Disable progress bars for non-interactive sessions

src/diffenator2/shape.py

@@ -5,6 +5,7 @@
 from dataclasses import dataclass
 import uharfbuzz as hb
 import os
+import sys
 from diffenator2 import THRESHOLD
 from diffenator2.renderer import FONT_SIZE, PixelDiffer
 from diffenator2.template_elements import Word, WordDiff, Glyph, GlyphDiff
@@ -15,6 +16,11 @@
 import csv
 
 
+def _progress_bar(iterable, **kwargs):
+    kwargs.setdefault("disable", not getattr(sys.stderr, "isatty", lambda: False)())
+    return tqdm.tqdm(iterable, **kwargs)
+
+
 # Hashing strategies for elements of a Harfbuzz buffer
 
 
@@ -68,7 +74,7 @@ def test_font_glyphs(font_a, font_b, threshold=THRESHOLD, font_size=FONT_SIZE):
     skip_glyphs = missing_glyphs | new_glyphs
     modified_glyphs = []
     differ = PixelDiffer(font_a, font_b, font_size=font_size)
-    for g in tqdm.tqdm(same_glyphs):
+    for g in _progress_bar(same_glyphs):
         pc, diff_map = differ.diff(g)
         if pc > threshold:
             glyph = GlyphDiff(g, "%.2f" % pc, diff_map)
@@ -161,7 +167,7 @@ def test_words(
 
     differ = PixelDiffer(font_a, font_b, font_size=font_size)
     word_list = parse_wordlist(word_file)
-    for i, word in tqdm.tqdm(enumerate(word_list), total=len(word_list)):
+    for i, word in _progress_bar(enumerate(word_list), total=len(word_list)):
         differ.set_script(word.script)
         differ.set_lang(word.lang)
         differ.set_features(word.ot_features)

tests/test_shape.py

@@ -0,0 +1,38 @@
+from diffenator2 import shape
+
+
+class _Stderr:
+    def __init__(self, is_tty):
+        self._is_tty = is_tty
+
+    def isatty(self):
+        return self._is_tty
+
+
+def test_progress_bar_is_disabled_for_non_interactive_stderr(monkeypatch):
+    calls = {}
+
+    def fake_tqdm(iterable, **kwargs):
+        calls.update(kwargs)
+        return iterable
+
+    monkeypatch.setattr(shape.sys, "stderr", _Stderr(False))
+    monkeypatch.setattr(shape.tqdm, "tqdm", fake_tqdm)
+
+    assert list(shape._progress_bar([1, 2], total=2)) == [1, 2]
+    assert calls["disable"] is True
+    assert calls["total"] == 2
+
+
+def test_progress_bar_is_kept_for_interactive_stderr(monkeypatch):
+    calls = {}
+
+    def fake_tqdm(iterable, **kwargs):
+        calls.update(kwargs)
+        return iterable
+
+    monkeypatch.setattr(shape.sys, "stderr", _Stderr(True))
+    monkeypatch.setattr(shape.tqdm, "tqdm", fake_tqdm)
+
+    assert list(shape._progress_bar([1, 2])) == [1, 2]
+    assert calls["disable"] is False