diff --git a/jedi/api/environment.py b/jedi/api/environment.py
index 77b0a4be..38c546b9 100644
--- a/jedi/api/environment.py
+++ b/jedi/api/environment.py
@@ -17,7 +17,7 @@ import parso
 
 _VersionInfo = namedtuple('VersionInfo', 'major minor micro')
 
-_SUPPORTED_PYTHONS = ['3.6', '3.5', '3.4', '3.3', '2.7']
+_SUPPORTED_PYTHONS = ['3.7', '3.6', '3.5', '3.4', '3.3', '2.7']
 _SAFE_PATHS = ['/usr/bin', '/usr/local/bin']
 _CURRENT_VERSION = '%s.%s' % (sys.version_info.major, sys.version_info.minor)
 
@@ -147,13 +147,18 @@ class InterpreterEnvironment(_BaseEnvironment):
 
 
 def _get_virtual_env_from_var():
+    """Get virtualenv environment from VIRTUAL_ENV environment variable.
+
+    It uses `safe=False` with ``create_environment``, because the environment
+    variable is considered to be safe / controlled by the user solely.
+    """
     var = os.environ.get('VIRTUAL_ENV')
     if var is not None:
         if var == sys.prefix:
             return SameEnvironment()
 
         try:
-            return create_environment(var)
+            return create_environment(var, safe=False)
         except InvalidPythonEnvironment:
             pass
 
@@ -318,10 +323,10 @@ def _get_executables_from_windows_registry(version):
 
     # TODO: support Python Anaconda.
     sub_keys = [
-      r'SOFTWARE\Python\PythonCore\{version}\InstallPath',
-      r'SOFTWARE\Wow6432Node\Python\PythonCore\{version}\InstallPath',
-      r'SOFTWARE\Python\PythonCore\{version}-32\InstallPath',
-      r'SOFTWARE\Wow6432Node\Python\PythonCore\{version}-32\InstallPath'
+        r'SOFTWARE\Python\PythonCore\{version}\InstallPath',
+        r'SOFTWARE\Wow6432Node\Python\PythonCore\{version}\InstallPath',
+        r'SOFTWARE\Python\PythonCore\{version}-32\InstallPath',
+        r'SOFTWARE\Wow6432Node\Python\PythonCore\{version}-32\InstallPath'
     ]
     for root_key in [winreg.HKEY_CURRENT_USER, winreg.HKEY_LOCAL_MACHINE]:
         for sub_key in sub_keys:
diff --git a/jedi/evaluate/context/iterable.py b/jedi/evaluate/context/iterable.py
index a12cef7c..b43ede8a 100644
--- a/jedi/evaluate/context/iterable.py
+++ b/jedi/evaluate/context/iterable.py
@@ -358,21 +358,39 @@ class SequenceLiteralContext(Sequence):
             return []  # Direct closing bracket, doesn't contain items.
 
         if array_node.type == 'testlist_comp':
-            return array_node.children[::2]
+            # filter out (for now) pep 448 single-star unpacking
+            return [value for value in array_node.children[::2]
+                    if value.type != "star_expr"]
         elif array_node.type == 'dictorsetmaker':
             kv = []
             iterator = iter(array_node.children)
             for key in iterator:
-                op = next(iterator, None)
-                if op is None or op == ',':
-                    kv.append(key)  # A set.
-                else:
-                    assert op == ':'  # A dict.
-                    kv.append((key, next(iterator)))
+                if key == "**":
+                    # dict with pep 448 double-star unpacking
+                    # for now ignoring the values imported by **
+                    next(iterator)
                     next(iterator, None)  # Possible comma.
+                else:
+                    op = next(iterator, None)
+                    if op is None or op == ',':
+                        if key.type == "star_expr":
+                            # pep 448 single-star unpacking
+                            # for now ignoring values imported by *
+                            pass
+                        else:
+                            kv.append(key)  # A set.
+                    else:
+                        assert op == ':'  # A dict.
+                        kv.append((key, next(iterator)))
+                        next(iterator, None)  # Possible comma.
             return kv
         else:
-            return [array_node]
+            if array_node.type == "star_expr":
+                # pep 448 single-star unpacking
+                # for now ignoring values imported by *
+                return []
+            else:
+                return [array_node]
 
     def exact_key_items(self):
         """
diff --git a/jedi/evaluate/syntax_tree.py b/jedi/evaluate/syntax_tree.py
index 9e5cec41..0a553729 100644
--- a/jedi/evaluate/syntax_tree.py
+++ b/jedi/evaluate/syntax_tree.py
@@ -264,7 +264,8 @@ def eval_atom(context, atom):
             array_node_c = array_node.children
         except AttributeError:
             array_node_c = []
-        if c[0] == '{' and (array_node == '}' or ':' in array_node_c):
+        if c[0] == '{' and (array_node == '}' or ':' in array_node_c or
+                            '**' in array_node_c):
             context = iterable.DictLiteralContext(context.evaluator, context, atom)
         else:
             context = iterable.SequenceLiteralContext(context.evaluator, context, atom)
diff --git a/setup.py b/setup.py
index ebcd4e55..d964d541 100755
--- a/setup.py
+++ b/setup.py
@@ -31,7 +31,15 @@ setup(name='jedi',
       packages=find_packages(exclude=['test', 'test.*']),
       python_requires='>=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*',
       install_requires=install_requires,
-      extras_require={'dev': ['docopt']},
+      extras_require={
+          'testing': [
+              'pytest>=2.3.5',
+              # docopt for sith doctests
+              'docopt',
+              # coloroma for colored debug output
+              'colorama',
+          ],
+      },
       package_data={'jedi': ['evaluate/compiled/fake/*.pym']},
       platforms=['any'],
       classifiers=[
diff --git a/test/completion/types.py b/test/completion/types.py
index 19621b29..f0c4c838 100644
--- a/test/completion/types.py
+++ b/test/completion/types.py
@@ -131,3 +131,46 @@ set_t2 = set()
 
 #? ['clear', 'copy']
 set_t2.c
+
+# -----------------
+# pep 448 unpacking generalizations
+# -----------------
+# python >= 3.5
+
+d = {'a': 3}
+
+#? dict()
+{**d}
+
+#? str()
+{**d, "b": "b"}["b"]
+
+# Should resolve to int() but jedi is not smart enough yet
+# Here to make sure it doesn't result in crash though
+#? 
+{**d}["a"]
+
+s = {1, 2, 3}
+
+#? set()
+{*s}
+
+#? set()
+{*s, 4, *s}
+
+s = {1, 2, 3}
+# Should resolve to int() but jedi is not smart enough yet
+# Here to make sure it doesn't result in crash though
+#? 
+{*s}.pop()
+
+#? int()
+{*s, 4}.pop()
+
+# Should resolve to int() but jedi is not smart enough yet
+# Here to make sure it doesn't result in crash though
+#? 
+[*s][0]
+
+#? int()
+[*s, 4][0]
diff --git a/test/conftest.py b/test/conftest.py
index 0a5598e3..7291600a 100644
--- a/test/conftest.py
+++ b/test/conftest.py
@@ -126,11 +126,12 @@ class StaticAnalysisCase(object):
         return "<%s: %s>" % (self.__class__.__name__, os.path.basename(self._path))
 
 
-@pytest.fixture()
-def venv_path(tmpdir, environment):
+@pytest.fixture(scope='session')
+def venv_path(tmpdir_factory, environment):
     if environment.version_info.major < 3:
         pytest.skip("python -m venv does not exist in Python 2")
 
+    tmpdir = tmpdir_factory.mktemp('venv_path')
     dirname = os.path.join(tmpdir.dirname, 'venv')
 
     # We cannot use the Python from tox because tox creates virtualenvs and
diff --git a/test/test_api/test_environment.py b/test/test_api/test_environment.py
index a11e4857..98230e57 100644
--- a/test/test_api/test_environment.py
+++ b/test/test_api/test_environment.py
@@ -110,3 +110,22 @@ def test_create_environment_venv_path(venv_path):
 def test_create_environment_executable():
     environment = create_environment(sys.executable)
     assert environment.executable == sys.executable
+
+
+def test_get_default_environment_from_env_does_not_use_safe(tmpdir, monkeypatch):
+    fake_python = os.path.join(str(tmpdir), 'fake_python')
+    with open(fake_python, 'w') as f:
+        f.write('')
+
+    def _get_subprocess(self):
+        if self._start_executable != fake_python:
+            raise RuntimeError('Should not get called!')
+        self.executable = fake_python
+        self.path = 'fake'
+
+    monkeypatch.setattr('jedi.api.environment.Environment._get_subprocess',
+                        _get_subprocess)
+
+    monkeypatch.setenv('VIRTUAL_ENV', fake_python)
+    env = get_default_environment()
+    assert env.path == 'fake'
diff --git a/tox.ini b/tox.ini
index f450b735..92d61f87 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,16 +1,10 @@
 [tox]
 envlist = py27, py34, py35, py36
 [testenv]
-deps =
-    pytest>=2.3.5
-    pytest-cache
-# docopt for sith doctests
-    docopt
-# coloroma for colored debug output
-    colorama
+extras = testing
 # Overwrite the parso version (only used sometimes).
-#    git+https://github.com/davidhalter/parso.git
-    -rrequirements.txt
+# deps =
+#     git+https://github.com/davidhalter/parso.git
 passenv = JEDI_TEST_ENVIRONMENT
 setenv =
 # https://github.com/tomchristie/django-rest-framework/issues/1957
@@ -24,34 +18,29 @@ setenv =
     env36: JEDI_TEST_ENVIRONMENT=36
     env37: JEDI_TEST_ENVIRONMENT=37
 commands =
-    py.test {posargs:jedi test}
+    pytest {posargs:jedi test}
 [testenv:py27]
 deps =
 # for testing the typing module
     typing
 # numpydoc for typing scipy stack
     numpydoc
-    {[testenv]deps}
 [testenv:py34]
 deps =
     typing
     numpydoc
-    {[testenv]deps}
 [testenv:py35]
 deps =
     numpydoc
-    {[testenv]deps}
 [testenv:py36]
 deps =
     numpydoc
-    {[testenv]deps}
 [testenv:cov]
 deps =
     coverage
     numpydoc
-    {[testenv]deps}
 commands =
-    coverage run --source jedi -m py.test
+    coverage run --source jedi -m pytest
     coverage report
 [testenv:sith]
 commands =