Add tests for GetAddrHeaderString in msg_test.go

Add unit tests for the GetAddrHeaderString function to verify correct behavior for various header types and address counts. These tests ensure the function correctly handles single and multiple addresses, as well as scenarios with no addresses.

msg_test.go

@@ -2513,6 +2513,135 @@ func TestMsg_GetAddrHeader(t *testing.T) {
 	})
 }
 
+func TestMsg_GetAddrHeaderString(t *testing.T) {
+	t.Run("GetAddrHeaderString with valid address (from)", func(t *testing.T) {
+		message := NewMsg()
+		if message == nil {
+			t.Fatal("message is nil")
+		}
+		if err := message.From("toni.tester@example.com"); err != nil {
+			t.Fatalf("failed to set header: %s", err)
+		}
+		addrheader := message.GetAddrHeaderString(HeaderFrom)
+		if len(addrheader) != 1 {
+			t.Errorf("GetAddrHeaderString: expected 1 address, got: %d", len(addrheader))
+		}
+		if addrheader[0] == "" {
+			t.Fatalf("GetAddrHeaderString: expected address, got empty string")
+		}
+		if addrheader[0] != "<toni.tester@example.com>" {
+			t.Errorf("GetAddrHeaderString: expected address not returned. Want: %s, got: %s",
+				"<toni.tester@example.com>", addrheader[0])
+		}
+	})
+	t.Run("GetAddrHeaderString with valid address (to, cc, bcc)", func(t *testing.T) {
+		var fn func(...string) error
+		for _, tt := range addrHeaderTests {
+			message := NewMsg()
+			if message == nil {
+				t.Fatal("message is nil")
+			}
+
+			switch tt.header {
+			case HeaderFrom:
+				continue
+			case HeaderTo:
+				fn = message.To
+			case HeaderCc:
+				fn = message.Cc
+			case HeaderBcc:
+				fn = message.Bcc
+			default:
+				t.Logf("header %s not supported", tt.header)
+				continue
+			}
+			t.Run(tt.name, func(t *testing.T) {
+				if err := fn("toni.tester@example.com"); err != nil {
+					t.Fatalf("failed to set header: %s", err)
+				}
+				addrheader := message.GetAddrHeaderString(tt.header)
+				if len(addrheader) != 1 {
+					t.Errorf("GetAddrHeaderString: expected 1 address, got: %d", len(addrheader))
+				}
+				if addrheader[0] == "" {
+					t.Fatalf("GetAddrHeaderString: expected address, got empty string")
+				}
+				if addrheader[0] != "<toni.tester@example.com>" {
+					t.Errorf("GetAddrHeaderString: expected address not returned. Want: %s, got: %s",
+						"<toni.tester@example.com>", addrheader[0])
+				}
+			})
+		}
+	})
+	t.Run("GetAddrHeaderString with multiple valid address (to, cc, bcc)", func(t *testing.T) {
+		var fn func(...string) error
+		var addfn func(string) error
+		for _, tt := range addrHeaderTests {
+			message := NewMsg()
+			if message == nil {
+				t.Fatal("message is nil")
+			}
+
+			switch tt.header {
+			case HeaderFrom:
+				continue
+			case HeaderTo:
+				fn = message.To
+				addfn = message.AddTo
+			case HeaderCc:
+				fn = message.Cc
+				addfn = message.AddCc
+			case HeaderBcc:
+				fn = message.Bcc
+				addfn = message.AddBcc
+			default:
+				t.Logf("header %s not supported", tt.header)
+				continue
+			}
+			t.Run(tt.name, func(t *testing.T) {
+				if err := fn("toni.tester@example.com"); err != nil {
+					t.Fatalf("failed to set header: %s", err)
+				}
+				if err := addfn("tina.tester@example.com"); err != nil {
+					t.Fatalf("failed to set additional header value: %s", err)
+				}
+				addrheader := message.GetAddrHeaderString(tt.header)
+				if len(addrheader) != 2 {
+					t.Errorf("GetAddrHeaderString: expected 1 address, got: %d", len(addrheader))
+				}
+				if addrheader[0] == "" {
+					t.Fatalf("GetAddrHeaderString: expected address, got empty string")
+				}
+				if addrheader[0] != "<toni.tester@example.com>" {
+					t.Errorf("GetAddrHeaderString: expected address not returned. Want: %s, got: %s",
+						"<toni.tester@example.com>", addrheader[0])
+				}
+				if addrheader[1] == "" {
+					t.Fatalf("GetAddrHeaderString: expected address, got nil")
+				}
+				if addrheader[1] != "<tina.tester@example.com>" {
+					t.Errorf("GetAddrHeaderString: expected address not returned. Want: %s, got: %s",
+						"<tina.tester@example.com>", addrheader[1])
+				}
+			})
+		}
+	})
+	t.Run("GetAddrHeaderString with no addresses", func(t *testing.T) {
+		message := NewMsg()
+		if message == nil {
+			t.Fatal("message is nil")
+		}
+		for _, tt := range addrHeaderTests {
+			t.Run(tt.name, func(t *testing.T) {
+				addrheader := message.GetAddrHeaderString(HeaderFrom)
+				if len(addrheader) != 0 {
+					t.Errorf("GetAddrHeaderString: expected 0 address, got: %d", len(addrheader))
+				}
+			})
+		}
+	})
+}
+
 // checkAddrHeader verifies the correctness of an AddrHeader in a Msg based on the provided criteria.
 // It checks whether the AddrHeader contains the correct address, name, and number of fields.
 func checkAddrHeader(t *testing.T, message *Msg, header AddrHeader, fn string, field, wantFields int,