gn: Fix integer subtraction.

tools/gn/operators_unittest.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "tools/gn/operators.h"
 
 #include <stdint.h>
 #include <utility>
 
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 219 matching lines @@
   // The "var" variable should have been updated. Both instances of "foo" are
   // deleted.
   const Value* new_value = setup.scope()->GetValue(var);
   ASSERT_TRUE(new_value);
   ASSERT_EQ(Value::LIST, new_value->type());
   ASSERT_EQ(1u, new_value->list_value().size());
   ASSERT_EQ(Value::STRING, new_value->list_value()[0].type());
   EXPECT_EQ("bar", new_value->list_value()[0].string_value());
 }
 
+TEST(Operators, IntegerAdd) {
+  Err err;
+  TestWithScope setup;
+
+  TestBinaryOpNode node(Token::PLUS, "+");
+  node.SetLeftToValue(Value(nullptr, static_cast<int64_t>(123)));
+  node.SetRightToValue(Value(nullptr, static_cast<int64_t>(456)));
+  Value ret = ExecuteBinaryOperator(setup.scope(), &node, node.left(),
+                                    node.right(), &err);
+  ASSERT_FALSE(err.has_error());
+  ASSERT_EQ(Value::INTEGER, ret.type());
+  EXPECT_EQ(579, ret.int_value());
+}
+
+TEST(Operators, IntegerSubtract) {
+  Err err;
+  TestWithScope setup;
+
+  TestBinaryOpNode node(Token::MINUS, "-");
+  node.SetLeftToValue(Value(nullptr, static_cast<int64_t>(123)));
+  node.SetRightToValue(Value(nullptr, static_cast<int64_t>(456)));
+  Value ret = ExecuteBinaryOperator(setup.scope(), &node, node.left(),
+                                    node.right(), &err);
+  ASSERT_FALSE(err.has_error());
+  ASSERT_EQ(Value::INTEGER, ret.type());
+  EXPECT_EQ(-333, ret.int_value());
+}
+
 TEST(Operators, ShortCircuitAnd) {
   Err err;
   TestWithScope setup;
 
   // Set a && operator with the left to false.
   TestBinaryOpNode node(Token::BOOLEAN_AND, "&&");
   node.SetLeftToValue(Value(nullptr, false));
 
   // Set right as foo, but don't define a value for it.
   const char foo[] = "foo";
@@ skipping 104 matching lines @@
   TestBinaryOpNode node(Token::PLUS_EQUALS, "+=");
   node.SetLeftToIdentifier(foo);
   node.SetRightToValue(Value(nullptr, static_cast<int64_t>(1)));
   node.Execute(&nested, &err);
   ASSERT_FALSE(err.has_error());
 
   // Outer foo should be used, inner foo should not be.
   EXPECT_FALSE(setup.scope()->IsSetButUnused(foo));
   EXPECT_TRUE(nested.IsSetButUnused(foo));
 }