feat: add APK download progress bar

tests/test_sideload.py

@@ -393,8 +393,10 @@ class TestFdroidSource:
             download_url="https://example.com/x.apk",
             expected_sha256=sha,
         )
-        result = source.download_apk(release, cache)
+        progress = mock.Mock()
+        result = source.download_apk(release, cache, progress=progress)
         assert result == cache.cached_path(app_entry.app_id, sha)
+        progress.assert_not_called()
 
     def test_download_apk_sha256_mismatch(self, app_entry: sideload.AppEntry, cache: sideload.DownloadCache):
         apk_data = b"real-content"
@@ -1293,6 +1295,52 @@ class TestUtilities:
         assert dest.read_bytes() == data
         assert not dest.with_suffix(".apk.tmp").exists()
 
+    def test_atomic_download_reports_content_length_progress(self, tmp_path: Path):
+        data = b"downloaded-content"
+        response = _mock_urlopen_response(data)
+        response.headers = {"Content-Length": str(len(data))}
+        updates = []
+        with _mock_download_opener(response):
+            result = sideload._atomic_download(
+                "https://example.com/x.apk",
+                tmp_path / "test.apk",
+                progress=lambda downloaded, total: updates.append((downloaded, total)),
+            )
+        assert result.read_bytes() == data
+        assert updates[0] == (0, len(data))
+        assert updates[-1] == (len(data), len(data))
+
+    def test_atomic_download_reports_indeterminate_progress(self, tmp_path: Path):
+        data = b"downloaded-content"
+        response = _mock_urlopen_response(data)
+        response.headers = {}
+        updates = []
+        with _mock_download_opener(response):
+            result = sideload._atomic_download(
+                "https://example.com/x.apk",
+                tmp_path / "test.apk",
+                expected_size=None,
+                progress=lambda downloaded, total: updates.append((downloaded, total)),
+            )
+        assert result.read_bytes() == data
+        assert updates[0] == (0, None)
+        assert updates[-1] == (len(data), None)
+
+    def test_atomic_download_uses_expected_size_without_content_length(self, tmp_path: Path):
+        data = b"downloaded-content"
+        response = _mock_urlopen_response(data)
+        response.headers = {}
+        updates = []
+        with _mock_download_opener(response):
+            sideload._atomic_download(
+                "https://example.com/x.apk",
+                tmp_path / "test.apk",
+                expected_size=len(data),
+                progress=lambda downloaded, total: updates.append((downloaded, total)),
+            )
+        assert updates[0] == (0, len(data))
+        assert updates[-1] == (len(data), len(data))
+
     def test_atomic_download_cleans_up_on_error(self, tmp_path: Path):
         dest = tmp_path / "file.apk"
         with _mock_download_opener(error=RuntimeError("fail")):