feat(parser): add Comment method to check if a line is a comment

line.go

@@ -6,8 +6,10 @@ import (
 )
 
 const (
-	lf = 10 // linefeed ("\n") character
-	cr = 13 // carriage return ("\r") character
+	lf   = 10 // ASCII linefeed ("\n") character.
+	cr   = 13 // ASCII carriage return ("\r") character.
+	hash = 35 // ASCII hash ("#") character.
+
 )
 
 // Line represents a single line of text defined as; A continuous sequence of
@@ -36,6 +38,18 @@ func (s *Line) Blank() bool {
 	return len(bytes.TrimSpace(s.Content)) == 0
 }
 
+// Comment returns true if line content is a commit comment, where the first
+// non-whitespace character in the line is a hash (#).
+func (s *Line) Comment() bool {
+	trimmed := bytes.TrimSpace(s.Content)
+
+	if len(trimmed) == 0 {
+		return false
+	}
+
+	return trimmed[0] == hash
+}
+
 // Lines is a slice of *Line types with some helper methods attached.
 type Lines []*Line
 

line_test.go

@@ -156,6 +156,99 @@ func TestLine_Blank(t *testing.T) {
 	}
 }
 
+func TestLine_Comment(t *testing.T) {
+	tests := []struct {
+		name string
+		line *Line
+		want bool
+	}{
+		{
+			name: "nil",
+			line: &Line{},
+			want: false,
+		},
+		{
+			name: "empty",
+			line: &Line{
+				Number:  1,
+				Content: []byte(""),
+				Break:   []byte{},
+			},
+			want: false,
+		},
+		{
+			name: "space only",
+			line: &Line{
+				Number:  1,
+				Content: []byte("  "),
+				Break:   []byte{},
+			},
+			want: false,
+		},
+		{
+			name: "tab only",
+			line: &Line{
+				Number:  1,
+				Content: []byte("\t\t"),
+				Break:   []byte{},
+			},
+			want: false,
+		},
+		{
+			name: "spaces and tabs",
+			line: &Line{
+				Number:  1,
+				Content: []byte(" \t "),
+				Break:   []byte{},
+			},
+			want: false,
+		},
+		{
+			name: "text",
+			line: &Line{
+				Number:  1,
+				Content: []byte("foobar"),
+				Break:   []byte{},
+			},
+			want: false,
+		},
+		{
+			name: "beings with hash",
+			line: &Line{
+				Number:  1,
+				Content: []byte("# foo bar"),
+				Break:   []byte{},
+			},
+			want: true,
+		},
+		{
+			name: "beings with hash after whitespace",
+			line: &Line{
+				Number:  1,
+				Content: []byte("  \t  # foo bar"),
+				Break:   []byte{},
+			},
+			want: true,
+		},
+		{
+			name: "has hash in middle of text",
+			line: &Line{
+				Number:  1,
+				Content: []byte("  foo # bar"),
+				Break:   []byte{},
+			},
+			want: false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := tt.line.Comment()
+
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}
+
 func TestNewLines(t *testing.T) {
 	tests := []struct {
 		name    string