parser: add some frontmatter test cases

parser/frontmatter_test.go

@@ -0,0 +1,25 @@
+package parser
+
+import (
+	"testing"
+)
+
+func TestFormatToLeadRune(t *testing.T) {
+	for i, this := range []struct {
+		kind   string
+		expect rune
+	}{
+		{"yaml", '-'},
+		{"yml", '-'},
+		{"toml", '+'},
+		{"json", '{'},
+		{"js", '{'},
+		{"unknown", '+'},
+	} {
+		result := FormatToLeadRune(this.kind)
+
+		if result != this.expect {
+			t.Errorf("[%d] Got %q but expected %q", i, result, this.expect)
+		}
+	}
+}