diff --git a/test/gpio.cpp b/test/gpio.cpp
new file mode 100644
index 0000000..cf01a0a
--- /dev/null
+++ b/test/gpio.cpp
@@ -0,0 +1,18 @@
+#include "gpio_mock.hpp"
+
+#include <memory>
+#include <string>
+
+// Set this before each test that hits a call to getEnv().
+GpioHandleInterface* gpioIntf;
+
+namespace gpio
+{
+
+std::unique_ptr<gpioplus::HandleInterface>
+    BuildGpioHandle(const std::string& gpiochip, const std::string& line)
+{
+    return (gpioIntf) ? gpioIntf->build(gpiochip, line) : nullptr;
+}
+
+} // namespace gpio
diff --git a/test/gpio_mock.hpp b/test/gpio_mock.hpp
new file mode 100644
index 0000000..d1acfef
--- /dev/null
+++ b/test/gpio_mock.hpp
@@ -0,0 +1,26 @@
+#pragma once
+
+#include <gpioplus/handle.hpp>
+#include <memory>
+#include <string>
+
+#include <gmock/gmock.h>
+
+class GpioHandleInterface
+{
+  public:
+    virtual ~GpioHandleInterface() = default;
+    virtual std::unique_ptr<gpioplus::HandleInterface>
+        build(const std::string& gpiochip, const std::string& line) const = 0;
+};
+
+class GpioHandleMock : public GpioHandleInterface
+{
+  public:
+    virtual ~GpioHandleMock() = default;
+    MOCK_CONST_METHOD2(build, std::unique_ptr<gpioplus::HandleInterface>(
+                                  const std::string&, const std::string&));
+};
+
+// Set this before each test that hits a call to getEnv().
+extern GpioHandleInterface* gpioIntf;