identify and ignore (for now) the common idiom of (InputCommunities -…

… Exp) in the translation of a community set expression
batfish · Mar 30, 2021 · cfe022b · cfe022b
1 parent 02c5d99
commit cfe022b
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diff --git a/...cts/minesweeper/src/main/java/org/batfish/minesweeper/bdd/SetCommunitiesVarCollector.java b/...cts/minesweeper/src/main/java/org/batfish/minesweeper/bdd/SetCommunitiesVarCollector.java
@@ -34,7 +34,14 @@ public Set<CommunityVar> visitCommunityExprsSet(
   @Override
   public Set<CommunityVar> visitCommunitySetDifference(
       CommunitySetDifference communitySetDifference, Configuration arg) {
-    throw new UnsupportedOperationException("Community set differences are not supported");
+    if (communitySetDifference.getInitial().equals(InputCommunities.instance())) {
+      // a common pattern is to remove specific input communities (e.g. all standard ones)
+      // before adding new ones.
+      // TODO: handle this idiom properly rather than just ignoring it
+      return ImmutableSet.of();
+    } else {
+      throw new UnsupportedOperationException("Community set differences are not supported");
+    }
   }
 
   @Override

diff --git a/...minesweeper/src/test/java/org/batfish/minesweeper/bdd/SetCommunitiesVarCollectorTest.java b/...minesweeper/src/test/java/org/batfish/minesweeper/bdd/SetCommunitiesVarCollectorTest.java
@@ -9,11 +9,14 @@
 import org.batfish.datamodel.ConfigurationFormat;
 import org.batfish.datamodel.NetworkFactory;
 import org.batfish.datamodel.bgp.community.StandardCommunity;
+import org.batfish.datamodel.routing_policy.communities.AllStandardCommunities;
 import org.batfish.datamodel.routing_policy.communities.CommunityExprsSet;
 import org.batfish.datamodel.routing_policy.communities.CommunitySet;
+import org.batfish.datamodel.routing_policy.communities.CommunitySetDifference;
 import org.batfish.datamodel.routing_policy.communities.CommunitySetExprReference;
 import org.batfish.datamodel.routing_policy.communities.CommunitySetReference;
 import org.batfish.datamodel.routing_policy.communities.CommunitySetUnion;
+import org.batfish.datamodel.routing_policy.communities.InputCommunities;
 import org.batfish.datamodel.routing_policy.communities.LiteralCommunitySet;
 import org.batfish.datamodel.routing_policy.communities.StandardCommunityHighLowExprs;
 import org.batfish.datamodel.routing_policy.expr.LiteralInt;
@@ -55,6 +58,16 @@ public void testVisitCommunityExprsSet() {
     assertEquals(ImmutableSet.of(cvar1, cvar2), result);
   }
 
+  @Test
+  public void testVisitCommunitySetDifference() {
+    CommunitySetDifference csd =
+        new CommunitySetDifference(InputCommunities.instance(), AllStandardCommunities.instance());
+
+    Set<CommunityVar> result = _varCollector.visitCommunitySetDifference(csd, _baseConfig);
+
+    assertEquals(ImmutableSet.of(), result);
+  }
+
   @Test
   public void testVisitCommunitySetExprReference() {
     String name = "name";