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_test.go

@@ -403,22 +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)
 			}
@@ -434,50 +425,108 @@ func TestEMLToMsgFromFile(t *testing.T) {
 }
 
 func TestEMLToMsgFromReaderFailing(t *testing.T) {
-	mailbuf := bytes.Buffer{}
+	mailbuf := bytes.NewBufferString(exampleMailPlainBrokenFrom)
-	mailbuf.WriteString(exampleMailPlainBrokenFrom)
+	_, err := EMLToMsgFromReader(mailbuf)
-	_, 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)
+	_, 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)
+	_, 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)
+	_, 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)
+	_, 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)
+	_, 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)
+	_, 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 {
@@ -544,3 +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
+}