Fix memory leak in test.

test/cctest/parsing/test-scanner.cc

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Tests v8::internal::Scanner. Note that presently most unit tests for the
 // Scanner are in cctest/test-parsing.cc, rather than here.
 
 #include "src/handles-inl.h"
 #include "src/parsing/scanner-character-streams.h"
 #include "src/parsing/scanner.h"
 #include "src/unicode-cache.h"
 #include "test/cctest/cctest.h"
 
 using namespace v8::internal;
 
 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 {

[vogelheim, 2016/11/23 18:08:42]

This (& below) is an awful lot of boilerplate, just so that I can ignore memory
management in the tests themselves. I hope this makes the tests more readable,
but... not sure. Let me know if you disagree, or have a better idea.

+  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
 
 // DCHECK_TOK checks token equality, but by checking for equality of the token
 // names. That should have the same result, but has much nicer error messaages.
 #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);
   }
 
   // For each position:
   // - Scan through file,
   // - set a bookmark once the position is reached,
   // - scan a bit more,
   // - reset to the bookmark, and
   // - 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++) {
       if (i == bookmark_pos) {
         bookmark.Set();
       }
       DCHECK_TOK(tokens[i], scanner->Next());
     }
 
     bookmark.Apply();
     for (size_t i = bookmark_pos; i < tokens.size(); i++) {
       DCHECK_TOK(tokens[i], scanner->Next());
     }
   }
 }
 
 TEST(AllThePushbacks) {
   const struct {
     const char* src;
     const Token::Value tokens[5];  // Large enough for any of the test cases.
   } test_cases[] = {
       {"<-x", {Token::LT, Token::SUB, Token::IDENTIFIER, Token::EOS}},
       {"<!x", {Token::LT, Token::NOT, Token::IDENTIFIER, Token::EOS}},
       {"<!-x",
        {Token::LT, Token::NOT, Token::SUB, Token::IDENTIFIER, Token::EOS}},
       {"<!-- 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());
     }
     DCHECK_TOK(Token::EOS, scanner->Next());
   }
 }