Add failing tests for issue pypa#1139 re: --force-reinstall.

Author: cjerdonek

tests/functional/test_install_force_reinstall.py

@@ -0,0 +1,45 @@
+import pytest
+
+from tests.lib import assert_all_changes, pyversion_tuple
+
+
+def check_installed_version(script, package, expected):
+    # Python 3.3 emits a "Python 3.3 support has been deprecated" warning.
+    expect_stderr = (pyversion_tuple[:2] == (3, 3))
+    result = script.run('pip', 'show', package, expect_stderr=expect_stderr)
+    lines = result.stdout.splitlines()
+    for line in lines:
+        if line.startswith('Version: '):
+            version = line.split()[-1]
+            break
+    assert version == expected, 'version {} != {}'.format(version, expected)
+
+
+@pytest.mark.network
+def test_force_reinstall_with_no_version_specifier(script):
+    """
+    Check --force-reinstall when there is no version specifier and the
+    installed version is not the newest version.
+    """
+    result = script.pip('install', 'INITools==0.2')
+    check_installed_version(script, 'initools', '0.2')
+    result2 = script.pip('install', '--force-reinstall', 'INITools')
+    assert result2.files_updated, 'force-reinstall failed'
+    check_installed_version(script, 'initools', '0.3.1')
+    result3 = script.pip('uninstall', 'initools', '-y', expect_error=True)
+    assert_all_changes(result, result3, [script.venv / 'build', 'cache'])
+
+
+@pytest.mark.network
+def test_force_reinstall_with_same_version_specifier(script):
+    """
+    Check --force-reinstall when the version specifier equals the installed
+    version and the installed version is not the newest version.
+    """
+    result = script.pip('install', 'INITools==0.2')
+    check_installed_version(script, 'initools', '0.2')
+    result2 = script.pip('install', '--force-reinstall', 'INITools==0.2')
+    assert result2.files_updated, 'force-reinstall failed'
+    check_installed_version(script, 'initools', '0.2')
+    result3 = script.pip('uninstall', 'initools', '-y', expect_error=True)
+    assert_all_changes(result, result3, [script.venv / 'build', 'cache'])