add fakeit mocking header library for unit tests

src/Makefile.test.include

@@ -25,6 +25,7 @@ GENERATED_TEST_FILES = $(JSON_TEST_FILES:.json=.json.h) $(RAW_TEST_FILES:.raw=.r
 
 # test_unite binary #
 UNITE_TESTS =\
+  test/fakeit/fakeit.hpp \
   test/arith_uint256_tests.cpp \
   test/scriptnum10.h \
   test/addrman_tests.cpp \

src/test/fakeit/README.md

@@ -0,0 +1,48 @@
+FakeIt
+======
+
+Unit-e uses (FakeIt 2.0.5)[]https://github.com/eranpeer/FakeIt/releases/tag/2.0.5]
+for mocking interfaces in unit tests.
+
+FakeIt is a simple mocking framework for C++. It supports GCC, Clang and MS Visual C++.
+
+FakeIt is written in C++11 and can be used for testing both C++11 and C++ projects.
+
+```cpp
+struct SomeInterface {
+	virtual int foo(int) = 0;
+	virtual int bar(string) = 0;
+};
+```
+```cpp
+// Instantiate a mock object.
+Mock<SomeInterface> mock;
+
+// Setup mock behavior.
+When(Method(mock,foo)).Return(1); // Method mock.foo will return 1 once.
+
+// Fetch the mock instance.
+SomeInterface &i = mock.get();
+
+// Will print "1".
+cout << i.foo(0);
+
+
+```
+Verify method invocation
+```cpp
+Mock<SomeInterface> mock;
+
+When(Method(mock,foo)).Return(0);
+
+SomeInterface &i = mock.get();
+
+// Production code
+i.foo(1);
+
+// Verify method mock.foo was invoked.
+Verify(Method(mock,foo));
+
+// Verify method mock.foo was invoked with specific arguments.
+Verify(Method(mock,foo).Using(1));
+```