gpython: Implement -i (interactive inspect after program run) + promised interactive-mode tests

/reviewed-by @jerome
/reviewed-on nexedi/pygolang!15

gpython/__init__.py

@@ -41,7 +41,7 @@ $GPYTHON_RUNTIME=threads.
 from __future__ import print_function, absolute_import
 
 
-_pyopt = "c:m:OVW:X:"
+_pyopt = "c:im:OVW:X:"
 _pyopt_long = ('version',)
 
 # pymain mimics `python ...`
@@ -93,6 +93,7 @@ def pymain(argv, init=None):
     warnoptions = []    # collected `-W arg`
     reexec_with = []    # reexecute underlying python with those options (e.g. -O, -S, ...)
     reexec_argv = []    # if reexecuting, reexecute with this application-level argv
+    inspect = False     # inspect interactively at the end
 
     igetopt = _IGetOpt(argv, _pyopt, _pyopt_long)
     for (opt, arg) in igetopt:
@@ -147,6 +148,10 @@ def pymain(argv, init=None):
         elif opt == '-W':
             warnoptions.append(arg)
 
+        # -i inspect interactively
+        elif opt == '-i':
+            inspect = True
+
         else:
             print("unknown option: '%s'" % opt, file=sys.stderr)
             sys.exit(2)
@@ -173,7 +178,8 @@ def pymain(argv, init=None):
             sys.argv = ['']  if len(argv) == 0  else  argv # e.g. ['-']
             sys.path.insert(0, '')  # cwd
 
-            if sys.stdin.isatty():
+            if sys.stdin.isatty() or inspect:
+                inspect = False # no console after console
                 def run(mmain):
                     mmain.__file__ = '<stdin>'
                     _interact(mmain)
@@ -259,11 +265,23 @@ def pymain(argv, init=None):
     sys.modules['__main__'] = mmain
 
     # execute -m/-c/file/interactive
-    run(mmain)
+    import traceback
+    try:
+        run(mmain)
+    except:
+        # print exception becore going to interactive inspect
+        if inspect:
+            traceback.print_exc()
+        else:
+            raise
+    finally:
+        # interactive inspect
+        if inspect:
+            _interact(mmain, banner='')
 
 
 # _interact runs interactive console in mmain namespace.
-def _interact(mmain):
+def _interact(mmain, banner=None):
     import code, sys
     from six.moves import input as raw_input
     # like code.interact() but with overridden console.raw_input _and_
@@ -287,7 +305,7 @@ def _interact(mmain):
         return raw_input('')
     console.raw_input = _
 
-    console.interact()
+    console.interact(banner=banner)
 
 
 # execfile was removed in py3

gpython/gpython_test.py

@@ -34,9 +34,10 @@ testprog = join(here, 'testprog')
 
 is_pypy    = (platform.python_implementation() == 'PyPy')
 is_cpython = (platform.python_implementation() == 'CPython')
+is_gpython = ('GPython' in sys.version)
 
 # @gpython_only is marker to run a test only under gpython
-gpython_only = pytest.mark.skipif('GPython' not in sys.version, reason="gpython-only test")
+gpython_only = pytest.mark.skipif(not is_gpython, reason="gpython-only test")
 
 # runtime is pytest fixture that yields all variants of should be supported gpython runtimes:
 # '' - not specified (gpython should autoselect)
@@ -188,6 +189,31 @@ def test_pymain():
     _ = pyout(['testdata/hello.py', 'abc', 'def'], cwd=here)
     assert _ == b"hello\nworld\n['testdata/hello.py', 'abc', 'def']\n"
 
+    # -i after stdin (also tests interactive mode as -i forces interactive even on non-tty)
+    d = {
+        b'hellopy': b(hellopy),
+        b'ps1':     b'' # cpython emits prompt to stderr
+    }
+    if is_pypy and not is_gpython:
+        d['ps1'] = b'>>>> ' # native pypy emits prompt to stdout and >>>> instead of >>>
+    _ = pyout(['-i'], stdin=b'import hello\n', cwd=testdata)
+    assert _ == b"%(ps1)shello\nworld\n['']\n%(ps1)s"           % d
+    _ = pyout(['-i', '-'], stdin=b'import hello\n', cwd=testdata)
+    assert _ == b"%(ps1)shello\nworld\n['-']\n%(ps1)s"          % d
+    _ = pyout(['-i', '-', 'zzz'], stdin=b'import hello\n', cwd=testdata)
+    assert _ == b"%(ps1)shello\nworld\n['-', 'zzz']\n%(ps1)s"   % d
+
+    # -i after -c
+    _ = pyout(['-i', '-c', 'import hello'], stdin=b'hello.tag', cwd=testdata)
+    assert _ == b"hello\nworld\n['-c']\n%(ps1)s'~~HELLO~~'\n%(ps1)s"    % d
+    # -i after -m
+    _ = pyout(['-i', '-m', 'hello'], stdin=b'world.tag', cwd=testdata)
+    assert _ == b"hello\nworld\n['%(hellopy)s']\n%(ps1)s'~~WORLD~~'\n%(ps1)s"  % d
+    # -i after file
+    _ = pyout(['-i', 'testdata/hello.py'], stdin=b'tag', cwd=here)
+    assert _ == b"hello\nworld\n['testdata/hello.py']\n%(ps1)s'~~HELLO~~'\n%(ps1)s" % d
+
+
     # -W <opt>
     _ = pyout(['-Werror', '-Whello', '-W', 'ignore::DeprecationWarning',
                'testprog/print_warnings_setup.py'], cwd=here)

gpython/testdata/hello.py

@@ -6,3 +6,6 @@ import world
 # sys.argv
 import sys
 print(sys.argv)
+
+# variable in module namespace
+tag = '~~HELLO~~'

gpython/testdata/world.py

 print('world')
+
+# variable in module namespace
+tag = '~~WORLD~~'