tests: print string instead of int for Lexer::Token

Add wrapper for Lexer::Token printing, to have string value reported
instead of numeric value, that gives "newline" instead of "8" in test
results.
Original line numbers are kept in error messages as they were before.

src/lexer_test.cc

@@ -19,6 +19,16 @@
 
 using namespace std;
 
+string tok(Lexer::Token t) {
+  const char *str = Lexer::TokenName(t);
+  if (!str)
+    return "TokenOutOfRange: " + to_string(t);
+  return str;
+}
+
+#define EXPECT_EQ_TOK(t1, t2) \
+  EXPECT_EQ(tok(t1), tok(t2))
+
 TEST(Lexer, ReadVarValue) {
   Lexer lexer("plain text $var $VaR ${x}\n");
   EvalString eval;
@@ -83,8 +93,7 @@ TEST(Lexer, CommentEOF) {
   // Verify we don't run off the end of the string when the EOF is
   // mid-comment.
   Lexer lexer("# foo");
-  Lexer::Token token = lexer.ReadToken();
-  EXPECT_EQ(Lexer::ERROR, token);
+  EXPECT_EQ_TOK(Lexer::ERROR, lexer.ReadToken());
 }
 
 TEST(Lexer, Tabs) {