tests: new test to confirm correct printing of tesseract install advice

tests/test_validation.py

@@ -70,6 +70,17 @@ def test_old_tesseract_error():
             vd.check_options(*make_opts_pm(pdf_renderer='sandwich', language='eng'))
 
 
+def test_tesseract_not_installed(caplog):
+    with patch('ocrmypdf.subprocess.run') as not_found:
+        not_found.side_effect = FileNotFoundError('tesseract')
+        with pytest.raises(MissingDependencyError, match="Could not find program"):
+            vd.check_options(*make_opts_pm())
+            assert (
+                "'tesseract' could not be executed" in caplog.text
+            ), "Error message not printed"
+            assert 'install' in caplog.text, "Install advice not printed"
+        not_found.assert_called()
+
 
 def test_lossless_redo():
     with pytest.raises(BadArgsError):