Add tests for precomposed character normalization.

Author: scossu

test/data/precomp_samples-single_line.csv

@@ -1,4 +1,4 @@
-"inherited","abcd",9078,,
+"inherited","abcd",9078,"s2r",
 "inherited","TUVX","tuvx","r2s",
 "rot3","defg","abcd","s2r",
 "rot3","HIJK","KLMN","r2s",

test/data/script_samples/unittest.csv

@@ -69,12 +69,12 @@ def _trans(script, lang, t_dir, opts, rom, deltas):
             capitalize=opts.get("capitalize"), options=opts)
     try:
         assert trans == rom
-    except AssertionError as e:
+    except AssertionError:
         if deltas is not None:
             print("F", end="")
             deltas.append((lang, script, ndiff([trans], [rom])))
         else:
-            raise e
+            raise AssertionError(f"Result: {trans}\nExpected: {rom}")
     else:
         if deltas:
             print(".", end="")