Added tests of comment merging.

Tweaked comment merging to pass tests.

src/fediblockhole/__init__.py

@@ -290,6 +290,10 @@ def merge_comments(oldcomment:str, newcomment:str) -> str:
     if oldcomment == newcomment or newcomment in ['', None]:
         return oldcomment
 
+    # If old comment is empty, just return the new one
+    if oldcomment in ['', None]:
+        return newcomment
+
     # We want to skip duplicate fragments so we don't end up
     # re-concatenating the same strings every time there's an
     # update, causing the comment to grow without bound.

tests/test_merge_comments.py

@@ -0,0 +1,68 @@
+""" Test merging of comments
+"""
+import pytest
+
+from fediblockhole import merge_comments
+
+def test_merge_blank_comments():
+    
+    oldcomment = ''
+    newcomment = ''
+
+    merged_comment = merge_comments(oldcomment, newcomment)
+
+    assert merged_comment == ''
+
+def test_merge_None_comments():
+    
+    oldcomment = None
+    newcomment = None
+
+    merged_comment = merge_comments(oldcomment, newcomment)
+
+    assert merged_comment == ''
+
+def test_merge_oldstr_newNone():
+    
+    oldcomment = 'fred, bibble'
+    newcomment = None
+
+    merged_comment = merge_comments(oldcomment, newcomment)
+
+    assert merged_comment == 'fred, bibble'
+
+def test_merge_oldempty_newcomment():
+    
+    oldcomment = ''
+    newcomment = 'fred, bibble'
+
+    merged_comment = merge_comments(oldcomment, newcomment)
+
+    assert merged_comment == 'fred, bibble'
+
+def test_merge_oldNone_newcomment():
+    
+    oldcomment = None
+    newcomment = 'fred, bibble'
+
+    merged_comment = merge_comments(oldcomment, newcomment)
+
+    assert merged_comment == 'fred, bibble'
+
+def test_merge_two_different():
+    
+    oldcomment = 'happy, medium, spinning'
+    newcomment = 'fred, bibble'
+
+    merged_comment = merge_comments(oldcomment, newcomment)
+
+    assert merged_comment == 'happy, medium, spinning, fred, bibble'
+
+def test_merge_overlaps():
+    
+    oldcomment = 'happy, medium, spinning'
+    newcomment = 'fred, medium, bibble, spinning'
+
+    merged_comment = merge_comments(oldcomment, newcomment)
+
+    assert merged_comment == 'happy, medium, spinning, fred, bibble'