Adjust prompt path when backspacing a path

qutebrowser/mainwindow/prompt.py

@@ -538,7 +538,7 @@ class FilenamePrompt(_BasePrompt):
         self._lineedit = LineEdit(self)
         if question.default:
             self._lineedit.setText(question.default)
-        self._lineedit.textChanged.connect(self._set_fileview_root)
+        self._lineedit.textEdited.connect(self._set_fileview_root)
         self._vbox.addWidget(self._lineedit)
 
         self.setFocusProxy(self._lineedit)
@@ -546,18 +546,25 @@ class FilenamePrompt(_BasePrompt):
         self.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Preferred)
 
     @pyqtSlot(str)
-    def _set_fileview_root(self, path):
+    def _set_fileview_root(self, path, *, tabbed=False):
         """Set the root path for the file display."""
         separators = os.sep
         if os.altsep is not None:
             separators += os.altsep
 
-        if path == '/' or (path and path[-1] not in separators):
+        if not path:
             return
-        path.rstrip(separators)
+
+        dirname = os.path.dirname(path)
 
         try:
-            if not os.path.isdir(path):
+            if path[-1] in separators and os.path.isdir(path):
+                # Input like /foo/bar/ -> show /foo/bar/ contents
+                path = path.rstrip(separators)
+            elif os.path.isdir(dirname) and not tabbed:
+                # Input like /foo/ba -> show /foo contents
+                path = dirname
+            else:
                 return
         except OSError:
             return
@@ -580,6 +587,7 @@ class FilenamePrompt(_BasePrompt):
         log.prompt.debug('Inserting path {}'.format(path))
         self._lineedit.setText(path)
         self._lineedit.setFocus()
+        self._set_fileview_root(path, tabbed=True)
         if clicked:
             # Avoid having a ..-subtree highlighted
             self._file_view.setCurrentIndex(QModelIndex())

tests/unit/mainwindow/test_prompt.py

@@ -20,6 +20,7 @@
 import os
 
 import pytest
+from PyQt5.QtCore import Qt
 
 from qutebrowser.mainwindow import prompt as promptmod
 from qutebrowser.utils import usertypes
@@ -34,6 +35,7 @@ class TestFileCompletion:
 
     @pytest.fixture
     def get_prompt(self, qtbot):
+        """Get a function to display a prompt with a path."""
         def _get_prompt_func(path):
             question = usertypes.Question()
             question.title = "test"
@@ -56,6 +58,7 @@ class TestFileCompletion:
     ])
     def test_simple_completion(self, tmpdir, get_prompt, steps, where,
                                subfolder):
+        """Simply trying to tab through items."""
         for directory in 'abc':
             (tmpdir / directory).ensure(dir=True)
 
@@ -65,3 +68,20 @@ class TestFileCompletion:
             prompt.item_focus(where)
 
         assert prompt._lineedit.text() == str(tmpdir / subfolder)
+
+    def test_backspacing_path(self, qtbot, tmpdir, get_prompt):
+        """When we start deleting a path we want to see the subdir."""
+        for directory in ['bar', 'foo']:
+            (tmpdir / directory).ensure(dir=True)
+
+        prompt = get_prompt(str(tmpdir / 'foo') + os.sep)
+
+        # Deleting /f[oo/]
+        with qtbot.wait_signal(prompt._file_model.directoryLoaded):
+            for _ in range(3):
+                qtbot.keyPress(prompt._lineedit, Qt.Key_Backspace)
+
+        # We should now show / again, so tabbing twice gives us .. -> bar
+        prompt.item_focus('next')
+        prompt.item_focus('next')
+        assert prompt._lineedit.text() == str(tmpdir / 'bar')