test: test bullet

list/enumerations.go

@@ -49,14 +49,9 @@ const (
 )
 
 func (l *List) bullet(index int) string {
-	// out of bounds?
-	if index < 0 || index >= len(l.items) {
-		return ""
-	}
-
 	switch l.enumeration {
 	case Alphabet:
-		return fmt.Sprintf("%c. ", 'A'+index)
+		return fmt.Sprintf("%s. ", alphabet(index))
 	case Arabic:
 		return fmt.Sprintf("%d. ", index+1)
 	case Roman:
@@ -69,6 +64,15 @@ func (l *List) bullet(index int) string {
 	return ""
 }
 
+const alphabetLength = 26
+
+func alphabet(index int) string {
+	if index >= alphabetLength {
+		return fmt.Sprintf("%c%c", 'A'+index/alphabetLength-1, 'A'+index%alphabetLength)
+	}
+	return fmt.Sprintf("%c", 'A'+index%alphabetLength)
+}
+
 func roman(n int) string {
 	var (
 		roman = []string{"M", "CM", "D", "CD", "C", "XC", "L", "XL",

list/list_test.go

@@ -187,3 +187,32 @@ III. Baz
 		}
 	}
 }
+
+func TestBullet(t *testing.T) {
+	tests := []struct {
+		enum Enumeration
+		i    int
+		exp  string
+	}{
+		{Alphabet, 0, "A. "},
+		{Alphabet, 25, "Z. "},
+		{Alphabet, 26, "AA. "},
+		{Alphabet, 50, "AY. "},
+		{Alphabet, 100, "CW. "},
+		{Alphabet, 701, "ZZ. "},
+		{Roman, 0, "I. "},
+		{Roman, 25, "XXVI. "},
+		{Roman, 26, "XXVII. "},
+		{Roman, 50, "LI. "},
+		{Roman, 100, "CI. "},
+		{Roman, 701, "DCCII. "},
+		{Roman, 1000, "MI. "},
+	}
+
+	for _, test := range tests {
+		bullet := New().Enumeration(test.enum).bullet(test.i)
+		if bullet != test.exp {
+			t.Errorf("expected: %s, got: %s\n", test.exp, bullet)
+		}
+	}
+}