added new unit test cases.

Author: jacobwilliams

src/tests/jf_test_2.f90

@@ -138,6 +138,17 @@ subroutine test_2(error_cnt)
         call json%print_error_message(error_unit)
         error_cnt = error_cnt + 1
     end if
+    call json%add(inp, 'special chars', '\ /')
+    if (json%failed()) then
+        call json%print_error_message(error_unit)
+        error_cnt = error_cnt + 1
+    end if
+    call json%add(inp, 'special chars in key \ /', '\ /')
+    if (json%failed()) then
+        call json%print_error_message(error_unit)
+        error_cnt = error_cnt + 1
+    end if
+
     nullify(inp)
 
     !trajectory variables: