added pytest, moved dependencies

tests/test_dpi_font.py

@@ -1,18 +1,34 @@
-from PyQt6 import QtGui
+import pytest
 from piker.ui._style import DpiAwareFont
 
 class MockScreen:
+    def __init__(self, pdpi, ldpi, name="MockScreen"):
+        self._pdpi = pdpi
+        self._ldpi = ldpi
+        self._name = name
+
     def physicalDotsPerInch(self):
-        return 169  # example HiDPI
+        return self._pdpi
+
     def logicalDotsPerInch(self):
-        return 96
+        return self._ldpi
+
     def name(self):
-        return "MockScreen"
+        return self._name
 
-# create font instance
+@pytest.mark.parametrize(
+    "pdpi, ldpi",
+    [
+        (96, 96),       # normal DPI
+        (169, 96),      # HiDPI
+        (120, 96),      # mid-DPI
+    ]
+)
+def test_font_px_size(pdpi, ldpi):
     font = DpiAwareFont()
+    font.configure_to_dpi(screen=MockScreen(pdpi, ldpi))
 
-# pass the mock screen to configure_to_dpi
-font.configure_to_dpi(screen=MockScreen())
+    px = font.px_size
+    print(f"{pdpi}x{ldpi} DPI -> Computed pixel size: {px}")
 
-print("Computed pixel size:", font.px_size)
+    assert 12 <= px <= 24