TDD in action

Let's see how to develop an Reverse Polish Notation (RPN) calculator application that follows the TDD approach. RPN is also known as the postfix notation. The expectation from the RPN Calculator application is to accept a postfix math expression as an input and return the evaluated result as the output. 

Step by step, I would like to demonstrate how one can follow the TDD approach while developing an application. As the first step, I would like to explain the project directory structure, then we'll move forward. Let's create a folder named Ex2 with the following structure:

Figure 7.19

The googletest folder is the gtest test library that has the necessary gtest and gmock header files. Now libgtest.a is the Google test static library that we created in the previous exercise. We are going to use the make utility to build our project, hence I have placed a Makefile in the project home directory. The src directory will hold the production code, while the test directory will hold all...