Add additional tests for From and To address handling

Refactor "From" related tests to improve error messages and add tests for the new "FromFormat" function. Introduce new tests to validate the "To" address handling, covering various valid and invalid address scenarios.

msg_test.go

@@ -112,12 +112,12 @@ var (
 		{`hi"@"there@domain.tld`, false},     // Quotes must be dot-seperated
 		{`"<\"@\\".!.#%$@domain.tld`, false}, // Quote is escaped and dot-seperated which would be RFC822 compliant, but not RFC5322 compliant
 		{`hi\ there@domain.tld`, false},      // Spaces must be quoted
-		{`cow@[dead::beef]`, true},           // IPv6 is fine
 		{"hello@tld", true},                  // TLD is enough
 		{`你好@域名.顶级域名`, true},                 // We speak RFC6532
+		{`cow@[dead::beef]`, true},           // IPv6 is fine
+		{"1@[1.101.236.21]", true},           // IPv4 is fine
 		{"1@23456789", true},                 // Hypothetically valid, if somebody registers that TLD
 		{"1@[23456789]", false},              // While 23456789 is decimal for 1.101.236.21 it is not RFC5322 compliant
-		{"1@[1.101.236.21]", true},           // IPv4 is fine
 	}
 )
 
@@ -1065,7 +1065,7 @@ func TestMsg_EnvelopeFrom(t *testing.T) {
 			t.Fatalf("failed to set envelope from, addrHeader field is not set")
 		}
 		if len(addresses) != 1 {
-			t.Errorf("failed to set envelope from, addrHeader value count is: %d, want: 1", len(addresses))
+			t.Fatalf("failed to set envelope from, addrHeader value count is: %d, want: 1", len(addresses))
 		}
 		if addresses[0].Address != "toni.tester@example.com" {
 			t.Errorf("failed to set envelope from, addrHeader value is %s, want: %s", addresses[0].Address,
@@ -1106,25 +1106,25 @@ func TestMsg_EnvelopeFromFormat(t *testing.T) {
 			t.Fatal("message is nil")
 		}
 		if err := message.EnvelopeFromFormat("Toni Tester", "toni.tester@example.com"); err != nil {
-			t.Fatalf("failed to set envelope from: %s", err)
+			t.Fatalf("failed to set envelope From: %s", err)
 		}
 		addresses, ok := message.addrHeader[HeaderEnvelopeFrom]
 		if !ok {
-			t.Fatalf("failed to set envelope from, addrHeader field is not set")
+			t.Fatalf("failed to set envelope From, addrHeader field is not set")
 		}
 		if len(addresses) != 1 {
-			t.Errorf("failed to set envelope from, addrHeader value count is: %d, want: 1", len(addresses))
+			t.Fatalf("failed to set envelope From, addrHeader value count is: %d, want: 1", len(addresses))
 		}
 		if addresses[0].Address != "toni.tester@example.com" {
-			t.Errorf("failed to set envelope from, addrHeader value is %s, want: %s", addresses[0].Address,
+			t.Errorf("failed to set envelope From, addrHeader value is %s, want: %s", addresses[0].Address,
 				"toni.tester@example.com")
 		}
 		if addresses[0].String() != `"Toni Tester" <toni.tester@example.com>` {
-			t.Errorf("failed to set envelope from, addrHeader value is %s, want: %s", addresses[0].String(),
+			t.Errorf("failed to set envelope From, addrHeader value is %s, want: %s", addresses[0].String(),
 				"<toni.tester@example.com>")
 		}
 		if addresses[0].Name != "Toni Tester" {
-			t.Errorf("failed to set envelope from, addrHeader name is %s, want: %s", addresses[0].Name,
+			t.Errorf("failed to set envelope From, addrHeader name is %s, want: %s", addresses[0].Name,
 				"Toni Tester")
 		}
 	})
@@ -1155,25 +1155,25 @@ func TestMsg_From(t *testing.T) {
 			t.Fatal("message is nil")
 		}
 		if err := message.From("toni.tester@example.com"); err != nil {
-			t.Fatalf("failed to set envelope from: %s", err)
+			t.Fatalf("failed to set From: %s", err)
 		}
 		addresses, ok := message.addrHeader[HeaderFrom]
 		if !ok {
-			t.Fatalf("failed to set envelope from, addrHeader field is not set")
+			t.Fatalf("failed to set From, addrHeader field is not set")
 		}
 		if len(addresses) != 1 {
-			t.Errorf("failed to set envelope from, addrHeader value count is: %d, want: 1", len(addresses))
+			t.Fatalf("failed to set From, addrHeader value count is: %d, want: 1", len(addresses))
 		}
 		if addresses[0].Address != "toni.tester@example.com" {
-			t.Errorf("failed to set envelope from, addrHeader value is %s, want: %s", addresses[0].Address,
+			t.Errorf("failed to set From, addrHeader value is %s, want: %s", addresses[0].Address,
 				"toni.tester@example.com")
 		}
 		if addresses[0].String() != "<toni.tester@example.com>" {
-			t.Errorf("failed to set envelope from, addrHeader value is %s, want: %s", addresses[0].String(),
+			t.Errorf("failed to set From, addrHeader value is %s, want: %s", addresses[0].String(),
 				"<toni.tester@example.com>")
 		}
 		if addresses[0].Name != "" {
-			t.Errorf("failed to set envelope from, addrHeader name is %s, want: empty", addresses[0].Name)
+			t.Errorf("failed to set From, addrHeader name is %s, want: empty", addresses[0].Name)
 		}
 	})
 	t.Run("From with invalid address", func(t *testing.T) {
@@ -1194,7 +1194,7 @@ func TestMsg_From(t *testing.T) {
 			t.Fatalf("From should fail with invalid address")
 		}
 	})
-	t.Run("From with different RFC5321 addresses", func(t *testing.T) {
+	t.Run("From with different RFC5322 addresses", func(t *testing.T) {
 		message := NewMsg()
 		if message == nil {
 			t.Fatal("message is nil")
@@ -1213,6 +1213,158 @@ func TestMsg_From(t *testing.T) {
 	})
 }
 
+func TestMsg_FromFormat(t *testing.T) {
+	t.Run("FromFormat with valid address", func(t *testing.T) {
+		message := NewMsg()
+		if message == nil {
+			t.Fatal("message is nil")
+		}
+		if err := message.FromFormat("Toni Tester", "toni.tester@example.com"); err != nil {
+			t.Fatalf("failed to set From: %s", err)
+		}
+		addresses, ok := message.addrHeader[HeaderFrom]
+		if !ok {
+			t.Fatalf("failed to set From, addrHeader field is not set")
+		}
+		if len(addresses) != 1 {
+			t.Fatalf("failed to set From, addrHeader value count is: %d, want: 1", len(addresses))
+		}
+		if addresses[0].Address != "toni.tester@example.com" {
+			t.Errorf("failed to set From, addrHeader value is %s, want: %s", addresses[0].Address,
+				"toni.tester@example.com")
+		}
+		if addresses[0].String() != `"Toni Tester" <toni.tester@example.com>` {
+			t.Errorf("failed to set From, addrHeader value is %s, want: %s", addresses[0].String(),
+				"<toni.tester@example.com>")
+		}
+		if addresses[0].Name != "Toni Tester" {
+			t.Errorf("failed to set From, addrHeader name is %s, want: %s", addresses[0].Name,
+				"Toni Tester")
+		}
+	})
+	t.Run("FromFormat with invalid address", func(t *testing.T) {
+		message := NewMsg()
+		if message == nil {
+			t.Fatal("message is nil")
+		}
+		if err := message.FromFormat("Toni Tester", "invalid"); err == nil {
+			t.Fatalf("FromFormat should fail with invalid address")
+		}
+	})
+	t.Run("FromFormat with empty string should fail", func(t *testing.T) {
+		message := NewMsg()
+		if message == nil {
+			t.Fatal("message is nil")
+		}
+		if err := message.FromFormat("", ""); err == nil {
+			t.Fatalf("FromFormat should fail with invalid address")
+		}
+	})
+}
+
+func TestMsg_To(t *testing.T) {
+	t.Run("To with valid address", func(t *testing.T) {
+		message := NewMsg()
+		if message == nil {
+			t.Fatal("message is nil")
+		}
+		if err := message.To("toni.tester@example.com"); err != nil {
+			t.Fatalf("failed to set To: %s", err)
+		}
+		addresses, ok := message.addrHeader[HeaderTo]
+		if !ok {
+			t.Fatalf("failed to set To, addrHeader field is not set")
+		}
+		if len(addresses) != 1 {
+			t.Fatalf("failed to set To, addrHeader value count is: %d, want: 1", len(addresses))
+		}
+		if addresses[0].Address != "toni.tester@example.com" {
+			t.Errorf("failed to set To, addrHeader value is %s, want: %s", addresses[0].Address,
+				"toni.tester@example.com")
+		}
+		if addresses[0].String() != "<toni.tester@example.com>" {
+			t.Errorf("failed to set To, addrHeader value is %s, want: %s", addresses[0].String(),
+				"<toni.tester@example.com>")
+		}
+		if addresses[0].Name != "" {
+			t.Errorf("failed to set To, addrHeader name is %s, want: empty", addresses[0].Name)
+		}
+	})
+	t.Run("To with multiple valid addresses", func(t *testing.T) {
+		message := NewMsg()
+		if message == nil {
+			t.Fatal("message is nil")
+		}
+		if err := message.To("toni.tester@example.com", "tina.tester@example.com"); err != nil {
+			t.Fatalf("failed to set To: %s", err)
+		}
+		addresses, ok := message.addrHeader[HeaderTo]
+		if !ok {
+			t.Fatalf("failed to set To, addrHeader field is not set")
+		}
+		if len(addresses) != 2 {
+			t.Fatalf("failed to set To, addrHeader value count is: %d, want: 2", len(addresses))
+		}
+		if addresses[0].Address != "toni.tester@example.com" {
+			t.Errorf("failed to set To, addrHeader value is %s, want: %s", addresses[0].Address,
+				"toni.tester@example.com")
+		}
+		if addresses[0].String() != "<toni.tester@example.com>" {
+			t.Errorf("failed to set To, addrHeader value is %s, want: %s", addresses[0].String(),
+				"<toni.tester@example.com>")
+		}
+		if addresses[0].Name != "" {
+			t.Errorf("failed to set To, addrHeader name is %s, want: empty", addresses[0].Name)
+		}
+		if addresses[1].Address != "tina.tester@example.com" {
+			t.Errorf("failed to set To, addrHeader value is %s, want: %s", addresses[0].Address,
+				"tina.tester@example.com")
+		}
+		if addresses[1].String() != "<tina.tester@example.com>" {
+			t.Errorf("failed to set To, addrHeader value is %s, want: %s", addresses[0].String(),
+				"<tina.tester@example.com>")
+		}
+		if addresses[1].Name != "" {
+			t.Errorf("failed to set To, addrHeader name is %s, want: empty", addresses[0].Name)
+		}
+	})
+	t.Run("To with invalid address", func(t *testing.T) {
+		message := NewMsg()
+		if message == nil {
+			t.Fatal("message is nil")
+		}
+		if err := message.To("invalid"); err == nil {
+			t.Fatalf("To should fail with invalid address")
+		}
+	})
+	t.Run("To with empty string should fail", func(t *testing.T) {
+		message := NewMsg()
+		if message == nil {
+			t.Fatal("message is nil")
+		}
+		if err := message.To(""); err == nil {
+			t.Fatalf("To should fail with invalid address")
+		}
+	})
+	t.Run("To with different RFC5322 addresses", func(t *testing.T) {
+		message := NewMsg()
+		if message == nil {
+			t.Fatal("message is nil")
+		}
+		for _, tt := range rfc5322Test {
+			t.Run(tt.value, func(t *testing.T) {
+				err := message.To(tt.value)
+				if err != nil && tt.valid {
+					t.Errorf("To on address %s should succeed, but failed with: %s", tt.value, err)
+				}
+				if err == nil && !tt.valid {
+					t.Errorf("To on address %s should fail, but succeeded", tt.value)
+				}
+			})
+		}
+	})
+}
+
 /*
 // TestNewMsgWithMiddleware tests WithMiddleware