Adding code coverage for unit tests executed on ArduinoCloudThing source (#18)

* Enable gathering of code coverage data upon execution of unit tests

* Extending README with information on how to build and execute the unit tests

* Adding badge for showing code coverage

Author: aentinger

.travis.yml

@@ -11,7 +11,13 @@ script:
   - cmake ..
   - make
 
-after_script:
+after_success:
+  - lcov --directory . --zerocounters
+  - bin/testArduinoCloudThing
+  - lcov --directory . --capture --output-file coverage.info
+  - lcov --remove coverage.info 'test/*' '/usr/*' 'lib/*' --output-file coverage.info
+  - lcov --list coverage.info
+  - bash <(curl -s https://codecov.io/bash) -f coverage.info
   - cd ..
   - rm -rf build
 

README.md

@@ -1,5 +1,6 @@
 # Arduino Cloud Thing Middleware
 [![Build Status](https://travis-ci.org/arduino-libraries/ArduinoCloudThing.svg?branch=master)](https://travis-ci.org/arduino-libraries/ArduinoCloudThing)
+[![Code Coverage](https://codecov.io/gh/arduino-libraries/ArduinoCloudThing/branch/master/graph/badge.svg)](https://codecov.io/gh/arduino-libraries/ArduinoCloudThing)
 
 This library contains the implementation of the class ArduinoCloudThing which allows to add **int**, **bool**, **float**, **String** properties which can be read from or written to the cloud. To achieve this goal ArduinoCloudThing possesses functions for encoding and decoding CBOR (Concise Binary Object Representation) encoded data which is used to transfer the properties value between a **thing** and the **cloud**.
 
@@ -53,3 +54,13 @@ thing.addProperty(int_property, "test_int_property", Permission::ReadWrite).publ
 * **decode** decodes a CBOR buffer received from the cloud and updates writeable properties accordingly. Also the update callbacks are called, if the value of a property has changed.
 
 `decode(uint8_t const * const data, size_t const length)`
+
+## Unit Tests
+
+The code of `ArduinoCloudThing` is verified via unit tests which are build and executed by the Travis CI system after every commit. However, one can also build and execute the unit tests manually using the following steps:
+```bash
+cd test && mkdir build && cd build
+cmake ..
+make -j4
+bin/testArduinoCloudThing
+```

test/CMakeLists.txt

@@ -53,15 +53,3 @@ add_executable(
 
 ##########################################################################
 
-add_custom_command(TARGET ${TEST_TARGET} POST_BUILD
-  COMMENT "Exeuting unit tests ..."
-  WORKING_DIRECTORY ${CMAKE_BINARY_DIR}
-  COMMAND lcov --directory . --zerocounters
-  COMMAND bin/${TEST_TARGET}
-  COMMAND lcov --directory . --capture --output-file coverage.info
-  COMMAND lcov --remove coverage.info 'test/*' '/usr/*' 'lib/*' --output-file coverage.info
-  COMMAND lcov --list coverage.info
-)
-
-##########################################################################
-