[lab2] added unit test skeleton for edit_distance function

lab2/test_edit_distance.cc

@@ -0,0 +1,41 @@
+/* A sketch of unit tests for an edit_distance function.
+ *
+ * The function is assumed to be
+ *    int edit_distance(const std::string&, const std::string&);
+ * and it is assumed to be declared in edit_distance.h
+ */
+#include "edit_distance.h"
+
+#include <iostream>
+
+bool do_test(const std::string& x, const std::string& y, int expected)
+{
+    auto actual = edit_distance(x, y);
+    if (actual != expected) {
+        std::cout << "*** WRONG: distance(" << x << ", " << y << ") was "
+                  << actual << ", expected " << expected << '\n';
+        return true;
+    }
+    return false;
+}
+
+int main()
+{
+    int res = do_test("foobar", "foobar", 0);
+    res += do_test("x", "x", 0);
+    res += do_test("baz", "bar", 1);
+    res += do_test("separate", "seperate", 1);
+    res += do_test("separate", "seprate", 1);
+    res += do_test("separate", "sepeate", 2);
+    res += do_test("separate", "desperate", 3);
+    res += do_test("separate", "federate", 3);
+    res += do_test("separate", "generate", 3);
+    res += do_test("color", "colour", 1);
+    res += do_test("color", "colr", 1);
+    res += do_test("volor", "colour", 2);
+
+    if (!res)
+        std::cout << "\nPassed\n";
+    else
+        std::cout << "\nFailed " << res << " tests\n";
+}