &in); err != nil {
+			t.Fatalf("failed to unmarshal input data: %v", err)
+			return nil
+		}
+
+		// copy test-structure to production structure. Making use of matching types.
+		plays := make(map[string]theatre.Play)
+		invoice := theatre.Invoice{
+			Customer:     in.Invoice.Customer,
+			Performances: make([]theatre.Performance, 0, len(in.Invoice.Performances)),
+		}
+		for _, perf := range in.Invoice.Performances {
+			invoice.Performances = append(invoice.Performances, perf)
+		}
+		for _, identifiedPlay := range in.Plays {
+			plays[identifiedPlay.ID] = identifiedPlay.Play
+		}
+
+		var printer theatre.StatementPrinter
+		statement, err := printer.Print(invoice, plays)
+		if err != nil {
+			t.Fatalf("failed to create statement, unexpected error: %v", err)
+		}
+		return []byte(statement)
+	})
+}
+
+func TestStatementWithNewPlayTypes(t *testing.T) {
+	plays := map[string]theatre.Play{
+		"henry-v": {Name: "Henry V", Type: "history"},
+		"as-like": {Name: "As You Like It", Type: "pastoral"},
+	}
+	invoice := theatre.Invoice{
+		Customer: "BigCo",
+		Performances: []theatre.Performance{
+			{PlayID: "henry-v", Audience: 53},
+			{PlayID: "as-like", Audience: 55},
+		},
+	}
+
+	var printer theatre.StatementPrinter
+	_, err := printer.Print(invoice, plays)
+	if err == nil {
+		t.Errorf("Expected an error, got none")
+	}
+}