[#7] Check empty line after commit's header

Signed-off-by: Ekaterina Lebedeva <ekaterina.lebedeva@yadro.com>

main.go

@@ -19,6 +19,7 @@ var rxHeader = regexp.MustCompile(`^(\[\#[0-9]+\]\s|Release|Revert|Reapply)`)
 func main() {
 	// Prepare regexp templates.
 	rxSignOff := regexp.MustCompile(`^Signed-off-by:`)
+	rxEmptyLine := regexp.MustCompile(`^$`)
 
 	// Open current git dir.
 	r, err := git.PlainOpen("./")
@@ -69,6 +70,13 @@ func main() {
 			return nil
 		}
 
+		// Do not process commits shorter than 3 lines.
+		if len(lines) < 3 {
+			fail = true
+			fmt.Printf("Error: commit is too short [%s]\n", id)
+			return nil
+		}
+
 		// Check commit header.
 		header := lines[0]
 		if !rxHeader.MatchString(header) {
@@ -77,6 +85,13 @@ func main() {
 			return nil
 		}
 
+		// Check empty line after header.
+		if !rxEmptyLine.MatchString(lines[1]) {
+			fail = true
+			fmt.Printf("Error: second line must be empty '%s' [%s]\n", lines[1], id)
+			return nil
+		}
+
 		// Check commit sign-off.
 		if !rxSignOff.MatchString(lines[len(lines)-1]) {
 			fail = true