gh-155976: Update LINES and COLS from stdscr in curses set_term

Author: pranavchoudhary-tech

Lib/test/test_curses.py

@@ -3325,40 +3325,40 @@ def test_set_term(self):
         self.assertIs(curses.set_term(b), a)
 
     def test_set_term_refreshes_lines_cols_colors(self):
+        from test.support import os_helper
         s1 = self.make_pty()
         s2 = self.make_pty()
-        a = curses.newterm('xterm', s1, s1)
-        if hasattr(curses, 'start_color'):
-            try:
-                curses.start_color()
-            except curses.error:
-                pass
-        b = curses.newterm('xterm-256color', s2, s2)
-        if hasattr(curses, 'start_color'):
-            try:
-                curses.start_color()
-            except curses.error:
-                pass
+        
+        with os_helper.EnvironmentVarGuard() as env:
+            env['LINES'] = '25'
+            env['COLUMNS'] = '80'
+            a = curses.newterm('xterm', s1, s1)
+            if hasattr(curses, 'start_color'):
+                try:
+                    curses.start_color()
+                except curses.error:
+                    pass
+            
+            env['LINES'] = '30'
+            env['COLUMNS'] = '100'
+            b = curses.newterm('xterm-256color', s2, s2)
+            if hasattr(curses, 'start_color'):
+                try:
+                    curses.start_color()
+                except curses.error:
+                    pass
 
         curses.set_term(a)
-        lines_a, cols_a = curses.LINES, curses.COLS
-        colors_a = getattr(curses, 'COLORS', None)
-
-        curses.set_term(b)
-        lines_b, cols_b = curses.LINES, curses.COLS
-        colors_b = getattr(curses, 'COLORS', None)
-
-        self.assertEqual(curses.set_term(a), b)
-        self.assertEqual(curses.LINES, lines_a)
-        self.assertEqual(curses.COLS, cols_a)
-        if colors_a is not None:
-            self.assertEqual(curses.COLORS, colors_a)
+        self.assertEqual((curses.LINES, curses.COLS), a.stdscr.getmaxyx())
+        self.assertNotEqual((curses.LINES, curses.COLS), b.stdscr.getmaxyx())
+        if hasattr(curses, 'COLORS'):
+            self.assertEqual(curses.COLORS, 8)
 
         self.assertEqual(curses.set_term(b), a)
-        self.assertEqual(curses.LINES, lines_b)
-        self.assertEqual(curses.COLS, cols_b)
-        if colors_b is not None:
-            self.assertEqual(curses.COLORS, colors_b)
+        self.assertEqual((curses.LINES, curses.COLS), b.stdscr.getmaxyx())
+        self.assertNotEqual((curses.LINES, curses.COLS), a.stdscr.getmaxyx())
+        if hasattr(curses, 'COLORS'):
+            self.assertEqual(curses.COLORS, 256)
 
     def test_window_keeps_screen_alive(self):
         # The standard window keeps its screen alive; dropping every other

Modules/_cursesmodule.c

@@ -7890,7 +7890,11 @@ update_lines_cols(PyObject *private_module)
         goto error;
     }
 
-    o = PyLong_FromLong(LINES);
+    int lines = LINES;
+    if (stdscr != NULL) {
+        lines = getmaxy(stdscr);
+    }
+    o = PyLong_FromLong(lines);
     if (o == NULL) {
         goto error;
     }
@@ -7902,7 +7906,11 @@ update_lines_cols(PyObject *private_module)
     }
     Py_DECREF(o);
 
-    o = PyLong_FromLong(COLS);
+    int cols = COLS;
+    if (stdscr != NULL) {
+        cols = getmaxx(stdscr);
+    }
+    o = PyLong_FromLong(cols);
     if (o == NULL) {
         goto error;
     }