BUG: GH29595 fix read_json() to use utf-8 for a default encoding (pandas-dev#29566)

Author: ryanking13

doc/source/whatsnew/v1.0.0.rst

@@ -400,6 +400,8 @@ I/O
 - Bug in :meth:`DataFrame.to_html` when using ``formatters=<list>`` and ``max_cols`` together. (:issue:`25955`)
 - Bug in :meth:`Styler.background_gradient` not able to work with dtype ``Int64`` (:issue:`28869`)
 - Bug in :meth:`DataFrame.to_clipboard` which did not work reliably in ipython (:issue:`22707`)
+- Bug in :func:`read_json` where default encoding was not set to ``utf-8`` (:issue:`29565`)
+-
 
 Plotting
 ^^^^^^^^

pandas/io/json/_json.py

@@ -577,6 +577,8 @@ def read_json(
         dtype = True
     if convert_axes is None and orient != "table":
         convert_axes = True
+    if encoding is None:
+        encoding = "utf-8"
 
     compression = _infer_compression(path_or_buf, compression)
     filepath_or_buffer, _, compression, should_close = get_filepath_or_buffer(

pandas/tests/io/json/test_readlines.py

@@ -173,3 +173,14 @@ def test_readjson_chunks_multiple_empty_lines(chunksize):
     tm.assert_frame_equal(
         orig, test, obj="chunksize: {chunksize}".format(chunksize=chunksize)
     )
+
+
+def test_readjson_unicode(monkeypatch):
+    with tm.ensure_clean("test.json") as path:
+        monkeypatch.setattr("_bootlocale.getpreferredencoding", lambda l: "cp949")
+        with open(path, "w", encoding="utf-8") as f:
+            f.write('{"£©µÀÆÖÞßéöÿ":["АБВГДабвгд가"]}')
+
+        result = read_json(path)
+        expected = pd.DataFrame({"£©µÀÆÖÞßéöÿ": ["АБВГДабвгд가"]})
+        tm.assert_frame_equal(result, expected)