test/cli_argument_parser: add a test for dealing with "empty" command lines

src/test/cli_argument_parser.cpp

@@ -152,6 +152,37 @@ int main(int argc, char* argv[]) {
     delete[] validTestParameterList;
     std::cout << "Passed valid input test." << std::endl;
 
+    // empty input (valid and invalid) #################################
+    std::vector<CLI::Flag> emptyTestFlags;
+
+    std::vector<CLI::UnpositionalArgument> emptyTestUnpositionalArguments;
+
+    std::vector<CLI::PositionalArgument> emptyTestPositionalArguments;
+
+    const char** emptyTestParameterList = new const char*[1];
+    // The command is always a part of a command line, even if it is empty
+    // otherwise. Therefore, I think it is reasonable to assume that it
+    // will always be available.
+    emptyTestParameterList[0] = "test";
+    int emptyTestParameterCount = 1;
+
+    // valid
+    CLI::ArgumentsParser validEmptyTestParameterParser = CLI::ArgumentsParser(emptyTestParameterCount, emptyTestParameterList, emptyTestFlags, emptyTestUnpositionalArguments, emptyTestPositionalArguments);
+    ASSERT(!validEmptyTestParameterParser.wrongUsage);
+    ASSERT(validEmptyTestParameterParser.programName == std::string("test"));
+
+    //invalid
+    emptyTestPositionalArguments.push_back(CLI::PositionalArgument("argument", "positional argument"));
+
+    CLI::ArgumentsParser invalidEmptyTestParameterParser = CLI::ArgumentsParser(emptyTestParameterCount, emptyTestParameterList, emptyTestFlags, emptyTestUnpositionalArguments, emptyTestPositionalArguments);
+    ASSERT(invalidEmptyTestParameterParser.wrongUsage);
+    ASSERT(invalidEmptyTestParameterParser.programName == std::string("test"));
+    ASSERT(invalidEmptyTestParameterParser.getPositionalArgument(0).isError);
+    ASSERT(invalidEmptyTestParameterParser.getPositionalArgument(0).errorCode == ErrorCodes::NOT_PRESENT);
+
+    delete[] emptyTestParameterList;
+    std::cout << "Passed empty input test." << std::endl;
+
     //TODO add tests for invalid input
     std::cerr << "TODO: invalid input tests" << std::endl;