Make :jseval use a fixed path with relative paths

doc/changelog.asciidoc

@@ -85,6 +85,8 @@ Changed
   again to navigate through completion items when a text was entered.
 - `:debug-pyeval` now has a `--file` arguemnt so it takes a filename instead of
   a line of code.
+- `:jseval --file` now searches relative paths in a js/ subdir in qutebrowser's
+  data dir, e.g. `~/.local/share/qutebrowser/js`.
 
 Fixed
 ~~~~~

doc/help/commands.asciidoc

@@ -639,7 +639,10 @@ Evaluate a JavaScript string.
 * +'js-code'+: The string/file to evaluate.
 
 ==== optional arguments
-* +*-f*+, +*--file*+: Interpret js-code as a path to a file.
+* +*-f*+, +*--file*+: Interpret js-code as a path to a file. If the path is relative, the file is searched in a js/ subdir
+ in qutebrowser's data dir, e.g.
+ `~/.local/share/qutebrowser/js`.
+
 * +*-q*+, +*--quiet*+: Don't show resulting JS object.
 * +*-w*+, +*--world*+: Ignored on QtWebKit. On QtWebEngine, a world ID or name to run the snippet in.
 

qutebrowser/browser/commands.py

@@ -39,7 +39,7 @@ from qutebrowser.browser import (urlmarks, browsertab, inspector, navigate,
                                  webelem, downloads)
 from qutebrowser.keyinput import modeman
 from qutebrowser.utils import (message, usertypes, log, qtutils, urlutils,
-                               objreg, utils, debug)
+                               objreg, utils, debug, standarddir)
 from qutebrowser.utils.usertypes import KeyMode
 from qutebrowser.misc import editor, guiprocess
 from qutebrowser.completion.models import urlmodel, miscmodels
@@ -2029,6 +2029,9 @@ class CommandDispatcher:
         Args:
             js_code: The string/file to evaluate.
             file: Interpret js-code as a path to a file.
+                  If the path is relative, the file is searched in a js/ subdir
+                  in qutebrowser's data dir, e.g.
+                  `~/.local/share/qutebrowser/js`.
             quiet: Don't show resulting JS object.
             world: Ignored on QtWebKit. On QtWebEngine, a world ID or name to
                    run the snippet in.
@@ -2058,6 +2061,9 @@ class CommandDispatcher:
 
         if file:
             path = os.path.expanduser(js_code)
+            if not os.path.isabs(path):
+                path = os.path.join(standarddir.data(), 'js')
+
             try:
                 with open(path, 'r', encoding='utf-8') as f:
                     js_code = f.read()

tests/end2end/features/misc.feature

@@ -118,8 +118,8 @@ Feature: Various utility commands.
         And "No output or error" should be logged
 
     Scenario: :jseval --file using a file that doesn't exist as js-code
-        When I run :jseval --file nonexistentfile
-        Then the error "[Errno 2] No such file or directory: 'nonexistentfile'" should be shown
+        When I run :jseval --file /nonexistentfile
+        Then the error "[Errno 2] No such file or directory: '/nonexistentfile'" should be shown
         And "No output or error" should not be logged
 
     # :debug-webaction