Added tests for char tools

Test/String__Lower.cpp

@@ -0,0 +1,72 @@
+#include <StringTools.h>
+#include "Catch2.h"
+
+// Tests that lowering an empty string returns an empty string
+TEST_CASE(__FILE__"/EmptyString", "[Strings][Lower]")
+{
+    // Setup
+    const std::string in = "";
+
+    // Exercise
+    const std::string out = StringTools::Lower(in);
+
+    // Verify
+    REQUIRE(out == "");
+    return;
+}
+
+// Tests that lowering a string without any letters returns itself
+TEST_CASE(__FILE__"/Symbols", "[Strings][Lower]")
+{
+    // Setup
+    const std::string in = "66! _-\n*";
+
+    // Exercise
+    const std::string out = StringTools::Lower(in);
+
+    // Verify
+    REQUIRE(out == "66! _-\n*");
+    return;
+}
+
+// Tests that lowering a string of lowercase letters returns itself
+TEST_CASE(__FILE__"/AlreadyLowered", "[Strings][Lower]")
+{
+    // Setup
+    const std::string in = "ughareyouserious";
+
+    // Exercise
+    const std::string out = StringTools::Lower(in);
+
+    // Verify
+    REQUIRE(out == "ughareyouserious");
+    return;
+}
+
+// Tests that lowering a string of uppercase letters returns the lowercase version
+TEST_CASE(__FILE__"/Uppercase", "[Strings][Lower]")
+{
+    // Setup
+    const std::string in = "UGHAREYOUSERIOUS";
+
+    // Exercise
+    const std::string out = StringTools::Lower(in);
+
+    // Verify
+    REQUIRE(out == "ughareyouserious");
+    return;
+}
+
+// Tests that lowering a string of uppercase, lowercase letters and symbols returns the lowercase version
+TEST_CASE(__FILE__"/Mixed", "[Strings][Lower]")
+{
+    // Setup
+    const std::string in = "Ugh, Are You Serious?! DON'T DO THAT!!!";
+
+    // Exercise
+    const std::string out = StringTools::Lower(in);
+
+    // Verify
+    REQUIRE(out == "ugh, are you serious?! don't do that!!!");
+    return;
+}