This is the v1 version, had the v2 before.

backend/backendutil/body_test.go

@@ -0,0 +1,196 @@
+package backendutil
+
+import (
+	"bufio"
+	"io/ioutil"
+	"strings"
+	"testing"
+
+	"github.com/emersion/go-imap"
+	"github.com/emersion/go-message/textproto"
+)
+
+var bodyTests = []struct {
+	section string
+	body    string
+}{
+	{
+		section: "BODY[]",
+		body:    testMailString,
+	},
+	{
+		section: "BODY[1.1]",
+		body:    testTextBodyString,
+	},
+	{
+		section: "BODY[1.2]",
+		body:    testHTMLBodyString,
+	},
+	{
+		section: "BODY[2]",
+		body:    testAttachmentBodyString,
+	},
+	{
+		section: "BODY[HEADER]",
+		body:    testHeaderString,
+	},
+	{
+		section: "BODY[HEADER.FIELDS (From To)]",
+		body:    testHeaderFromToString,
+	},
+	{
+		section: "BODY[HEADER.FIELDS (FROM to)]",
+		body:    testHeaderFromToString,
+	},
+	{
+		section: "BODY[HEADER.FIELDS.NOT (From To)]",
+		body:    testHeaderNoFromToString,
+	},
+	{
+		section: "BODY[HEADER.FIELDS (Date)]",
+		body:    testHeaderDateString,
+	},
+	{
+		section: "BODY[1.1.HEADER]",
+		body:    testTextHeaderString,
+	},
+	{
+		section: "BODY[1.1.HEADER.FIELDS (Content-Type)]",
+		body:    testTextContentTypeString,
+	},
+	{
+		section: "BODY[1.1.HEADER.FIELDS.NOT (Content-Type)]",
+		body:    testTextNoContentTypeString,
+	},
+	{
+		section: "BODY[2.HEADER]",
+		body:    testAttachmentHeaderString,
+	},
+	{
+		section: "BODY[2.MIME]",
+		body:    testAttachmentHeaderString,
+	},
+	{
+		section: "BODY[TEXT]",
+		body:    testBodyString,
+	},
+	{
+		section: "BODY[1.1.TEXT]",
+		body:    testTextBodyString,
+	},
+	{
+		section: "BODY[2.TEXT]",
+		body:    testAttachmentBodyString,
+	},
+	{
+		section: "BODY[2.1]",
+		body:    "",
+	},
+	{
+		section: "BODY[3]",
+		body:    "",
+	},
+	{
+		section: "BODY[2.TEXT]<0.9>",
+		body:    testAttachmentBodyString[:9],
+	},
+}
+
+func TestFetchBodySection(t *testing.T) {
+	for _, test := range bodyTests {
+		test := test
+		t.Run(test.section, func(t *testing.T) {
+			bufferedBody := bufio.NewReader(strings.NewReader(testMailString))
+
+			header, err := textproto.ReadHeader(bufferedBody)
+			if err != nil {
+				t.Fatal("Expected no error while reading mail, got:", err)
+			}
+
+			section, err := imap.ParseBodySectionName(imap.FetchItem(test.section))
+			if err != nil {
+				t.Fatal("Expected no error while parsing body section name, got:", err)
+			}
+
+			r, err := FetchBodySection(header, bufferedBody, section)
+			if test.body == "" {
+				if err == nil {
+					t.Error("Expected an error while extracting non-existing body section")
+				}
+			} else {
+				if err != nil {
+					t.Fatal("Expected no error while extracting body section, got:", err)
+				}
+
+				b, err := ioutil.ReadAll(r)
+				if err != nil {
+					t.Fatal("Expected no error while reading body section, got:", err)
+				}
+
+				if s := string(b); s != test.body {
+					t.Errorf("Expected body section %q to be \n%s\n but got \n%s", test.section, test.body, s)
+				}
+			}
+		})
+	}
+}
+
+func TestFetchBodySection_NonMultipart(t *testing.T) {
+	// https://tools.ietf.org/html/rfc3501#page-55:
+	//  Every message has at least one part number.  Non-[MIME-IMB]
+	//  messages, and non-multipart [MIME-IMB] messages with no
+	//  encapsulated message, only have a part 1.
+
+	testMsgHdr := "From: Mitsuha Miyamizu <mitsuha.miyamizu@example.org>\r\n" +
+		"To: Taki Tachibana <taki.tachibana@example.org>\r\n" +
+		"Subject: Your Name.\r\n" +
+		"Message-Id: 42@example.org\r\n" +
+		"\r\n"
+	testMsgBody := "That's not multipart message. Thought it should be possible to get this text using BODY[1]."
+	testMsg := testMsgHdr + testMsgBody
+
+	tests := []struct {
+		section string
+		body    string
+	}{
+		{
+			section: "BODY[1.MIME]",
+			body:    testMsgHdr,
+		},
+		{
+			section: "BODY[1]",
+			body:    testMsgBody,
+		},
+	}
+
+	for _, test := range tests {
+		test := test
+		t.Run(test.section, func(t *testing.T) {
+			bufferedBody := bufio.NewReader(strings.NewReader(testMsg))
+
+			header, err := textproto.ReadHeader(bufferedBody)
+			if err != nil {
+				t.Fatal("Expected no error while reading mail, got:", err)
+			}
+
+			section, err := imap.ParseBodySectionName(imap.FetchItem(test.section))
+			if err != nil {
+				t.Fatal("Expected no error while parsing body section name, got:", err)
+			}
+
+			r, err := FetchBodySection(header, bufferedBody, section)
+			if err != nil {
+				t.Fatal("Expected no error while extracting body section, got:", err)
+			}
+
+			b, err := ioutil.ReadAll(r)
+			if err != nil {
+				t.Fatal("Expected no error while reading body section, got:", err)
+			}
+
+			if s := string(b); s != test.body {
+				t.Errorf("Expected body section %q to be \n%s\n but got \n%s", test.section, test.body, s)
+			}
+		})
+	}
+}