Fix memory leak in cctest/parsing/test-scanner.

BUG=chromium:662388

Review-Url: https://codereview.chromium.org/2495533003
Cr-Commit-Position: refs/heads/master@{#41266}

test/cctest/parsing/test-scanner.cc

@@ -17,10 +17,29 @@ namespace {
 
 const char src_simple[] = "function foo() { var x = 2 * a() + b; }";
 
-std::unique_ptr<Scanner> make_scanner(const char* src, UnicodeCache* cache) {
-  std::unique_ptr<Scanner> scanner(new Scanner(cache));
-  scanner->Initialize(ScannerStream::ForTesting(src).release());
-  return scanner;
+struct ScannerTestHelper {
+  ScannerTestHelper() = default;
+  ScannerTestHelper(ScannerTestHelper&& other)
+      : unicode_cache(std::move(other.unicode_cache)),
+        stream(std::move(other.stream)),
+        scanner(std::move(other.scanner)) {}
+
+  std::unique_ptr<UnicodeCache> unicode_cache;
+  std::unique_ptr<Utf16CharacterStream> stream;
+  std::unique_ptr<Scanner> scanner;
+
+  Scanner* operator->() const { return scanner.get(); }
+  Scanner* get() const { return scanner.get(); }
+};
+
+ScannerTestHelper make_scanner(const char* src) {
+  ScannerTestHelper helper;
+  helper.unicode_cache = std::unique_ptr<UnicodeCache>(new UnicodeCache);
+  helper.stream = ScannerStream::ForTesting(src);
+  helper.scanner =
+      std::unique_ptr<Scanner>(new Scanner(helper.unicode_cache.get()));
+  helper.scanner->Initialize(helper.stream.get());
+  return helper;
 }
 
 }  // anonymous namespace
@@ -30,13 +49,11 @@ std::unique_ptr<Scanner> make_scanner(const char* src, UnicodeCache* cache) {
 #define DCHECK_TOK(a, b) DCHECK_EQ(Token::Name(a), Token::Name(b))
 
 TEST(Bookmarks) {
-  UnicodeCache unicode_cache;
-
   // Scan through the given source and record the tokens for use as reference
   // below.
   std::vector<Token::Value> tokens;
   {
-    auto scanner = make_scanner(src_simple, &unicode_cache);
+    auto scanner = make_scanner(src_simple);
     do {
       tokens.push_back(scanner->Next());
     } while (scanner->current_token() != Token::EOS);
@@ -50,7 +67,7 @@ TEST(Bookmarks) {
   // - scan until the end.
   // At each step, compare to the reference token sequence generated above.
   for (size_t bookmark_pos = 0; bookmark_pos < tokens.size(); bookmark_pos++) {
-    auto scanner = make_scanner(src_simple, &unicode_cache);
+    auto scanner = make_scanner(src_simple);
     Scanner::BookmarkScope bookmark(scanner.get());
 
     for (size_t i = 0; i < std::min(bookmark_pos + 10, tokens.size()); i++) {
@@ -79,9 +96,8 @@ TEST(AllThePushbacks) {
       {"<!-- xx -->\nx", {Token::IDENTIFIER, Token::EOS}},
   };
 
-  UnicodeCache unicode_cache;
   for (const auto& test_case : test_cases) {
-    auto scanner = make_scanner(test_case.src, &unicode_cache);
+    auto scanner = make_scanner(test_case.src);
     for (size_t i = 0; test_case.tokens[i] != Token::EOS; i++) {
       DCHECK_TOK(test_case.tokens[i], scanner->Next());
     }