move calls to cstdlib::getenv to env::getEnv

Wrapped the cstdlib::getenv() call into env::getEnv
so that it can be tested by mocking the env namespace,
by just dropping in test_env.cpp which implements those
methods and tying them a singleton upon which we can set
expectations.

Note: regardless of the approach taken to mock this, wrapping
this method is a good fix.

Change-Id: I65d22da08fc3dd76e6860f728c54e6c847ed07de
Signed-off-by: Patrick Venture <venture@google.com>

4 files changed, 24 insertions, 14 deletions

diff --git a/env.cpp b/env.cpp
index 09dd985..6841987 100644
--- a/env.cpp
+++ b/env.cpp
@@ -22,23 +22,23 @@
 
 namespace env {
 
+std::string getEnv(const char* key)
+{
+    auto value = std::getenv(key);
+    return (value) ? std::string(value) : std::string();
+}
+
 std::string getEnv(
     const char* prefix, const SensorSet::key_type& sensor)
 {
     std::string key;
-    std::string value;
 
     key.assign(prefix);
     key.append(1, '_');
     key.append(sensor.first);
     key.append(sensor.second);
-    auto env = getenv(key.c_str());
-    if (env)
-    {
-        value.assign(env);
-    }
 
-    return value;
+    return getEnv(key.c_str());
 }
 
 std::string getEnv(
diff --git a/env.hpp b/env.hpp
index 50a9fdb..fa23888 100644
--- a/env.hpp
+++ b/env.hpp
@@ -8,6 +8,16 @@ namespace env {
 
 /** @brief Reads an environment variable
  *
+ *  Reads the environment for that key
+ *
+ *  @param[in] key - the key
+ *
+ *  @return string - the env var value
+ */
+std::string getEnv(const char* key);
+
+/** @brief Reads an environment variable
+ *
  *  Reads <prefix>_<sensor.first><sensor.second>
  *
  *  @param[in] prefix - the variable prefix
diff --git a/mainloop.cpp b/mainloop.cpp
index 99c8020..37c2316 100644
--- a/mainloop.cpp
+++ b/mainloop.cpp
@@ -287,8 +287,8 @@ void MainLoop::getObject(SensorSet::container_t::const_reference sensor)
 {
     // Get list of return codes for removing sensors on device
     std::string deviceRmRCs;
-    auto devRmRCs = getenv("REMOVERCS");
-    if (devRmRCs)
+    auto devRmRCs = env::getEnv("REMOVERCS");
+    if (!devRmRCs.empty())
     {
         deviceRmRCs.assign(devRmRCs);
     }
@@ -534,10 +534,10 @@ void MainLoop::init()
     }
 
     {
-        auto interval = getenv("INTERVAL");
-        if (interval)
+        auto interval = env::getEnv("INTERVAL");
+        if (!interval.empty())
         {
-            _interval = strtoull(interval, NULL, 10);
+            _interval = strtoull(interval.c_str(), NULL, 10);
         }
     }
 }
diff --git a/targets.hpp b/targets.hpp
index fe256a3..02bdd4f 100644
--- a/targets.hpp
+++ b/targets.hpp
@@ -103,8 +103,8 @@ std::shared_ptr<T> addTarget(const SensorSet::key_type& sensor,
     if (fs::exists(sysfsFullPath))
     {
         auto useTarget = true;
-        auto tmEnv = getenv("TARGET_MODE");
-        if (tmEnv)
+        auto tmEnv = env::getEnv("TARGET_MODE");
+        if (!tmEnv.empty())
         {
             std::string mode{tmEnv};
             std::transform(mode.begin(), mode.end(), mode.begin(), toupper);