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

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

go.mod

@@ -5,6 +5,7 @@ go 1.20
 require (
 	github.com/go-git/go-git/v5 v5.7.0
 	github.com/sethvargo/go-githubactions v1.1.0
+	github.com/stretchr/testify v1.4.0
 )
 
 require (
@@ -12,6 +13,7 @@ require (
 	github.com/ProtonMail/go-crypto v0.0.0-20230518184743-7afd39499903 // indirect
 	github.com/acomagu/bufpipe v1.0.4 // indirect
 	github.com/cloudflare/circl v1.3.3 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/emirpasic/gods v1.18.1 // indirect
 	github.com/go-git/gcfg v1.5.1-0.20230307220236-3a3c6141e376 // indirect
 	github.com/go-git/go-billy/v5 v5.4.1 // indirect
@@ -20,6 +22,7 @@ require (
 	github.com/jbenet/go-context v0.0.0-20150711004518-d14ea06fba99 // indirect
 	github.com/kevinburke/ssh_config v1.2.0 // indirect
 	github.com/pjbgf/sha1cd v0.3.0 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/sergi/go-diff v1.1.0 // indirect
 	github.com/sethvargo/go-envconfig v0.8.0 // indirect
 	github.com/skeema/knownhosts v1.1.1 // indirect
@@ -28,4 +31,5 @@ require (
 	golang.org/x/net v0.10.0 // indirect
 	golang.org/x/sys v0.8.0 // indirect
 	gopkg.in/warnings.v0 v0.1.2 // indirect
+	gopkg.in/yaml.v2 v2.2.4 // indirect
 )

main.go

@@ -14,9 +14,10 @@ import (
 	gha "github.com/sethvargo/go-githubactions"
 )
 
+var rxHeader = regexp.MustCompile(`^(\[\#[0-9]+\]\s|Release|Revert|Reapply)`)
+
 func main() {
 	// Prepare regexp templates.
-	rxHeader := regexp.MustCompile(`^(\[\#[0-9Xx]+\]\s|Release)`)
 	rxSignOff := regexp.MustCompile(`^Signed-off-by:`)
 
 	// Open current git dir.
@@ -76,6 +77,13 @@ func main() {
 			return nil
 		}
 
+		// Check empty line after header.
+		if 1 < len(lines) && 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

main_test.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestCommitMessages(t *testing.T) {
+	allowed := []string{
+		"[#1] omg: Make a commit",
+		"[#666] Omit component",
+		`Revert "[#114] local: Fix payload type after recent refactoring"`,
+		`Reapply "[#114] local: Fix payload type after recent refactoring"`,
+		`Release v0.4.2`,
+	}
+
+	for i := range allowed {
+		assert.True(t, rxHeader.MatchString(allowed[i]), "message: '%s'", allowed[i])
+	}
+
+	restricted := []string{
+		"[#xx] omg: Forget numbers",
+		"#12 Forget brackets",
+		"Refactor something",
+	}
+	for i := range restricted {
+		assert.False(t, rxHeader.MatchString(restricted[i]), "message: '%s'", restricted[i])
+	}
+}