Add another memory test just to be sure

parse_test.go

@@ -123,10 +123,24 @@ func TestParseString (test *testing.T) {
 	}
 	test.Logf("changing first rune from %c to x", runes[0].run)
 	runes[0].run = 'x'
+	test.Logf("first rune is now %c", runes[0].run)
 	tokenRune := tokens[0].runes[0].run
 	if tokenRune != 'x' {
 		test.Fatalf (
 			"tokens does not reference the same memory as runes after changing runes: %c, %c",
 			runes[0].run, tokenRune)
 	}
+	runeIndex := 0
+	for tokenIndex, token := range tokens {
+		tokenRunePtr := &token.runes[0]
+		runePtr      := &runes[runeIndex]
+
+		if runePtr != tokenRunePtr {
+			test.Fatalf (
+				"tokens[%d] does not reference runes[%d]: %p, %p",
+				tokenIndex, runeIndex, tokenRunePtr, runePtr)
+		}
+		
+		runeIndex += len(token.runes)
+	}
 }