diff --git a/src/pip/_internal/cli/base_command.py b/src/pip/_internal/cli/base_command.py
index 6e1fd5b1a..549864936 100644
--- a/src/pip/_internal/cli/base_command.py
+++ b/src/pip/_internal/cli/base_command.py
@@ -22,9 +22,10 @@ from pip._internal.exceptions import (
 )
 from pip._internal.index import PackageFinder
 from pip._internal.locations import running_under_virtualenv
-from pip._internal.req.constructors import install_req_from_editable
+from pip._internal.req.constructors import (
+    install_req_from_editable, install_req_from_line,
+)
 from pip._internal.req.req_file import parse_requirements
-from pip._internal.req.req_install import InstallRequirement
 from pip._internal.utils.logging import setup_logging
 from pip._internal.utils.misc import get_prog, normalize_path
 from pip._internal.utils.outdated import pip_version_check
@@ -209,7 +210,7 @@ class RequirementCommand(Command):
                 requirement_set.add_requirement(req_to_add)
 
         for req in args:
-            req_to_add = InstallRequirement.from_line(
+            req_to_add = install_req_from_line(
                 req, None, isolated=options.isolated_mode,
                 wheel_cache=wheel_cache
             )
diff --git a/src/pip/_internal/commands/uninstall.py b/src/pip/_internal/commands/uninstall.py
index a62bf3674..0cd6f54bd 100644
--- a/src/pip/_internal/commands/uninstall.py
+++ b/src/pip/_internal/commands/uninstall.py
@@ -4,7 +4,8 @@ from pip._vendor.packaging.utils import canonicalize_name
 
 from pip._internal.cli.base_command import Command
 from pip._internal.exceptions import InstallationError
-from pip._internal.req import InstallRequirement, parse_requirements
+from pip._internal.req import parse_requirements
+from pip._internal.req.constructors import install_req_from_line
 from pip._internal.utils.misc import protect_pip_from_modification_on_windows
 
 
@@ -47,7 +48,7 @@ class UninstallCommand(Command):
         with self._build_session(options) as session:
             reqs_to_uninstall = {}
             for name in args:
-                req = InstallRequirement.from_line(
+                req = install_req_from_line(
                     name, isolated=options.isolated_mode,
                 )
                 if req.name:
diff --git a/src/pip/_internal/operations/freeze.py b/src/pip/_internal/operations/freeze.py
index 8ae8afe5d..1ceb7fedb 100644
--- a/src/pip/_internal/operations/freeze.py
+++ b/src/pip/_internal/operations/freeze.py
@@ -10,8 +10,9 @@ from pip._vendor.packaging.utils import canonicalize_name
 from pip._vendor.pkg_resources import RequirementParseError
 
 from pip._internal.exceptions import InstallationError
-from pip._internal.req import InstallRequirement
-from pip._internal.req.constructors import install_req_from_editable
+from pip._internal.req.constructors import (
+    install_req_from_editable, install_req_from_line,
+)
 from pip._internal.req.req_file import COMMENT_RE
 from pip._internal.utils.deprecation import deprecated
 from pip._internal.utils.misc import (
@@ -106,7 +107,7 @@ def freeze(
                             wheel_cache=wheel_cache,
                         )
                     else:
-                        line_req = InstallRequirement.from_line(
+                        line_req = install_req_from_line(
                             COMMENT_RE.sub('', line).strip(),
                             isolated=isolated,
                             wheel_cache=wheel_cache,
diff --git a/src/pip/_internal/req/constructors.py b/src/pip/_internal/req/constructors.py
index 770c66e37..b0e641bd7 100644
--- a/src/pip/_internal/req/constructors.py
+++ b/src/pip/_internal/req/constructors.py
@@ -8,18 +8,45 @@ These are meant to be used elsewhere within pip to create instances of
 InstallRequirement.
 """
 
+import logging
 import os
+import re
+import traceback
 
+from pip._vendor.packaging.markers import Marker
 from pip._vendor.packaging.requirements import InvalidRequirement, Requirement
+from pip._vendor.packaging.specifiers import Specifier
+from pip._vendor.pkg_resources import RequirementParseError, parse_requirements
 
-# XXX: Temporarily importing _strip_extras
-from pip._internal.download import path_to_url, url_to_path
+from pip._internal.download import (
+    is_archive_file, is_url, path_to_url, url_to_path,
+)
 from pip._internal.exceptions import InstallationError
 from pip._internal.models.link import Link
-from pip._internal.req.req_install import InstallRequirement, _strip_extras
+from pip._internal.req.req_install import InstallRequirement
+from pip._internal.utils.misc import is_installable_dir
 from pip._internal.vcs import vcs
+from pip._internal.wheel import Wheel
 
-__all__ = ["install_req_from_editable", "parse_editable"]
+__all__ = [
+    "install_req_from_editable", "install_req_from_line",
+    "parse_editable"
+]
+
+logger = logging.getLogger(__name__)
+operators = Specifier._operators.keys()
+
+
+def _strip_extras(path):
+    m = re.match(r'^(.+)(\[[^\]]+\])$', path)
+    extras = None
+    if m:
+        path_no_extras = m.group(1)
+        extras = m.group(2)
+    else:
+        path_no_extras = path
+
+    return path_no_extras, extras
 
 
 def parse_editable(editable_req):
@@ -87,6 +114,36 @@ def parse_editable(editable_req):
     return package_name, url, None
 
 
+def deduce_helpful_msg(req):
+    """Returns helpful msg in case requirements file does not exist,
+    or cannot be parsed.
+
+    :params req: Requirements file path
+    """
+    msg = ""
+    if os.path.exists(req):
+        msg = " It does exist."
+        # Try to parse and check if it is a requirements file.
+        try:
+            with open(req, 'r') as fp:
+                # parse first line only
+                next(parse_requirements(fp.read()))
+                msg += " The argument you provided " + \
+                    "(%s) appears to be a" % (req) + \
+                    " requirements file. If that is the" + \
+                    " case, use the '-r' flag to install" + \
+                    " the packages specified within it."
+        except RequirementParseError:
+            logger.debug("Cannot parse '%s' as requirements \
+            file" % (req), exc_info=1)
+    else:
+        msg += " File '%s' does not exist." % (req)
+    return msg
+
+
+# ---- The actual constructors follow ----
+
+
 def install_req_from_editable(
     editable_req, comes_from=None, isolated=False, options=None,
     wheel_cache=None, constraint=False
@@ -114,3 +171,102 @@ def install_req_from_editable(
         wheel_cache=wheel_cache,
         extras=extras_override or (),
     )
+
+
+def install_req_from_line(
+    name, comes_from=None, isolated=False, options=None, wheel_cache=None,
+    constraint=False
+):
+    """Creates an InstallRequirement from a name, which might be a
+    requirement, directory containing 'setup.py', filename, or URL.
+    """
+    if is_url(name):
+        marker_sep = '; '
+    else:
+        marker_sep = ';'
+    if marker_sep in name:
+        name, markers = name.split(marker_sep, 1)
+        markers = markers.strip()
+        if not markers:
+            markers = None
+        else:
+            markers = Marker(markers)
+    else:
+        markers = None
+    name = name.strip()
+    req = None
+    path = os.path.normpath(os.path.abspath(name))
+    link = None
+    extras = None
+
+    if is_url(name):
+        link = Link(name)
+    else:
+        p, extras = _strip_extras(path)
+        looks_like_dir = os.path.isdir(p) and (
+            os.path.sep in name or
+            (os.path.altsep is not None and os.path.altsep in name) or
+            name.startswith('.')
+        )
+        if looks_like_dir:
+            if not is_installable_dir(p):
+                raise InstallationError(
+                    "Directory %r is not installable. Neither 'setup.py' "
+                    "nor 'pyproject.toml' found." % name
+                )
+            link = Link(path_to_url(p))
+        elif is_archive_file(p):
+            if not os.path.isfile(p):
+                logger.warning(
+                    'Requirement %r looks like a filename, but the '
+                    'file does not exist',
+                    name
+                )
+            link = Link(path_to_url(p))
+
+    # it's a local file, dir, or url
+    if link:
+        # Handle relative file URLs
+        if link.scheme == 'file' and re.search(r'\.\./', link.url):
+            link = Link(
+                path_to_url(os.path.normpath(os.path.abspath(link.path))))
+        # wheel file
+        if link.is_wheel:
+            wheel = Wheel(link.filename)  # can raise InvalidWheelFilename
+            req = "%s==%s" % (wheel.name, wheel.version)
+        else:
+            # set the req to the egg fragment.  when it's not there, this
+            # will become an 'unnamed' requirement
+            req = link.egg_fragment
+
+    # a requirement specifier
+    else:
+        req = name
+
+    if extras:
+        extras = Requirement("placeholder" + extras.lower()).extras
+    else:
+        extras = ()
+    if req is not None:
+        try:
+            req = Requirement(req)
+        except InvalidRequirement:
+            if os.path.sep in req:
+                add_msg = "It looks like a path."
+                add_msg += deduce_helpful_msg(req)
+            elif '=' in req and not any(op in req for op in operators):
+                add_msg = "= is not a valid operator. Did you mean == ?"
+            else:
+                add_msg = traceback.format_exc()
+            raise InstallationError(
+                "Invalid requirement: '%s'\n%s" % (req, add_msg)
+            )
+
+    return InstallRequirement(
+        req, comes_from, link=link, markers=markers,
+        isolated=isolated,
+        options=options if options else {},
+        wheel_cache=wheel_cache,
+        constraint=constraint,
+        extras=extras,
+    )
diff --git a/src/pip/_internal/req/req_file.py b/src/pip/_internal/req/req_file.py
index 17bd372de..e7acf7cb8 100644
--- a/src/pip/_internal/req/req_file.py
+++ b/src/pip/_internal/req/req_file.py
@@ -16,8 +16,9 @@ from pip._vendor.six.moves.urllib import parse as urllib_parse
 from pip._internal.cli import cmdoptions
 from pip._internal.download import get_file_content
 from pip._internal.exceptions import RequirementsFileParseError
-from pip._internal.req.constructors import install_req_from_editable
-from pip._internal.req.req_install import InstallRequirement
+from pip._internal.req.constructors import (
+    install_req_from_editable, install_req_from_line,
+)
 
 __all__ = ['parse_requirements']
 
@@ -152,7 +153,7 @@ def process_line(line, filename, line_number, finder=None, comes_from=None,
         for dest in SUPPORTED_OPTIONS_REQ_DEST:
             if dest in opts.__dict__ and opts.__dict__[dest]:
                 req_options[dest] = opts.__dict__[dest]
-        yield InstallRequirement.from_line(
+        yield install_req_from_line(
             args_str, line_comes_from, constraint=constraint,
             isolated=isolated, options=req_options, wheel_cache=wheel_cache
         )
diff --git a/src/pip/_internal/req/req_install.py b/src/pip/_internal/req/req_install.py
index a2d8cc82e..c1989a50a 100644
--- a/src/pip/_internal/req/req_install.py
+++ b/src/pip/_internal/req/req_install.py
@@ -2,27 +2,21 @@ from __future__ import absolute_import
 
 import logging
 import os
-import re
 import shutil
 import sys
 import sysconfig
-import traceback
 import zipfile
 from distutils.util import change_root
 
 from pip._vendor import pkg_resources, six
-from pip._vendor.packaging import specifiers
-from pip._vendor.packaging.markers import Marker
 from pip._vendor.packaging.requirements import InvalidRequirement, Requirement
 from pip._vendor.packaging.utils import canonicalize_name
 from pip._vendor.packaging.version import Version
 from pip._vendor.packaging.version import parse as parse_version
 from pip._vendor.pep517.wrappers import Pep517HookCaller
-from pip._vendor.pkg_resources import RequirementParseError, parse_requirements
 
 from pip._internal import wheel
 from pip._internal.build_env import NoOpBuildEnvironment
-from pip._internal.download import is_archive_file, is_url, path_to_url
 from pip._internal.exceptions import InstallationError
 from pip._internal.locations import (
     PIP_DELETE_MARKER_FILENAME, running_under_virtualenv,
@@ -37,31 +31,17 @@ from pip._internal.utils.logging import indent_log
 from pip._internal.utils.misc import (
     _make_build_dir, ask_path_exists, backup_dir, call_subprocess,
     display_path, dist_in_site_packages, dist_in_usersite, ensure_dir,
-    get_installed_version, is_installable_dir, rmtree,
+    get_installed_version, rmtree,
 )
 from pip._internal.utils.packaging import get_metadata
 from pip._internal.utils.setuptools_build import SETUPTOOLS_SHIM
 from pip._internal.utils.temp_dir import TempDirectory
 from pip._internal.utils.ui import open_spinner
 from pip._internal.vcs import vcs
-from pip._internal.wheel import Wheel, move_wheel_files
+from pip._internal.wheel import move_wheel_files
 
 logger = logging.getLogger(__name__)
 
-operators = specifiers.Specifier._operators.keys()
-
-
-def _strip_extras(path):
-    m = re.match(r'^(.+)(\[[^\]]+\])$', path)
-    extras = None
-    if m:
-        path_no_extras = m.group(1)
-        extras = m.group(2)
-    else:
-        path_no_extras = path
-
-    return path_no_extras, extras
-
 
 class InstallRequirement(object):
     """
@@ -168,102 +148,6 @@ class InstallRequirement(object):
 
         return cls(req, comes_from, isolated=isolated, wheel_cache=wheel_cache)
 
-    @classmethod
-    def from_line(
-            cls, name, comes_from=None, isolated=False, options=None,
-            wheel_cache=None, constraint=False):
-        """Creates an InstallRequirement from a name, which might be a
-        requirement, directory containing 'setup.py', filename, or URL.
-        """
-        if is_url(name):
-            marker_sep = '; '
-        else:
-            marker_sep = ';'
-        if marker_sep in name:
-            name, markers = name.split(marker_sep, 1)
-            markers = markers.strip()
-            if not markers:
-                markers = None
-            else:
-                markers = Marker(markers)
-        else:
-            markers = None
-        name = name.strip()
-        req = None
-        path = os.path.normpath(os.path.abspath(name))
-        link = None
-        extras = None
-
-        if is_url(name):
-            link = Link(name)
-        else:
-            p, extras = _strip_extras(path)
-            looks_like_dir = os.path.isdir(p) and (
-                os.path.sep in name or
-                (os.path.altsep is not None and os.path.altsep in name) or
-                name.startswith('.')
-            )
-            if looks_like_dir:
-                if not is_installable_dir(p):
-                    raise InstallationError(
-                        "Directory %r is not installable. Neither 'setup.py' "
-                        "nor 'pyproject.toml' found." % name
-                    )
-                link = Link(path_to_url(p))
-            elif is_archive_file(p):
-                if not os.path.isfile(p):
-                    logger.warning(
-                        'Requirement %r looks like a filename, but the '
-                        'file does not exist',
-                        name
-                    )
-                link = Link(path_to_url(p))
-
-        # it's a local file, dir, or url
-        if link:
-            # Handle relative file URLs
-            if link.scheme == 'file' and re.search(r'\.\./', link.url):
-                link = Link(
-                    path_to_url(os.path.normpath(os.path.abspath(link.path))))
-            # wheel file
-            if link.is_wheel:
-                wheel = Wheel(link.filename)  # can raise InvalidWheelFilename
-                req = "%s==%s" % (wheel.name, wheel.version)
-            else:
-                # set the req to the egg fragment.  when it's not there, this
-                # will become an 'unnamed' requirement
-                req = link.egg_fragment
-
-        # a requirement specifier
-        else:
-            req = name
-
-        if extras:
-            extras = Requirement("placeholder" + extras.lower()).extras
-        else:
-            extras = ()
-        if req is not None:
-            try:
-                req = Requirement(req)
-            except InvalidRequirement:
-                if os.path.sep in req:
-                    add_msg = "It looks like a path."
-                    add_msg += deduce_helpful_msg(req)
-                elif '=' in req and not any(op in req for op in operators):
-                    add_msg = "= is not a valid operator. Did you mean == ?"
-                else:
-                    add_msg = traceback.format_exc()
-                raise InstallationError(
-                    "Invalid requirement: '%s'\n%s" % (req, add_msg))
-        return cls(
-            req, comes_from, link=link, markers=markers,
-            isolated=isolated,
-            options=options if options else {},
-            wheel_cache=wheel_cache,
-            constraint=constraint,
-            extras=extras,
-        )
-
     def __str__(self):
         if self.req:
             s = str(self.req)
@@ -998,30 +882,3 @@ class InstallRequirement(object):
                                           py_ver_str, self.name)]
 
         return install_args
-
-
-def deduce_helpful_msg(req):
-    """Returns helpful msg in case requirements file does not exist,
-    or cannot be parsed.
-
-    :params req: Requirements file path
-    """
-    msg = ""
-    if os.path.exists(req):
-        msg = " It does exist."
-        # Try to parse and check if it is a requirements file.
-        try:
-            with open(req, 'r') as fp:
-                # parse first line only
-                next(parse_requirements(fp.read()))
-                msg += " The argument you provided " + \
-                    "(%s) appears to be a" % (req) + \
-                    " requirements file. If that is the" + \
-                    " case, use the '-r' flag to install" + \
-                    " the packages specified within it."
-        except RequirementParseError:
-            logger.debug("Cannot parse '%s' as requirements \
-            file" % (req), exc_info=1)
-    else:
-        msg += " File '%s' does not exist." % (req)
-    return msg
diff --git a/tests/functional/test_uninstall.py b/tests/functional/test_uninstall.py
index c9ce8b8d3..7fd47b17e 100644
--- a/tests/functional/test_uninstall.py
+++ b/tests/functional/test_uninstall.py
@@ -11,7 +11,7 @@ from tempfile import mkdtemp
 import pretend
 import pytest
 
-from pip._internal.req import InstallRequirement
+from pip._internal.req.constructors import install_req_from_line
 from pip._internal.utils.misc import rmtree
 from tests.lib import assert_all_changes, create_test_package_with_setup
 from tests.lib.local_repos import local_checkout, local_repo
@@ -439,7 +439,7 @@ def test_uninstall_non_local_distutils(caplog, monkeypatch, tmpdir):
     get_dist = pretend.call_recorder(lambda x: dist)
     monkeypatch.setattr("pip._vendor.pkg_resources.get_distribution", get_dist)
 
-    req = InstallRequirement.from_line("thing")
+    req = install_req_from_line("thing")
     req.uninstall()
 
     assert os.path.exists(einfo)
diff --git a/tests/unit/test_finder.py b/tests/unit/test_finder.py
index 51fccfae1..969f81e2d 100644
--- a/tests/unit/test_finder.py
+++ b/tests/unit/test_finder.py
@@ -14,13 +14,13 @@ from pip._internal.exceptions import (
 from pip._internal.index import (
     FormatControl, InstallationCandidate, Link, PackageFinder, fmt_ctl_formats,
 )
-from pip._internal.req import InstallRequirement
+from pip._internal.req.constructors import install_req_from_line
 
 
 def test_no_mpkg(data):
     """Finder skips zipfiles with "macosx10" in the name."""
     finder = PackageFinder([data.find_links], [], session=PipSession())
-    req = InstallRequirement.from_line("pkgwithmpkg")
+    req = install_req_from_line("pkgwithmpkg")
     found = finder.find_requirement(req, False)
 
     assert found.url.endswith("pkgwithmpkg-1.0.tar.gz"), found
@@ -29,7 +29,7 @@ def test_no_mpkg(data):
 def test_no_partial_name_match(data):
     """Finder requires the full project name to match, not just beginning."""
     finder = PackageFinder([data.find_links], [], session=PipSession())
-    req = InstallRequirement.from_line("gmpy")
+    req = install_req_from_line("gmpy")
     found = finder.find_requirement(req, False)
 
     assert found.url.endswith("gmpy-1.15.tar.gz"), found
@@ -40,7 +40,7 @@ def test_tilde():
     session = PipSession()
     with patch('pip._internal.index.os.path.exists', return_value=True):
         finder = PackageFinder(['~/python-pkgs'], [], session=session)
-    req = InstallRequirement.from_line("gmpy")
+    req = install_req_from_line("gmpy")
     with pytest.raises(DistributionNotFound):
         finder.find_requirement(req, False)
 
@@ -53,7 +53,7 @@ def test_duplicates_sort_ok(data):
         [],
         session=PipSession(),
     )
-    req = InstallRequirement.from_line("duplicate")
+    req = install_req_from_line("duplicate")
     found = finder.find_requirement(req, False)
 
     assert found.url.endswith("duplicate-1.0.tar.gz"), found
@@ -61,7 +61,7 @@ def test_duplicates_sort_ok(data):
 
 def test_finder_detects_latest_find_links(data):
     """Test PackageFinder detects latest using find-links"""
-    req = InstallRequirement.from_line('simple', None)
+    req = install_req_from_line('simple', None)
     finder = PackageFinder([data.find_links], [], session=PipSession())
     link = finder.find_requirement(req, False)
     assert link.url.endswith("simple-3.0.tar.gz")
@@ -69,7 +69,7 @@ def test_finder_detects_latest_find_links(data):
 
 def test_incorrect_case_file_index(data):
     """Test PackageFinder detects latest using wrong case"""
-    req = InstallRequirement.from_line('dinner', None)
+    req = install_req_from_line('dinner', None)
     finder = PackageFinder([], [data.find_links3], session=PipSession())
     link = finder.find_requirement(req, False)
     assert link.url.endswith("Dinner-2.0.tar.gz")
@@ -78,7 +78,7 @@ def test_incorrect_case_file_index(data):
 @pytest.mark.network
 def test_finder_detects_latest_already_satisfied_find_links(data):
     """Test PackageFinder detects latest already satisfied using find-links"""
-    req = InstallRequirement.from_line('simple', None)
+    req = install_req_from_line('simple', None)
     # the latest simple in local pkgs is 3.0
     latest_version = "3.0"
     satisfied_by = Mock(
@@ -96,7 +96,7 @@ def test_finder_detects_latest_already_satisfied_find_links(data):
 @pytest.mark.network
 def test_finder_detects_latest_already_satisfied_pypi_links():
     """Test PackageFinder detects latest already satisfied using pypi links"""
-    req = InstallRequirement.from_line('initools', None)
+    req = install_req_from_line('initools', None)
     # the latest initools on pypi is 0.3.1
     latest_version = "0.3.1"
     satisfied_by = Mock(
@@ -123,7 +123,7 @@ class TestWheel:
         """
         caplog.set_level(logging.DEBUG)
 
-        req = InstallRequirement.from_line("invalid")
+        req = install_req_from_line("invalid")
         # data.find_links contains "invalid.whl", which is an invalid wheel
         finder = PackageFinder(
             [data.find_links],
@@ -148,7 +148,7 @@ class TestWheel:
             lambda **kw: [("py1", "none", "any")],
         )
 
-        req = InstallRequirement.from_line("simple.dist")
+        req = install_req_from_line("simple.dist")
         finder = PackageFinder(
             [data.find_links],
             [],
@@ -169,7 +169,7 @@ class TestWheel:
             lambda **kw: [('py2', 'none', 'any')],
         )
 
-        req = InstallRequirement.from_line("simple.dist")
+        req = install_req_from_line("simple.dist")
         finder = PackageFinder(
             [data.find_links],
             [],
@@ -185,7 +185,7 @@ class TestWheel:
         Test wheels have priority over sdists.
         `test_link_sorting` also covers this at lower level
         """
-        req = InstallRequirement.from_line("priority")
+        req = install_req_from_line("priority")
         finder = PackageFinder(
             [data.find_links],
             [],
@@ -199,7 +199,7 @@ class TestWheel:
         Test existing install has priority over wheels.
         `test_link_sorting` also covers this at a lower level
         """
-        req = InstallRequirement.from_line('priority', None)
+        req = install_req_from_line('priority', None)
         latest_version = "1.0"
         satisfied_by = Mock(
             location="/path",
@@ -284,7 +284,7 @@ class TestWheel:
 
 def test_finder_priority_file_over_page(data):
     """Test PackageFinder prefers file links over equivalent page links"""
-    req = InstallRequirement.from_line('gmpy==1.15', None)
+    req = install_req_from_line('gmpy==1.15', None)
     finder = PackageFinder(
         [data.find_links],
         ["http://pypi.org/simple/"],
@@ -304,7 +304,7 @@ def test_finder_deplink():
     """
     Test PackageFinder with dependency links only
     """
-    req = InstallRequirement.from_line('gmpy==1.15', None)
+    req = install_req_from_line('gmpy==1.15', None)
     finder = PackageFinder(
         [],
         [],
@@ -323,7 +323,7 @@ def test_finder_priority_page_over_deplink():
     """
     Test PackageFinder prefers page links over equivalent dependency links
     """
-    req = InstallRequirement.from_line('pip==1.5.6', None)
+    req = install_req_from_line('pip==1.5.6', None)
     finder = PackageFinder(
         [],
         ["https://pypi.org/simple/"],
@@ -346,7 +346,7 @@ def test_finder_priority_page_over_deplink():
 
 def test_finder_priority_nonegg_over_eggfragments():
     """Test PackageFinder prefers non-egg links over "#egg=" links"""
-    req = InstallRequirement.from_line('bar==1.0', None)
+    req = install_req_from_line('bar==1.0', None)
     links = ['http://foo/bar.py#egg=bar-1.0', 'http://foo/bar-1.0.tar.gz']
 
     finder = PackageFinder(links, [], session=PipSession())
@@ -377,7 +377,7 @@ def test_finder_only_installs_stable_releases(data):
     Test PackageFinder only accepts stable versioned releases by default.
     """
 
-    req = InstallRequirement.from_line("bar", None)
+    req = install_req_from_line("bar", None)
 
     # using a local index (that has pre & dev releases)
     finder = PackageFinder([], [data.index_url("pre")], session=PipSession())
@@ -431,7 +431,7 @@ def test_finder_installs_pre_releases(data):
     Test PackageFinder finds pre-releases if asked to.
     """
 
-    req = InstallRequirement.from_line("bar", None)
+    req = install_req_from_line("bar", None)
 
     # using a local index (that has pre & dev releases)
     finder = PackageFinder(
@@ -471,7 +471,7 @@ def test_finder_installs_dev_releases(data):
     Test PackageFinder finds dev releases if asked to.
     """
 
-    req = InstallRequirement.from_line("bar", None)
+    req = install_req_from_line("bar", None)
 
     # using a local index (that has dev releases)
     finder = PackageFinder(
@@ -487,7 +487,7 @@ def test_finder_installs_pre_releases_with_version_spec():
     """
     Test PackageFinder only accepts stable versioned releases by default.
     """
-    req = InstallRequirement.from_line("bar>=0.0.dev0", None)
+    req = install_req_from_line("bar>=0.0.dev0", None)
     links = ["https://foo/bar-1.0.tar.gz", "https://foo/bar-2.0b1.tar.gz"]
 
     finder = PackageFinder(links, [], session=PipSession())
@@ -555,7 +555,7 @@ def test_get_index_urls_locations():
     finder = PackageFinder(
         [], ['file://index1/', 'file://index2'], session=PipSession())
     locations = finder._get_index_urls_locations(
-        InstallRequirement.from_line('Complex_Name').name)
+        install_req_from_line('Complex_Name').name)
     assert locations == ['file://index1/complex-name/',
                          'file://index2/complex-name/']
 
diff --git a/tests/unit/test_req.py b/tests/unit/test_req.py
index 30110f149..09941d0f9 100644
--- a/tests/unit/test_req.py
+++ b/tests/unit/test_req.py
@@ -18,7 +18,7 @@ from pip._internal.index import PackageFinder
 from pip._internal.operations.prepare import RequirementPreparer
 from pip._internal.req import InstallRequirement, RequirementSet
 from pip._internal.req.constructors import (
-    install_req_from_editable, parse_editable,
+    install_req_from_editable, install_req_from_line, parse_editable,
 )
 from pip._internal.req.req_file import process_line
 from pip._internal.req.req_tracker import RequirementTracker
@@ -68,7 +68,7 @@ class TestRequirementSet(object):
         os.makedirs(build_dir)
         open(os.path.join(build_dir, "setup.py"), 'w')
         reqset = RequirementSet()
-        req = InstallRequirement.from_line('simple')
+        req = install_req_from_line('simple')
         req.is_direct = True
         reqset.add_requirement(req)
         finder = PackageFinder([data.find_links], [], session=PipSession())
@@ -341,12 +341,12 @@ class TestInstallRequirement(object):
         """InstallRequirement should strip the fragment, but not the query."""
         url = 'http://foo.com/?p=bar.git;a=snapshot;h=v0.1;sf=tgz'
         fragment = '#egg=bar'
-        req = InstallRequirement.from_line(url + fragment)
+        req = install_req_from_line(url + fragment)
         assert req.link.url == url + fragment, req.link
 
     def test_unsupported_wheel_link_requirement_raises(self):
         reqset = RequirementSet()
-        req = InstallRequirement.from_line(
+        req = install_req_from_line(
             'https://whatever.com/peppercorn-0.4-py2.py3-bogus-any.whl',
         )
         assert req.link is not None
@@ -358,7 +358,7 @@ class TestInstallRequirement(object):
 
     def test_unsupported_wheel_local_file_requirement_raises(self, data):
         reqset = RequirementSet()
-        req = InstallRequirement.from_line(
+        req = install_req_from_line(
             data.packages.join('simple.dist-0.1-py1-none-invalid.whl'),
         )
         assert req.link is not None
@@ -369,32 +369,32 @@ class TestInstallRequirement(object):
             reqset.add_requirement(req)
 
     def test_installed_version_not_installed(self):
-        req = InstallRequirement.from_line('simple-0.1-py2.py3-none-any.whl')
+        req = install_req_from_line('simple-0.1-py2.py3-none-any.whl')
         assert req.installed_version is None
 
     def test_str(self):
-        req = InstallRequirement.from_line('simple==0.1')
+        req = install_req_from_line('simple==0.1')
         assert str(req) == 'simple==0.1'
 
     def test_repr(self):
-        req = InstallRequirement.from_line('simple==0.1')
+        req = install_req_from_line('simple==0.1')
         assert repr(req) == (
             '<InstallRequirement object: simple==0.1 editable=False>'
         )
 
     def test_invalid_wheel_requirement_raises(self):
         with pytest.raises(InvalidWheelFilename):
-            InstallRequirement.from_line('invalid.whl')
+            install_req_from_line('invalid.whl')
 
     def test_wheel_requirement_sets_req_attribute(self):
-        req = InstallRequirement.from_line('simple-0.1-py2.py3-none-any.whl')
+        req = install_req_from_line('simple-0.1-py2.py3-none-any.whl')
         assert isinstance(req.req, Requirement)
         assert str(req.req) == 'simple==0.1'
 
     def test_url_preserved_line_req(self):
         """Confirm the url is preserved in a non-editable requirement"""
         url = 'git+http://foo.com@ref#egg=foo'
-        req = InstallRequirement.from_line(url)
+        req = install_req_from_line(url)
         assert req.link.url == url
 
     def test_url_preserved_editable_req(self):
@@ -409,7 +409,7 @@ class TestInstallRequirement(object):
         '/path/to/foo.egg-info/'.replace('/', os.path.sep),
     ))
     def test_get_dist(self, path):
-        req = InstallRequirement.from_line('foo')
+        req = install_req_from_line('foo')
         req._egg_info_path = path
         dist = req.get_dist()
         assert isinstance(dist, pkg_resources.Distribution)
@@ -425,14 +425,14 @@ class TestInstallRequirement(object):
             # without spaces
             'mock3;python_version >= "3"',
         ):
-            req = InstallRequirement.from_line(line)
+            req = install_req_from_line(line)
             assert req.req.name == 'mock3'
             assert str(req.req.specifier) == ''
             assert str(req.markers) == 'python_version >= "3"'
 
     def test_markers_semicolon(self):
         # check that the markers can contain a semicolon
-        req = InstallRequirement.from_line('semicolon; os_name == "a; b"')
+        req = install_req_from_line('semicolon; os_name == "a; b"')
         assert req.req.name == 'semicolon'
         assert str(req.req.specifier) == ''
         assert str(req.markers) == 'os_name == "a; b"'
@@ -441,14 +441,14 @@ class TestInstallRequirement(object):
         # test "URL; markers" syntax
         url = 'http://foo.com/?p=bar.git;a=snapshot;h=v0.1;sf=tgz'
         line = '%s; python_version >= "3"' % url
-        req = InstallRequirement.from_line(line)
+        req = install_req_from_line(line)
         assert req.link.url == url, req.url
         assert str(req.markers) == 'python_version >= "3"'
 
         # without space, markers are part of the URL
         url = 'http://foo.com/?p=bar.git;a=snapshot;h=v0.1;sf=tgz'
         line = '%s;python_version >= "3"' % url
-        req = InstallRequirement.from_line(line)
+        req = install_req_from_line(line)
         assert req.link.url == line, req.url
         assert req.markers is None
 
@@ -459,7 +459,7 @@ class TestInstallRequirement(object):
             'sys_platform == %r' % sys.platform,
         ):
             line = 'name; ' + markers
-            req = InstallRequirement.from_line(line)
+            req = install_req_from_line(line)
             assert str(req.markers) == str(Marker(markers))
             assert req.match_markers()
 
@@ -469,7 +469,7 @@ class TestInstallRequirement(object):
             'sys_platform != %r' % sys.platform,
         ):
             line = 'name; ' + markers
-            req = InstallRequirement.from_line(line)
+            req = install_req_from_line(line)
             assert str(req.markers) == str(Marker(markers))
             assert not req.match_markers()
 
@@ -480,7 +480,7 @@ class TestInstallRequirement(object):
             'sys_platform == %r' % sys.platform,
         ):
             line = 'name; ' + markers
-            req = InstallRequirement.from_line(line, comes_from='')
+            req = install_req_from_line(line, comes_from='')
             assert str(req.markers) == str(Marker(markers))
             assert req.match_markers()
 
@@ -490,7 +490,7 @@ class TestInstallRequirement(object):
             'sys_platform != %r' % sys.platform,
         ):
             line = 'name; ' + markers
-            req = InstallRequirement.from_line(line, comes_from='')
+            req = install_req_from_line(line, comes_from='')
             assert str(req.markers) == str(Marker(markers))
             assert not req.match_markers()
 
@@ -498,7 +498,7 @@ class TestInstallRequirement(object):
         line = 'SomeProject[ex1,ex2]'
         filename = 'filename'
         comes_from = '-r %s (line %s)' % (filename, 1)
-        req = InstallRequirement.from_line(line, comes_from=comes_from)
+        req = install_req_from_line(line, comes_from=comes_from)
         assert len(req.extras) == 2
         assert req.extras == {'ex1', 'ex2'}
 
@@ -506,7 +506,7 @@ class TestInstallRequirement(object):
         line = 'git+https://url#egg=SomeProject[ex1,ex2]'
         filename = 'filename'
         comes_from = '-r %s (line %s)' % (filename, 1)
-        req = InstallRequirement.from_line(line, comes_from=comes_from)
+        req = install_req_from_line(line, comes_from=comes_from)
         assert len(req.extras) == 2
         assert req.extras == {'ex1', 'ex2'}
 
@@ -528,7 +528,7 @@ class TestInstallRequirement(object):
 
     def test_unexisting_path(self):
         with pytest.raises(InstallationError) as e:
-            InstallRequirement.from_line(
+            install_req_from_line(
                 os.path.join('this', 'path', 'does', 'not', 'exist'))
         err_msg = e.value.args[0]
         assert "Invalid requirement" in err_msg
@@ -536,14 +536,14 @@ class TestInstallRequirement(object):
 
     def test_single_equal_sign(self):
         with pytest.raises(InstallationError) as e:
-            InstallRequirement.from_line('toto=42')
+            install_req_from_line('toto=42')
         err_msg = e.value.args[0]
         assert "Invalid requirement" in err_msg
         assert "= is not a valid operator. Did you mean == ?" in err_msg
 
     def test_traceback(self):
         with pytest.raises(InstallationError) as e:
-            InstallRequirement.from_line('toto 42')
+            install_req_from_line('toto 42')
         err_msg = e.value.args[0]
         assert "Invalid requirement" in err_msg
         assert "\nTraceback " in err_msg
@@ -553,7 +553,7 @@ class TestInstallRequirement(object):
         with open(req_file_path, 'w') as req_file:
             req_file.write('pip\nsetuptools')
         with pytest.raises(InstallationError) as e:
-            InstallRequirement.from_line(req_file_path)
+            install_req_from_line(req_file_path)
         err_msg = e.value.args[0]
         assert "Invalid requirement" in err_msg
         assert "It looks like a path. It does exist." in err_msg
@@ -610,10 +610,10 @@ def test_parse_editable_local_extras(
 
 def test_exclusive_environment_markers():
     """Make sure RequirementSet accepts several excluding env markers"""
-    eq26 = InstallRequirement.from_line(
+    eq26 = install_req_from_line(
         "Django>=1.6.10,<1.7 ; python_version == '2.6'")
     eq26.is_direct = True
-    ne26 = InstallRequirement.from_line(
+    ne26 = install_req_from_line(
         "Django>=1.6.10,<1.8 ; python_version != '2.6'")
     ne26.is_direct = True
 
diff --git a/tests/unit/test_req_file.py b/tests/unit/test_req_file.py
index 664196b03..1d7c48b7f 100644
--- a/tests/unit/test_req_file.py
+++ b/tests/unit/test_req_file.py
@@ -12,12 +12,13 @@ from pip._internal.exceptions import (
     InstallationError, RequirementsFileParseError,
 )
 from pip._internal.index import PackageFinder
-from pip._internal.req.constructors import install_req_from_editable
+from pip._internal.req.constructors import (
+    install_req_from_editable, install_req_from_line,
+)
 from pip._internal.req.req_file import (
     break_args_options, ignore_comments, join_lines, parse_requirements,
     preprocess, process_line, skip_regex,
 )
-from pip._internal.req.req_install import InstallRequirement
 from tests.lib import requirements_file
 
 
@@ -193,14 +194,14 @@ class TestProcessLine(object):
         line = 'SomeProject'
         filename = 'filename'
         comes_from = '-r %s (line %s)' % (filename, 1)
-        req = InstallRequirement.from_line(line, comes_from=comes_from)
+        req = install_req_from_line(line, comes_from=comes_from)
         assert repr(list(process_line(line, filename, 1))[0]) == repr(req)
 
     def test_yield_line_constraint(self):
         line = 'SomeProject'
         filename = 'filename'
         comes_from = '-c %s (line %s)' % (filename, 1)
-        req = InstallRequirement.from_line(
+        req = install_req_from_line(
             line, comes_from=comes_from, constraint=True)
         found_req = list(process_line(line, filename, 1, constraint=True))[0]
         assert repr(found_req) == repr(req)
@@ -210,7 +211,7 @@ class TestProcessLine(object):
         line = 'SomeProject >= 2'
         filename = 'filename'
         comes_from = '-r %s (line %s)' % (filename, 1)
-        req = InstallRequirement.from_line(line, comes_from=comes_from)
+        req = install_req_from_line(line, comes_from=comes_from)
         assert repr(list(process_line(line, filename, 1))[0]) == repr(req)
         assert str(req.req.specifier) == '>=2'
 
@@ -235,7 +236,7 @@ class TestProcessLine(object):
 
     def test_nested_requirements_file(self, monkeypatch):
         line = '-r another_file'
-        req = InstallRequirement.from_line('SomeProject')
+        req = install_req_from_line('SomeProject')
         import pip._internal.req.req_file
 
         def stub_parse_requirements(req_url, finder, comes_from, options,
@@ -248,7 +249,7 @@ class TestProcessLine(object):
 
     def test_nested_constraints_file(self, monkeypatch):
         line = '-c another_file'
-        req = InstallRequirement.from_line('SomeProject')
+        req = install_req_from_line('SomeProject')
         import pip._internal.req.req_file
 
         def stub_parse_requirements(req_url, finder, comes_from, options,
diff --git a/tests/unit/test_req_install.py b/tests/unit/test_req_install.py
index 17af7d5f5..f4a6e94a1 100644
--- a/tests/unit/test_req_install.py
+++ b/tests/unit/test_req_install.py
@@ -3,6 +3,7 @@ import tempfile
 
 import pytest
 
+from pip._internal.req.constructors import install_req_from_line
 from pip._internal.req.req_install import InstallRequirement
 
 
@@ -36,7 +37,7 @@ class TestInstallRequirementBuildDirectory(object):
         with open(setup_py_path, 'w') as f:
             f.write('')
 
-        requirement = InstallRequirement.from_line(
+        requirement = install_req_from_line(
             str(install_dir).replace(os.sep, os.altsep or os.sep)
         )