Add pytest coverage for CLI and rendering behavior

tests/test_pager.py

@@ -0,0 +1,167 @@
+"""Tests for pager integration."""
+
+from __future__ import annotations
+
+import signal
+import subprocess
+from unittest.mock import MagicMock, patch
+
+from rp.pager import MousePager, _mouse_capable_less
+
+
+class TestMouseCapableLess:
+    """Tests for _mouse_capable_less()."""
+
+    def test_returns_path_when_less_supports_mouse(self) -> None:
+        with patch("rp.pager.shutil.which", return_value="/usr/bin/less"):
+            mock_result = MagicMock()
+            mock_result.stdout = "less 551 (POSIX regular expressions)"
+            mock_result.stderr = ""
+
+            with patch("rp.pager.subprocess.run", return_value=mock_result):
+                assert _mouse_capable_less() == "/usr/bin/less"
+
+    def test_returns_none_when_less_not_found(self) -> None:
+        with patch("rp.pager.shutil.which", return_value=None):
+            assert _mouse_capable_less() is None
+
+    def test_returns_none_when_less_too_old(self) -> None:
+        with patch("rp.pager.shutil.which", return_value="/usr/bin/less"):
+            mock_result = MagicMock()
+            mock_result.stdout = "less 444"
+            mock_result.stderr = ""
+
+            with patch("rp.pager.subprocess.run", return_value=mock_result):
+                assert _mouse_capable_less() is None
+
+    def test_returns_path_when_version_is_in_stderr(self) -> None:
+        with patch("rp.pager.shutil.which", return_value="/usr/bin/less"):
+            mock_result = MagicMock()
+            mock_result.stdout = ""
+            mock_result.stderr = "less 600"
+
+            with patch("rp.pager.subprocess.run", return_value=mock_result):
+                assert _mouse_capable_less() == "/usr/bin/less"
+
+    def test_returns_none_on_timeout(self) -> None:
+        with patch("rp.pager.shutil.which", return_value="/usr/bin/less"):
+            with patch(
+                "rp.pager.subprocess.run",
+                side_effect=subprocess.TimeoutExpired(cmd="less", timeout=5),
+            ):
+                assert _mouse_capable_less() is None
+
+    def test_returns_none_on_os_error(self) -> None:
+        with patch("rp.pager.shutil.which", return_value="/usr/bin/less"):
+            with patch("rp.pager.subprocess.run", side_effect=OSError("nope")):
+                assert _mouse_capable_less() is None
+
+    def test_returns_none_when_version_not_parseable(self) -> None:
+        with patch("rp.pager.shutil.which", return_value="/usr/bin/less"):
+            mock_result = MagicMock()
+            mock_result.stdout = "some random output"
+            mock_result.stderr = ""
+
+            with patch("rp.pager.subprocess.run", return_value=mock_result):
+                assert _mouse_capable_less() is None
+
+    def test_boundary_version_543(self) -> None:
+        with patch("rp.pager.shutil.which", return_value="/usr/bin/less"):
+            mock_result = MagicMock()
+            mock_result.stdout = "less 543"
+            mock_result.stderr = ""
+
+            with patch("rp.pager.subprocess.run", return_value=mock_result):
+                assert _mouse_capable_less() == "/usr/bin/less"
+
+    def test_boundary_version_542(self) -> None:
+        with patch("rp.pager.shutil.which", return_value="/usr/bin/less"):
+            mock_result = MagicMock()
+            mock_result.stdout = "less 542"
+            mock_result.stderr = ""
+
+            with patch("rp.pager.subprocess.run", return_value=mock_result):
+                assert _mouse_capable_less() is None
+
+
+class TestMousePager:
+    """Tests for MousePager.show()."""
+
+    def test_falls_back_to_system_pager_when_no_less(self) -> None:
+        pager = MousePager()
+
+        with patch("rp.pager._mouse_capable_less", return_value=None):
+            with patch("rp.pager.SystemPager") as mock_system_pager:
+                mock_instance = MagicMock()
+                mock_system_pager.return_value = mock_instance
+
+                pager.show("content")
+
+                mock_instance.show.assert_called_once_with("content")
+
+    def test_uses_less_when_available(self) -> None:
+        pager = MousePager()
+        mock_result = MagicMock()
+        mock_result.returncode = 0
+
+        with patch("rp.pager._mouse_capable_less", return_value="/usr/bin/less"):
+            with patch("rp.pager.subprocess.run", return_value=mock_result) as mock_run:
+                pager.show("hello")
+
+                mock_run.assert_called_once_with(
+                    ["/usr/bin/less", "-R", "--mouse"],
+                    input="hello",
+                    text=True,
+                )
+
+    def test_sigint_does_not_trigger_fallback_for_negative_code(self) -> None:
+        pager = MousePager()
+        mock_result = MagicMock()
+        mock_result.returncode = -signal.SIGINT
+
+        with patch("rp.pager._mouse_capable_less", return_value="/usr/bin/less"):
+            with patch("rp.pager.subprocess.run", return_value=mock_result):
+                with patch("rp.pager.SystemPager") as mock_system_pager:
+                    pager.show("content")
+
+                    mock_system_pager.assert_not_called()
+
+    def test_sigint_does_not_trigger_fallback_for_128_plus_code(self) -> None:
+        pager = MousePager()
+        mock_result = MagicMock()
+        mock_result.returncode = 128 + signal.SIGINT
+
+        with patch("rp.pager._mouse_capable_less", return_value="/usr/bin/less"):
+            with patch("rp.pager.subprocess.run", return_value=mock_result):
+                with patch("rp.pager.SystemPager") as mock_system_pager:
+                    pager.show("content")
+
+                    mock_system_pager.assert_not_called()
+
+    def test_nonzero_exit_triggers_fallback(self) -> None:
+        pager = MousePager()
+        mock_result = MagicMock()
+        mock_result.returncode = 1
+
+        with patch("rp.pager._mouse_capable_less", return_value="/usr/bin/less"):
+            with patch("rp.pager.subprocess.run", return_value=mock_result):
+                with patch("rp.pager.SystemPager") as mock_system_pager:
+                    mock_instance = MagicMock()
+                    mock_system_pager.return_value = mock_instance
+
+                    pager.show("content")
+
+                    mock_instance.show.assert_called_once_with("content")
+
+    def test_oserror_triggers_fallback(self) -> None:
+        pager = MousePager()
+
+        with patch("rp.pager._mouse_capable_less", return_value="/usr/bin/less"):
+            with patch("rp.pager.subprocess.run", side_effect=OSError("fail")):
+                with patch("rp.pager.SystemPager") as mock_system_pager:
+                    mock_instance = MagicMock()
+                    mock_system_pager.return_value = mock_instance
+
+                    pager.show("content")
+
+                    mock_instance.show.assert_called_once_with("content")