Add more tests for the argument parsing.

.github/ISSUE_TEMPLATE/bug_report.md

@@ -19,7 +19,7 @@ For example:
 3. Plot the resulting...
 4. See error by checking...
 
-**Expected behavior**
+**Expected behaviour**
 What you expected to happen (if it's not already obvious from the context).
 
 **Plots**

tdms/tests/unit/test_argument_parser.cpp

@@ -0,0 +1,115 @@
+/**
+ * @file test_argument_parser.cpp
+ * @brief Tests of the argument parsing and file I/O.
+ */
+#include "argument_parser.h"
+
+#include <algorithm>
+#include <stdexcept>
+#include <string>
+#include <vector>
+
+#include <catch2/catch_test_macros.hpp>
+
+using std::string;
+using std::vector;
+
+/**
+ * @brief Test that the argument parser recovers the input arguments provided.
+ */
+TEST_CASE("Test parsing help") {
+  const char *input_args[] = {"tdms", "-h"};
+  auto args = ArgumentNamespace(2, const_cast<char **>(input_args));
+  REQUIRE(args.have_flag("-h"));
+}
+
+/** Drop the first and last component of an std::vector (needs size > 2!!). */
+template<typename T>
+vector<T> drop_first_and_last(const vector<T> &v) {
+  return vector<T>(v.begin() + 1, v.end() - 1);
+}
+
+/** Convert a vector of std::strings to an array of chars */
+const char **vector_to_array(const vector<string> &vec) {
+  const char **arr = new const char *[vec.size()] {};
+  std::transform(vec.begin(), vec.end(), arr,
+                 [](const std::string &s) { return s.c_str(); });
+  return arr;
+}
+// TODO: check with Will that this doesn't shadow the implementation
+
+/**
+ * @brief Test that the argument parser returns the correct filenames.
+ */
+TEST_CASE("Test parsing two filenames") {
+
+  const vector<string> input_args = {"tdms", "input_file.mat",
+                                     "output_file.mat"};
+  auto args = ArgumentNamespace(
+          input_args.size(), const_cast<char **>(vector_to_array(input_args)));
+
+  SECTION("Inputs") {
+    vector<string> expected_filenames = drop_first_and_last(input_args);
+    vector<string> parsed_filenames = args.input_filenames();
+    REQUIRE(expected_filenames == parsed_filenames);
+  }
+  SECTION("Output") {
+    string parsed = args.output_filename();
+    string expected = input_args[input_args.size() - 1];
+    REQUIRE(expected == parsed);
+  }
+  SECTION("Grid") {
+    REQUIRE(!args.has_grid_filename());
+    REQUIRE_THROWS_AS(args.grid_filename(), std::runtime_error);
+  }
+}
+
+/**
+ * @brief Test that the argument parser returns the correct filenames.
+ */
+TEST_CASE("Test parsing three filenames") {
+  vector<string> input_args = {"tdms", "input_file.mat", "grid_file.mat",
+                               "output_file.mat"};
+  auto args = ArgumentNamespace(
+          input_args.size(), const_cast<char **>(vector_to_array(input_args)));
+
+  SECTION("Input") {
+    vector<string> expected_filenames = drop_first_and_last(input_args);
+    vector<string> parsed_filenames = args.input_filenames();
+    REQUIRE(expected_filenames == parsed_filenames);
+  }
+  SECTION("Output") {
+    string parsed = args.output_filename();
+    string expected = input_args[input_args.size() - 1];
+    REQUIRE(expected == parsed);
+  }
+  SECTION("Grid") {
+    string parsed = args.grid_filename();
+    string expected = input_args[input_args.size() - 2];
+    REQUIRE(args.has_grid_filename());
+    REQUIRE(expected == parsed);
+  }
+}
+
+/**
+ * @brief Test that the argument correctly errors with the wrong number of file
+ * names.
+ */
+TEST_CASE("Test wrong number of file names") {
+  SECTION("Zero") {
+    const char *input_args[] = {"tdms"};
+    auto args = ArgumentNamespace(1, const_cast<char **>(input_args));
+    REQUIRE(!args.have_correct_number_of_filenames());
+  }
+  SECTION("One") {
+    const char *input_args[] = {"tdms", "input_file.mat"};
+    auto args = ArgumentNamespace(2, const_cast<char **>(input_args));
+    REQUIRE(!args.have_correct_number_of_filenames());
+  }
+  SECTION("Four") {
+    const char *input_args[] = {"tdms", "input_file.mat", "grid_file.mat",
+                                "output_file.mat", "fourth_file.mat"};
+    auto args = ArgumentNamespace(5, const_cast<char **>(input_args));
+    REQUIRE(!args.have_correct_number_of_filenames());
+  }
+}