diff --git a/.arduino-ci.yml b/.arduino-ci.yml
index 67bb624b..5430a367 100644
--- a/.arduino-ci.yml
+++ b/.arduino-ci.yml
@@ -1,4 +1,3 @@
-  
 unittest:
     platforms:
         - mega2560
@@ -9,6 +8,7 @@ unittest:
       - "LiquidCrystal"
       - "RTClib"
       - "Keypad"
+      - "SD"
 
 compile:
     platforms:
@@ -20,3 +20,4 @@ compile:
       - "LiquidCrystal"
       - "RTClib"
       - "Keypad"
+      - "SD"
diff --git a/src/Devices/SD_TC.cpp b/src/Devices/SD_TC.cpp
new file mode 100644
index 00000000..17eadf46
--- /dev/null
+++ b/src/Devices/SD_TC.cpp
@@ -0,0 +1,50 @@
+#include "Devices/SD_TC.h"
+
+//  class variables
+SDClass_TC* SDClass_TC::_instance = nullptr;
+
+//  class methods
+/**
+ * accessor for singleton
+ */
+SDClass_TC* SDClass_TC::instance() {
+  if (!_instance) {
+    _instance = new SDClass_TC();
+  }
+  return _instance;
+}
+
+//  instance methods
+/**
+ * print the root directory and all subdirectories
+ */
+void SDClass_TC::printRootDirectory() {
+  File root = open("/");
+  printDirectory(root, 0);
+}
+
+/**
+ * print a specified directory with an indent
+ */
+void SDClass_TC::printDirectory(File dir, int numTabs) {
+  while (true) {
+    File entry = dir.openNextFile();
+    if (!entry) {
+      // no more files
+      break;
+    }
+    for (uint8_t i = 0; i < numTabs; i++) {
+      Serial.print('\t');
+    }
+    Serial.print(entry.name());
+    if (entry.isDirectory()) {
+      Serial.println(F("/"));
+      printDirectory(entry, numTabs + 1);
+    } else {
+      // files have sizes, directories do not
+      Serial.print(F("\t\t"));
+      Serial.println(entry.size(), DEC);
+    }
+    entry.close();
+  }
+}
diff --git a/src/Devices/SD_TC.h b/src/Devices/SD_TC.h
new file mode 100644
index 00000000..585cd4d3
--- /dev/null
+++ b/src/Devices/SD_TC.h
@@ -0,0 +1,24 @@
+#pragma once
+
+#include <Arduino.h>
+#ifdef MOCK_PINS_COUNT
+#include <SD_CI.h>
+#else
+#include <SD.h>
+#endif
+
+class SDClass_TC : public SDClass {
+public:
+  // class methods
+  static SDClass_TC* instance();
+
+  // instance methods
+  void printRootDirectory();
+
+private:
+  // class variables
+  static SDClass_TC* _instance;
+
+  // instance methods
+  void printDirectory(File dir, int numTabs);
+};
diff --git a/src/TankControllerLib.cpp b/src/TankControllerLib.cpp
index a393e1f0..acc5cf7b 100644
--- a/src/TankControllerLib.cpp
+++ b/src/TankControllerLib.cpp
@@ -36,6 +36,7 @@ TankControllerLib::TankControllerLib() {
   lcd = LiquidCrystal_TC::instance();
   log = Serial_TC::instance();
   log->print(F("TankControllerLib::TankControllerLib() - version "), TANK_CONTROLLER_VERSION);
+  SDClass_TC::instance()->printRootDirectory();
 }
 
 /**
diff --git a/src/TankControllerLib.h b/src/TankControllerLib.h
index a8f0105b..a2bcfbd5 100644
--- a/src/TankControllerLib.h
+++ b/src/TankControllerLib.h
@@ -5,6 +5,7 @@
 #include "Devices/EthernetServer_TC.h"
 #include "Devices/Keypad_TC.h"
 #include "Devices/LiquidCrystal_TC.h"
+#include "Devices/SD_TC.h"
 #include "Devices/Serial_TC.h"
 
 const char TANK_CONTROLLER_VERSION[] = "0.3.0";
diff --git a/test/SD.cpp b/test/SD.cpp
new file mode 100644
index 00000000..8efa8971
--- /dev/null
+++ b/test/SD.cpp
@@ -0,0 +1,13 @@
+#include <Arduino.h>
+#include <ArduinoUnitTests.h>
+
+#include "TankControllerLib.h"
+
+unittest(test) {
+  TankControllerLib* tank = TankControllerLib::instance();
+  SDClass_TC* sd = SDClass_TC::instance();
+  assertTrue(tank != nullptr);
+  assertTrue(sd != nullptr);
+}
+
+unittest_main()