show_progress: add finished=true/false to archive_progress json, fixes #6570

also:
- remove empty values from final json
- add test

src/borg/archive.py

@@ -143,11 +143,15 @@ class Statistics:
         if dt is None or now - self.last_progress > dt:
             self.last_progress = now
             if self.output_json:
-                data = self.as_dict()
+                if not final:
+                    data = self.as_dict()
+                    data['path'] = remove_surrogates(item.path if item else '')
+                else:
+                    data = {}
                 data.update({
                     'time': time.time(),
                     'type': 'archive_progress',
-                    'path': remove_surrogates(item.path if item else ''),
+                    'finished': final,
                 })
                 msg = json.dumps(data)
                 end = '\n'

src/borg/testsuite/archive.py

@@ -1,3 +1,4 @@
+import json
 from collections import OrderedDict
 from datetime import datetime, timezone
 from io import StringIO
@@ -61,6 +62,34 @@ This archive:                   20 B                 10 B                 10 B""
     assert repr(stats) == f'<Statistics object at {id(stats):#x} (20, 10, 10)>'
 
 
+def test_stats_progress_json(stats):
+    stats.output_json = True
+
+    out = StringIO()
+    stats.show_progress(item=Item(path='foo'), stream=out)
+    result = json.loads(out.getvalue())
+    assert result['type'] == 'archive_progress'
+    assert isinstance(result['time'], float)
+    assert result['finished'] is False
+    assert result['path'] == 'foo'
+    assert result['original_size'] == 20
+    assert result['compressed_size'] == 10
+    assert result['deduplicated_size'] == 10
+    assert result['nfiles'] == 0  # this counter gets updated elsewhere
+
+    out = StringIO()
+    stats.show_progress(stream=out, final=True)
+    result = json.loads(out.getvalue())
+    assert result['type'] == 'archive_progress'
+    assert isinstance(result['time'], float)
+    assert result['finished'] is True  # see #6570
+    assert 'path' not in result
+    assert 'original_size' not in result
+    assert 'compressed_size' not in result
+    assert 'deduplicated_size' not in result
+    assert 'nfiles' not in result
+
+
 class MockCache:
 
     class MockRepo: