Add unit test which demonstrates bug 705986

This USE suggestion appears to prevent application of || preference
adjustment to solve the cycle (pypy-exe-bin would solve it):

 * Error: circular dependencies:

(dev-python/pypy-exe-7.3.0:7.3.0/7.3.0::test_repo, ebuild scheduled for merge) depends on
 (dev-python/pypy-7.3.0:0/73::test_repo, ebuild scheduled for merge) (buildtime)
  (dev-python/pypy-exe-7.3.0:7.3.0/7.3.0::test_repo, ebuild scheduled for merge) (buildtime)

It might be possible to break this cycle
by applying the following change:
- dev-python/pypy-exe-7.3.0 (Change USE: +low-memory)

Meanwhile, an explicit pypy-exe-bin argument adjusts the || preference
and breaks the cycle:

$ emerge -pq pypy pypy-exe-bin
[ebuild  N     ] dev-python/pypy-exe-bin-7.3.0
[ebuild  N     ] dev-python/pypy-7.3.0

Bug: https://bugs.gentoo.org/705986
Signed-off-by: Zac Medico <zmedico@gentoo.org>

1 files changed, 48 insertions, 0 deletions

diff --git a/lib/portage/tests/resolver/test_circular_choices.py b/lib/portage/tests/resolver/test_circular_choices.py
index a5c10b476..968677a46 100644
--- a/lib/portage/tests/resolver/test_circular_choices.py
+++ b/lib/portage/tests/resolver/test_circular_choices.py
@@ -160,3 +160,51 @@ class VirtualCircularChoicesTestCase(TestCase):
 				self.assertEqual(test_case.test_success, True, test_case.fail_msg)
 		finally:
 			playground.cleanup()
+
+
+class CircularPypyExeTestCase(TestCase):
+	def testCircularPypyExe(self):
+
+		ebuilds = {
+			'dev-python/pypy-7.3.0': {
+				'EAPI': '7',
+				'SLOT' : '0/73',
+				'DEPEND': '|| ( dev-python/pypy-exe dev-python/pypy-exe-bin )'
+			},
+			'dev-python/pypy-exe-7.3.0': {
+				'EAPI': '7',
+				'IUSE': 'low-memory',
+				'SLOT' : '7.3.0',
+				'BDEPEND': '!low-memory? ( dev-python/pypy )'
+			},
+			'dev-python/pypy-exe-bin-7.3.0': {
+				'EAPI': '7',
+				'SLOT' : '7.3.0',
+			},
+		}
+
+		test_cases = (
+			# Demonstrate bug 705986, where a USE change suggestion is given
+			# even though an || preference adjustment is available.
+			ResolverPlaygroundTestCase(
+				['dev-python/pypy'],
+				circular_dependency_solutions = {'dev-python/pypy-7.3.0': {frozenset({('low-memory', True)})}},
+				success = False,
+			),
+			# Demonstrate explicit pypy-exe-bin argument used as a workaround
+			# for bug 705986.
+			ResolverPlaygroundTestCase(
+				['dev-python/pypy', 'dev-python/pypy-exe-bin'],
+				mergelist=['dev-python/pypy-exe-bin-7.3.0', 'dev-python/pypy-7.3.0'],
+				success = True,
+			),
+		)
+
+		playground = ResolverPlayground(ebuilds=ebuilds, debug=False)
+		try:
+			for test_case in test_cases:
+				playground.run_TestCase(test_case)
+				self.assertEqual(test_case.test_success, True, test_case.fail_msg)
+		finally:
+			playground.debug = False
+			playground.cleanup()