solver: Fix bug where some items were not emitted

Sometimes the solver would correctly compute which items are grouped
together, but then fail to emit some groups.  This is trivially
fixable by forcing an update of "before" + "after" relations.
Admittedly, this looks unnecessary, so it may just be hiding the bug.

Nonetheless, the change makes the new test_solver_simple_scc test
produce the expected result.

Signed-off-by: Niels Thykier <niels@thykier.net>

britney2/installability/solver.py

@@ -221,6 +221,14 @@ class InstallabilitySolver(InstallabilityTester):
             order[node]['before'] = nbefore
             order[node]['after'] = nafter
 
+        for com in comps:
+            scc_id = com[0]
+
+            for other_scc_id in order[scc_id]['before']:
+                order[other_scc_id]['after'].add(scc_id)
+            for other_scc_id in order[scc_id]['after']:
+                order[other_scc_id]['before'].add(scc_id)
+
         if debug_solver:  # pragma: no cover
             print("N: -- PARTIAL ORDER --")
 

tests/test_inst_tester.py

@@ -412,6 +412,57 @@ class TestInstTester(unittest.TestCase):
         assert universe.stats.eqv_table_reduced_to_one == 0
         assert universe.stats.eqv_table_reduced_by_zero == 1
 
+    def test_solver_simple_scc(self):
+        builder = new_pkg_universe_builder()
+
+        # SCC 1
+        pkga = builder.new_package('pkg-a').not_in_testing()
+        pkgb = builder.new_package('pkg-b').not_in_testing()
+        pkgc = builder.new_package('pkg-c').not_in_testing()
+
+        # SSC 2
+        pkgd = builder.new_package('pkg-d').not_in_testing()
+        pkge = builder.new_package('pkg-e').not_in_testing()
+        pkgf = builder.new_package('pkg-f').not_in_testing()
+        pkgg = builder.new_package('pkg-g').not_in_testing()
+        pkgh = builder.new_package('pkg-h').not_in_testing()
+
+        # SSC 3
+        pkgi = builder.new_package('pkg-i').not_in_testing()
+
+        # SSC 1 dependencies
+        pkga.depends_on(pkgb)
+        pkgb.depends_on(pkgc).depends_on(pkgd)
+        pkgc.depends_on(pkga).depends_on(pkge)
+
+        # SSC 2 dependencies
+        pkgd.depends_on(pkgf)
+        pkge.depends_on(pkgg).depends_on(pkgd)
+        pkgf.depends_on(pkgh)
+        pkgg.depends_on(pkgh)
+        pkgh.depends_on(pkge).depends_on(pkgi)
+
+        universe = builder.build()
+        expected = [
+            # SSC 3 first
+            {pkgi.pkg_id.package_name},
+            # Then SSC 2
+            {pkgd.pkg_id.package_name, pkge.pkg_id.package_name, pkgf.pkg_id.package_name,
+             pkgg.pkg_id.package_name, pkgh.pkg_id.package_name},
+            # Finally SSC 1
+            {pkga.pkg_id.package_name, pkgb.pkg_id.package_name, pkgc.pkg_id.package_name},
+        ]
+        groups = []
+        for ssc in expected:
+            for node in ssc:
+                groups.append((node, {builder.pkg_id(node)}, {}))
+
+        actual = [set(x) for x in universe.solve_groups(groups)]
+        print("EXPECTED: %s" % str(expected))
+        print("ACTUAL  : %s" % str(actual))
+        assert expected == actual
+
+
 if __name__ == '__main__':
     unittest.main()