Add unit test coverage for our onion peer eviction protection

Author: jonatack

src/test/net_peer_eviction_tests.cpp

@@ -110,7 +110,29 @@ BOOST_AUTO_TEST_CASE(peer_protection_test)
         /* unprotected_peer_ids */ {0, 1, 2, 3, 4, 5},
         random_context));
 
-    // Test protection of localhost peers...
+    // Test protection of onion and localhost peers...
+
+    // Expect 1/4 onion peers to be protected from eviction,
+    // independently of other characteristics.
+    BOOST_CHECK(IsProtected(
+        num_peers, [](NodeEvictionCandidate& c) {
+            c.m_is_onion = (c.id == 3 || c.id == 8 || c.id == 9);
+        },
+        /* protected_peer_ids */ {3, 8, 9},
+        /* unprotected_peer_ids */ {},
+        random_context));
+
+    // Expect 1/4 onion peers and 1/4 of the others to be protected
+    // from eviction, sorted by longest uptime (lowest nTimeConnected).
+    BOOST_CHECK(IsProtected(
+        num_peers, [](NodeEvictionCandidate& c) {
+            c.nTimeConnected = c.id;
+            c.m_is_local = false;
+            c.m_is_onion = (c.id == 3 || c.id > 7);
+        },
+        /* protected_peer_ids */ {0, 1, 2, 3, 8, 9},
+        /* unprotected_peer_ids */ {4, 5, 6, 7, 10, 11},
+        random_context));
 
     // Expect 1/4 localhost peers to be protected from eviction,
     // if no onion peers.
@@ -134,6 +156,78 @@ BOOST_AUTO_TEST_CASE(peer_protection_test)
         /* protected_peer_ids */ {0, 1, 2, 7, 8, 9},
         /* unprotected_peer_ids */ {3, 4, 5, 6, 10, 11},
         random_context));
+
+    // Combined test: expect 1/4 onion and 2 localhost peers to be protected
+    // from eviction, sorted by longest uptime.
+    BOOST_CHECK(IsProtected(
+        num_peers, [](NodeEvictionCandidate& c) {
+            c.nTimeConnected = c.id;
+            c.m_is_onion = (c.id == 0 || c.id == 5 || c.id == 10);
+            c.m_is_local = (c.id == 1 || c.id == 9 || c.id == 11);
+        },
+        /* protected_peer_ids */ {0, 1, 2, 5, 9, 10},
+        /* unprotected_peer_ids */ {3, 4, 6, 7, 8, 11},
+        random_context));
+
+    // Combined test: expect having only 1 onion to allow allocating the
+    // remaining 2 of the 1/4 to localhost peers, sorted by longest uptime.
+    BOOST_CHECK(IsProtected(
+        num_peers + 4, [](NodeEvictionCandidate& c) {
+            c.nTimeConnected = c.id;
+            c.m_is_onion = (c.id == 15);
+            c.m_is_local = (c.id > 6 && c.id < 11);
+        },
+        /* protected_peer_ids */ {0, 1, 2, 3, 7, 8, 9, 15},
+        /* unprotected_peer_ids */ {4, 5, 6, 10, 11, 12, 13, 14},
+        random_context));
+
+    // Combined test: expect 2 onions (< 1/4) to allow allocating the minimum 2
+    // localhost peers, sorted by longest uptime.
+    BOOST_CHECK(IsProtected(
+        num_peers, [](NodeEvictionCandidate& c) {
+            c.nTimeConnected = c.id;
+            c.m_is_onion = (c.id == 7 || c.id == 9);
+            c.m_is_local = (c.id == 6 || c.id == 11);
+        },
+        /* protected_peer_ids */ {0, 1, 6, 7, 9, 11},
+        /* unprotected_peer_ids */ {2, 3, 4, 5, 8, 10},
+        random_context));
+
+    // Combined test: when > 1/4, expect max 1/4 onion and 2 localhost peers
+    // to be protected from eviction, sorted by longest uptime.
+    BOOST_CHECK(IsProtected(
+        num_peers, [](NodeEvictionCandidate& c) {
+            c.nTimeConnected = c.id;
+            c.m_is_onion = (c.id > 3 && c.id < 8);
+            c.m_is_local = (c.id > 7);
+        },
+        /* protected_peer_ids */ {0, 4, 5, 6, 8, 9},
+        /* unprotected_peer_ids */ {1, 2, 3, 7, 10, 11},
+        random_context));
+
+    // Combined test: idem > 1/4 with only 8 peers: expect 2 onion and 2
+    // localhost peers (1/4 + 2) to be protected, sorted by longest uptime.
+    BOOST_CHECK(IsProtected(
+        8, [](NodeEvictionCandidate& c) {
+            c.nTimeConnected = c.id;
+            c.m_is_onion = (c.id > 1 && c.id < 5);
+            c.m_is_local = (c.id > 4);
+        },
+        /* protected_peer_ids */ {2, 3, 5, 6},
+        /* unprotected_peer_ids */ {0, 1, 4, 7},
+        random_context));
+
+    // Combined test: idem > 1/4 with only 6 peers: expect 1 onion peer and no
+    // localhost peers (1/4 + 0) to be protected, sorted by longest uptime.
+    BOOST_CHECK(IsProtected(
+        6, [](NodeEvictionCandidate& c) {
+            c.nTimeConnected = c.id;
+            c.m_is_onion = (c.id == 4 || c.id == 5);
+            c.m_is_local = (c.id == 3);
+        },
+        /* protected_peer_ids */ {0, 1, 4},
+        /* unprotected_peer_ids */ {2, 3, 5},
+        random_context));
 }
 
 // Returns true if any of the node ids in node_ids are selected for eviction.