More test coverage

Refactored the way EML files are tested, the errors are now handled more efficiently. Temporary directory and file creation, as well as file writing, have been moved to a helper function named 'stringToTempFile'. Moreover, additional test cases were added to ensure proper parsing failure for various types of email-related errors.

eml.go

@@ -39,11 +39,8 @@ func EMLToMsgFromReader(reader io.Reader) (*Msg, error) {
 		return msg, fmt.Errorf("failed to parse EML from reader: %w", err)
 	}
 
-	if err = parseEMLHeaders(&parsedMsg.Header, msg); err != nil {
+	if err := parseEML(parsedMsg, bodybuf, msg); err != nil {
-		return msg, fmt.Errorf("failed to parse EML headers: %w", err)
+		return msg, fmt.Errorf("failed to parse EML contents: %w", err)
-	}
-	if err = parseEMLBodyParts(parsedMsg, bodybuf, msg); err != nil {
-		return msg, fmt.Errorf("failed to parse EML body parts: %w", err)
 	}
 
 	return msg, nil
@@ -64,17 +61,24 @@ func EMLToMsgFromFile(filePath string) (*Msg, error) {
 		return msg, fmt.Errorf("failed to parse EML file: %w", err)
 	}
 
-	if err = parseEMLHeaders(&parsedMsg.Header, msg); err != nil {
+	if err := parseEML(parsedMsg, bodybuf, msg); err != nil {
-		return msg, fmt.Errorf("failed to parse EML headers: %w", err)
+		return msg, fmt.Errorf("failed to parse EML contents: %w", err)
 	}
-	if err = parseEMLBodyParts(parsedMsg, bodybuf, msg); err != nil {
-		return msg, fmt.Errorf("failed to parse EML body parts: %w", err)
-	}
-	//fmt.Printf("FOO: %+v\n", msg)
 
 	return msg, nil
 }
 
+// parseEML parses the EML's headers and body and inserts the parsed values into the Msg
+func parseEML(parsedMsg *netmail.Message, bodybuf *bytes.Buffer, msg *Msg) error {
+	if err := parseEMLHeaders(&parsedMsg.Header, msg); err != nil {
+		return fmt.Errorf("failed to parse EML headers: %w", err)
+	}
+	if err := parseEMLBodyParts(parsedMsg, bodybuf, msg); err != nil {
+		return fmt.Errorf("failed to parse EML body parts: %w", err)
+	}
+	return nil
+}
+
 // readEML opens an EML file and uses net/mail to parse the header and body
 func readEML(filePath string) (*netmail.Message, *bytes.Buffer, error) {
 	fileHandle, err := os.Open(filePath)
@@ -195,6 +199,7 @@ func parseEMLBodyParts(parsedMsg *netmail.Message, bodybuf *bytes.Buffer, msg *M
 			return fmt.Errorf("failed to parse multipart body: %w", err)
 		}
 	default:
+		return fmt.Errorf("failed to parse body, unknown content type: %s", mediatype)
 	}
 	return nil
 }

eml_test.go

@@ -5,6 +5,7 @@
 package mail
 
 import (
+	"bytes"
 	"fmt"
 	"os"
 	"strings"
@@ -31,6 +32,115 @@ This is a test mail. Please do not reply to this. Also this line is very long so
 should be wrapped.
 
 
+Thank your for your business!
+The go-mail team
+
+--
+This is a signature`
+	exampleMailPlainBrokenBody = `Date: Wed, 01 Nov 2023 00:00:00 +0000
+MIME-Version: 1.0
+Message-ID: <1305604950.683004066175.AAAAAAAAaaaaaaaaB@go-mail.dev>
+Subject: Example mail // plain text without encoding
+User-Agent: go-mail v0.4.0 // https://github.com/wneessen/go-mail
+X-Mailer: go-mail v0.4.0 // https://github.com/wneessen/go-mail
+From: "Toni Tester" <go-mail@go-mail.dev>
+To: <go-mail+test@go-mail.dev>
+Cc: <go-mail+cc@go-mail.dev>
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: base64
+
+This plain text body should not be parsed as Base64.
+`
+	exampleMailPlainNoContentType = `Date: Wed, 01 Nov 2023 00:00:00 +0000
+MIME-Version: 1.0
+Message-ID: <1305604950.683004066175.AAAAAAAAaaaaaaaaB@go-mail.dev>
+Subject: Example mail // plain text without encoding
+User-Agent: go-mail v0.4.0 // https://github.com/wneessen/go-mail
+X-Mailer: go-mail v0.4.0 // https://github.com/wneessen/go-mail
+From: "Toni Tester" <go-mail@go-mail.dev>
+To: <go-mail+test@go-mail.dev>
+Cc: <go-mail+cc@go-mail.dev>
+
+This plain text body should not be parsed as Base64.
+`
+	exampleMailPlainUnknownContentType = `Date: Wed, 01 Nov 2023 00:00:00 +0000
+MIME-Version: 1.0
+Message-ID: <1305604950.683004066175.AAAAAAAAaaaaaaaaB@go-mail.dev>
+Subject: Example mail // plain text without encoding
+User-Agent: go-mail v0.4.0 // https://github.com/wneessen/go-mail
+X-Mailer: go-mail v0.4.0 // https://github.com/wneessen/go-mail
+From: "Toni Tester" <go-mail@go-mail.dev>
+To: <go-mail+test@go-mail.dev>
+Cc: <go-mail+cc@go-mail.dev>
+Content-Type: application/unknown; charset=UTF-8
+Content-Transfer-Encoding: base64
+
+This plain text body should not be parsed as Base64.
+`
+	exampleMailPlainBrokenHeader = `Date: Wed, 01 Nov 2023 00:00:00 +0000
+MIME-Version = 1.0
+Message-ID: <1305604950.683004066175.AAAAAAAAaaaaaaaaB@go-mail.dev>
+Subject: Example mail // plain text without encoding
+User-Agent = go-mail v0.4.0 // https://github.com/wneessen/go-mail
+X-Mailer: go-mail v0.4.0 // https://github.com/wneessen/go-mail
+From = "Toni Tester" <go-mail@go-mail.dev>
+To: <go-mail+test@go-mail.dev>
+Cc: <go-mail+cc@go-mail.dev>
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding = 8bit
+
+Dear Customer,
+
+This is a test mail. Please do not reply to this. Also this line is very long so it
+should be wrapped.
+
+
+Thank your for your business!
+The go-mail team
+
+--
+This is a signature`
+	exampleMailPlainBrokenFrom = `Date: Wed, 01 Nov 2023 00:00:00 +0000
+MIME-Version: 1.0
+Message-ID: <1305604950.683004066175.AAAAAAAAaaaaaaaaB@go-mail.dev>
+Subject: Example mail // plain text without encoding
+User-Agent: go-mail v0.4.0 // https://github.com/wneessen/go-mail
+X-Mailer: go-mail v0.4.0 // https://github.com/wneessen/go-mail
+From: Toni Tester" go-mail@go-mail.dev>
+To: <go-mail+test@go-mail.dev>
+Cc: <go-mail+cc@go-mail.dev>
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Dear Customer,
+
+This is a test mail. Please do not reply to this. Also this line is very long so it
+should be wrapped.
+
+
+Thank your for your business!
+The go-mail team
+
+--
+This is a signature`
+	exampleMailPlainBrokenTo = `Date: Wed, 01 Nov 2023 00:00:00 +0000
+MIME-Version: 1.0
+Message-ID: <1305604950.683004066175.AAAAAAAAaaaaaaaaB@go-mail.dev>
+Subject: Example mail // plain text without encoding
+User-Agent: go-mail v0.4.0 // https://github.com/wneessen/go-mail
+X-Mailer: go-mail v0.4.0 // https://github.com/wneessen/go-mail
+From: "Toni Tester" <go-mail@go-mail.dev>
+To: go-mail+test.go-mail.dev>
+Cc: <go-mail+cc@go-mail.dev>
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Dear Customer,
+
+This is a test mail. Please do not reply to this. Also this line is very long so it
+should be wrapped.
+
+
 Thank your for your business!
 The go-mail team
 
@@ -99,6 +209,28 @@ This is a test mail. Please do not reply to this. Also this line is very lo=
 ng so it
 should be wrapped.
 
+Thank your for your business!
+The go-mail team
+
+--
+This is a signature`
+	exampleMailPlainUnsupportedTransferEnc = `Date: Wed, 01 Nov 2023 00:00:00 +0000
+MIME-Version: 1.0
+Message-ID: <1305604950.683004066175.AAAAAAAAaaaaaaaaB@go-mail.dev>
+Subject: Example mail // plain text quoted-printable
+User-Agent: go-mail v0.4.0 // https://github.com/wneessen/go-mail
+X-Mailer: go-mail v0.4.0 // https://github.com/wneessen/go-mail
+From: "Toni Tester" <go-mail@go-mail.dev>
+To: <go-mail+test@go-mail.dev>
+Cc: <go-mail+cc@go-mail.dev>
+Content-Type: text/plain; charset=ISO-8859-1
+Content-Transfer-Encoding: unknown
+
+Dear Customer,
+
+This is a test mail. Please do not reply to this. Also this line is very long so it should be wrapped.
+㋛
+This is not ==D3
 
 Thank your for your business!
 The go-mail team
@@ -151,6 +283,37 @@ VGhpcyBpcyBhIHNpbXBsZSB0ZXN0IHRleHQgZmlsZSBhdHRhY2htZW50LgoKSXQgCiAgaGFzCiAg
 ICAgc2V2ZXJhbAogICAgICAgICAgICBuZXdsaW5lcwoJICAgICAgICAgICAgYW5kCgkgICAgc3Bh
 Y2VzCiAgICAgaW4KICBpdAouCgpBcyB3ZWxsIGFzIGFuIGVtb2ppOiDwn5mCCg==
 
+--45c75ff528359022eb03679fbe91877d75343f2e1f8193e349deffa33ff7--`
+	exampleMailPlainB64BrokenBody = `Date: Wed, 01 Nov 2023 00:00:00 +0000
+MIME-Version: 1.0
+Message-ID: <1305604950.683004066175.AAAAAAAAaaaaaaaaB@go-mail.dev>
+Subject: Example mail // plain text base64 with attachment
+User-Agent: go-mail v0.4.1 // https://github.com/wneessen/go-mail
+X-Mailer: go-mail v0.4.1 // https://github.com/wneessen/go-mail
+From: "Toni Tester" <go-mail@go-mail.dev>
+To: <go-mail+test@go-mail.dev>
+Cc: <go-mail+cc@go-mail.dev>
+Content-Type: multipart/mixed;
+ boundary=45c75ff528359022eb03679fbe91877d75343f2e1f8193e349deffa33ff7
+
+--45c75ff528359022eb03679fbe91877d75343f2e1f8193e349deffa33ff7
+Content-Transfer-Encoding = base64
+Content-Type = text/plain; charset=UTF-8
+
+RGVhciBDdXN0b21lciwKClRoaXMgaXMgYSB0ZXN0IG1haWwuIFBsZWFzZSBkbyBub3QgcmVwbHkg
+dG8gdGhpcy4gQWxzbyB0aGlzIGxpbmUgaXMgdmVyeSBsb25nIHNvIGl0CnNob3VsZCBiZSB3cmFw
+cGVkLgoKClRoYW5rIHlvdXIgZm9yIHlvdXIgYnVzaW5lc3MhClRoZSBnby1tYWlsIHRlYW0KCi0t
+ClRoaXMgaXMgYSBzaWduYXR1cmU=
+
+--45c75ff528359022eb03679fbe91877d75343f2e1f8193e349deffa33ff7
+Content-Disposition: attachment; filename="test.attachment"
+Content-Transfer-Encoding: base64
+Content-Type: application/octet-stream; name="test.attachment"
+
+VGhpcyBpcyBhIHNpbXBsZSB0ZXN0IHRleHQgZmlsZSBhdHRhY2htZW50LgoKSXQgCiAgaGFzCiAg
+ICAgc2V2ZXJhbAogICAgICAgICAgICBuZXdsaW5lcwoJICAgICAgICAgICAgYW5kCgkgICAgc3Bh
+Y2VzCiAgICAgaW4KICBpdAouCgpBcyB3ZWxsIGFzIGFuIGVtb2ppOiDwn5mCCg==
+
 --45c75ff528359022eb03679fbe91877d75343f2e1f8193e349deffa33ff7--`
 	exampleMailPlainB64WithEmbed = `Date: Wed, 01 Nov 2023 00:00:00 +0000
 MIME-Version: 1.0
@@ -240,22 +403,13 @@ func TestEMLToMsgFromFile(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			tempDir, err := os.MkdirTemp("", fmt.Sprintf("*-%s", tt.name))
+			tempDir, tempFile, err := stringToTempFile(tt.eml, tt.name)
-			if err != nil {
-				t.Errorf("failed to create temp dir: %s", err)
-				return
-			}
 			defer func() {
 				if err = os.RemoveAll(tempDir); err != nil {
 					t.Error("failed to remove temp dir:", err)
 				}
 			}()
-			err = os.WriteFile(fmt.Sprintf("%s/%s.eml", tempDir, tt.name), []byte(tt.eml), 0666)
+			msg, err := EMLToMsgFromFile(tempFile)
-			if err != nil {
-				t.Error("failed to write mail to temp file:", err)
-				return
-			}
-			msg, err := EMLToMsgFromFile(fmt.Sprintf("%s/%s.eml", tempDir, tt.name))
 			if err != nil {
 				t.Errorf("failed to parse EML: %s", err)
 			}
@@ -270,6 +424,109 @@ func TestEMLToMsgFromFile(t *testing.T) {
 	}
 }
 
+func TestEMLToMsgFromReaderFailing(t *testing.T) {
+	mailbuf := bytes.NewBufferString(exampleMailPlainBrokenFrom)
+	_, err := EMLToMsgFromReader(mailbuf)
+	if err == nil {
+		t.Error("EML from Reader with broken FROM was supposed to fail, but didn't")
+	}
+	mailbuf.Reset()
+	mailbuf.WriteString(exampleMailPlainBrokenHeader)
+	_, err = EMLToMsgFromReader(mailbuf)
+	if err == nil {
+		t.Error("EML from Reader with broken header was supposed to fail, but didn't")
+	}
+	mailbuf.Reset()
+	mailbuf.WriteString(exampleMailPlainB64BrokenBody)
+	_, err = EMLToMsgFromReader(mailbuf)
+	if err == nil {
+		t.Error("EML from Reader with broken body was supposed to fail, but didn't")
+	}
+	mailbuf.Reset()
+	mailbuf.WriteString(exampleMailPlainBrokenBody)
+	_, err = EMLToMsgFromReader(mailbuf)
+	if err == nil {
+		t.Error("EML from Reader with broken body was supposed to fail, but didn't")
+	}
+	mailbuf.Reset()
+	mailbuf.WriteString(exampleMailPlainUnknownContentType)
+	_, err = EMLToMsgFromReader(mailbuf)
+	if err == nil {
+		t.Error("EML from Reader with unknown content type was supposed to fail, but didn't")
+	}
+	mailbuf.Reset()
+	mailbuf.WriteString(exampleMailPlainNoContentType)
+	_, err = EMLToMsgFromReader(mailbuf)
+	if err == nil {
+		t.Error("EML from Reader with no content type was supposed to fail, but didn't")
+	}
+	mailbuf.Reset()
+	mailbuf.WriteString(exampleMailPlainUnsupportedTransferEnc)
+	_, err = EMLToMsgFromReader(mailbuf)
+	if err == nil {
+		t.Error("EML from Reader with unsupported Transer-Encoding was supposed to fail, but didn't")
+	}
+}
+
+func TestEMLToMsgFromFileFailing(t *testing.T) {
+	tempDir, tempFile, err := stringToTempFile(exampleMailPlainBrokenFrom, "testmail")
+	_, err = EMLToMsgFromFile(tempFile)
+	if err == nil {
+		t.Error("EML from Reader with broken FROM was supposed to fail, but didn't")
+	}
+	if err = os.RemoveAll(tempDir); err != nil {
+		t.Error("failed to remove temp dir:", err)
+	}
+	tempDir, tempFile, err = stringToTempFile(exampleMailPlainBrokenHeader, "testmail")
+	_, err = EMLToMsgFromFile(tempFile)
+	if err == nil {
+		t.Error("EML from Reader with broken header was supposed to fail, but didn't")
+	}
+	if err = os.RemoveAll(tempDir); err != nil {
+		t.Error("failed to remove temp dir:", err)
+	}
+	tempDir, tempFile, err = stringToTempFile(exampleMailPlainB64BrokenBody, "testmail")
+	_, err = EMLToMsgFromFile(tempFile)
+	if err == nil {
+		t.Error("EML from Reader with broken body was supposed to fail, but didn't")
+	}
+	if err = os.RemoveAll(tempDir); err != nil {
+		t.Error("failed to remove temp dir:", err)
+	}
+	tempDir, tempFile, err = stringToTempFile(exampleMailPlainBrokenBody, "testmail")
+	_, err = EMLToMsgFromFile(tempFile)
+	if err == nil {
+		t.Error("EML from Reader with broken body was supposed to fail, but didn't")
+	}
+	if err = os.RemoveAll(tempDir); err != nil {
+		t.Error("failed to remove temp dir:", err)
+	}
+	tempDir, tempFile, err = stringToTempFile(exampleMailPlainUnknownContentType, "testmail")
+	_, err = EMLToMsgFromFile(tempFile)
+	if err == nil {
+		t.Error("EML from Reader with unknown content type was supposed to fail, but didn't")
+	}
+	if err = os.RemoveAll(tempDir); err != nil {
+		t.Error("failed to remove temp dir:", err)
+	}
+	tempDir, tempFile, err = stringToTempFile(exampleMailPlainNoContentType, "testmail")
+	_, err = EMLToMsgFromFile(tempFile)
+	if err == nil {
+		t.Error("EML from Reader with no content type was supposed to fail, but didn't")
+	}
+	if err = os.RemoveAll(tempDir); err != nil {
+		t.Error("failed to remove temp dir:", err)
+	}
+	tempDir, tempFile, err = stringToTempFile(exampleMailPlainUnsupportedTransferEnc, "testmail")
+	_, err = EMLToMsgFromFile(tempFile)
+	if err == nil {
+		t.Error("EML from Reader with unsupported Transer-Encoding was supposed to fail, but didn't")
+	}
+	if err = os.RemoveAll(tempDir); err != nil {
+		t.Error("failed to remove temp dir:", err)
+	}
+}
+
 func TestEMLToMsgFromStringBrokenDate(t *testing.T) {
 	_, err := EMLToMsgFromString(exampleMailPlainNoEncInvalidDate)
 	if err == nil {
@@ -291,6 +548,20 @@ func TestEMLToMsgFromStringBrokenDate(t *testing.T) {
 	}
 }
 
+func TestEMLToMsgFromStringBrokenFrom(t *testing.T) {
+	_, err := EMLToMsgFromString(exampleMailPlainBrokenFrom)
+	if err == nil {
+		t.Error("EML with broken FROM was supposed to fail, but didn't")
+	}
+}
+
+func TestEMLToMsgFromStringBrokenTo(t *testing.T) {
+	_, err := EMLToMsgFromString(exampleMailPlainBrokenTo)
+	if err == nil {
+		t.Error("EML with broken TO was supposed to fail, but didn't")
+	}
+}
+
 func TestEMLToMsgFromStringWithAttachment(t *testing.T) {
 	wantSubject := "Example mail // plain text base64 with attachment"
 	msg, err := EMLToMsgFromString(exampleMailPlainB64WithAttachment)
@@ -322,3 +593,17 @@ func TestEMLToMsgFromStringWithEmbed(t *testing.T) {
 			1, len(msg.attachments))
 	}
 }
+
+// stringToTempFile is a helper method that will create a temporary file form a give data string
+func stringToTempFile(data, name string) (string, string, error) {
+	tempDir, err := os.MkdirTemp("", fmt.Sprintf("*-%s", name))
+	if err != nil {
+		return tempDir, "", fmt.Errorf("failed to create temp dir: %w", err)
+	}
+	filePath := fmt.Sprintf("%s/%s", tempDir, name)
+	err = os.WriteFile(filePath, []byte(data), 0666)
+	if err != nil {
+		return tempDir, "", fmt.Errorf("failed to write data to temp file: %w", err)
+	}
+	return tempDir, filePath, nil
+}