there is a lot of code which is already for "WINDOWS", so try this:

chormeBinaryName = (OSName.contains("MAC")) ? "chromedriver" " "chromedriver.exe";

then reuse this code for both systems:

File chromeBinary = new File (
 +        "." + File.separator
 +        + "src" + File.separator
 +        + "test" + File.separator
 +        + "resources" + File.separator
 +        + "ChromeDriver" + File.separator
 +        + "ChromeDriver_OSX" + File.separator
 +        + chromeBinaryName
 +      );