tests/test_general.py: test_2553(): cope with mupdf 1.23.4 and earlier.

mupdf-1.23.4 gives us orphaned surrogate characters, so we need to change
whether we expect 0xFFFD replacements depending on the mupdf version.

Also print out the various lists we are testing, useful for debugging.

tests/test_general.py

@@ -572,20 +572,43 @@ def test_2553():
     page = doc[0]
 
     # extract plain text, build set of all characters
-    set1 = set(page.get_text())
+    list1 = page.get_text()
+    set1 = set(list1)
 
     # extract text blocks, build set of all characters
-    set2 = set(page.get_text(sort=True))  # internally uses "blocks"
-
+    list2 = page.get_text(sort=True)  # internally uses "blocks"
+    set2 = set(list2)
+
     # extract textbox content, build set of all characters
-    set3 = set(page.get_textbox(page.rect))
-
+    list3 = page.get_textbox(page.rect)
+    set3 = set(list3)
+
+    def show(l):
+        ret = f'len={len(l)}\n'
+        for c in l:
+            cc = ord(c)
+            if (cc >= 32 and cc < 127) or c == '\n':
+                ret += c
+            else:
+                ret += f' [0x{hex(cc)}]'
+        return ret
+    print(f'list1:\n{show(list1)}')
+    print(f'list2:\n{show(list2)}')
+    print(f'list3:\n{show(list3)}')
+
     # all sets must be equal
     assert set1 == set2
     assert set1 == set3
 
-    # this special page contains no invalid Unicodes!
-    assert chr(0xFFFD) not in set1
+    # With mupdf later than 1.23.4, this special page contains no invalid
+    # Unicodes.
+    #
+    if fitz.mupdf_version_tuple > (1, 23, 4):
+        print(f'Checking no occurrence of 0xFFFD, {fitz.mupdf_version_tuple=}.')
+        assert chr(0xFFFD) not in set1
+    else:
+        print(f'Checking occurrence of 0xFFFD, {fitz.mupdf_version_tuple=}.')
+        assert chr(0xFFFD) in set1
 
 
 def test_2635():
@@ -596,4 +619,4 @@ def test_2635():
 
     page.clean_contents()  # clean page
     pix2 = page.get_pixmap()  # pixmap after cleaning
-    assert pix1.samples == pix2.samples  # assert equality
+    assert pix1.samples == pix2.samples  # assert equality