base: Add UnSetEnv function to EnvVarGetter API.

base/env_var_unittest.cc

 // Copyright (c) 2010 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 "base/env_var.h"
 #include "base/scoped_ptr.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/platform_test.h"
 
 typedef PlatformTest EnvVarTest;
 
 TEST_F(EnvVarTest, GetEnvVar) {
   // Every setup should have non-empty PATH...
   scoped_ptr<base::EnvVarGetter> env(base::EnvVarGetter::Create());
   std::string env_value;
   EXPECT_TRUE(env->GetEnv("PATH", &env_value));
   EXPECT_NE(env_value, "");
 }
 
 TEST_F(EnvVarTest, HasEnvVar) {
   // Every setup should have PATH...
   scoped_ptr<base::EnvVarGetter> env(base::EnvVarGetter::Create());
   EXPECT_TRUE(env->HasEnv("PATH"));
 }
 
 TEST_F(EnvVarTest, SetEnvVar) {
+  scoped_ptr<base::EnvVarGetter> env(base::EnvVarGetter::Create());
+
   const char kFooUpper[] = "FOO";
   const char kFooLower[] = "foo";
-  scoped_ptr<base::EnvVarGetter> env(base::EnvVarGetter::Create());
   EXPECT_TRUE(env->SetEnv(kFooUpper, kFooLower));
 
   // Now verify that the environment has the new variable.
   EXPECT_TRUE(env->HasEnv(kFooUpper));
 
   std::string var_value;
   EXPECT_TRUE(env->GetEnv(kFooUpper, &var_value));
   EXPECT_EQ(var_value, kFooLower);
 }
+
+TEST_F(EnvVarTest, UnSetEnvVar) {
+  scoped_ptr<base::EnvVarGetter> env(base::EnvVarGetter::Create());
+
+  const char kFooUpper[] = "FOO";
+  const char kFooLower[] = "foo";
+  // First set some environment variable.
+  EXPECT_TRUE(env->SetEnv(kFooUpper, kFooLower));
+
+  // Now verify that the environment has the new variable.
+  EXPECT_TRUE(env->HasEnv(kFooUpper));
+
+  // Finally verify that the environment variable was erased.
+  EXPECT_TRUE(env->UnSetEnv(kFooUpper));
+
+  // And check that the variable has been unset.
+  EXPECT_FALSE(env->HasEnv(kFooUpper));
+}