Attempted to fix issue with running tests on Windows.

tests/CMakeLists.txt

@@ -20,6 +20,14 @@ foreach(TEST ${TESTS})
     target_link_libraries(${TEST} QHttpEngine common)
     add_test(NAME ${TEST}
         COMMAND ${TEST}
-        WORKING_DIRECTORY "$<TARGET_FILE_DIR:QHttpEngine>"
     )
 endforeach()
+
+# On Windows, the library's DLL must exist in the same directory as the test
+# executables which link against it - create a custom command to copy it
+if(WIN32 NOT BUILD_STATIC)
+    add_custom_target(QHttpEngine-copy ALL
+        "${CMAKE_COMMAND}" -E copy "$<TARGET_FILE:QHttpEngine>" "${CMAKE_CURRENT_BINARY_DIR}"
+        DEPENDS QHttpEngine
+    )
+endif()