refactor: extract NATS.Server.Raft.Tests project
Move 43 Raft consensus test files (8 root-level + 35 in Raft/ subfolder) from NATS.Server.Tests into a dedicated NATS.Server.Raft.Tests project. Update namespaces, add InternalsVisibleTo, and fix timing/exception handling issues in moved test files.
This commit is contained in:
Joseph Doherty
300
tests/NATS.Server.Raft.Tests/Raft/RaftPreVoteTests.cs
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300
tests/NATS.Server.Raft.Tests/Raft/RaftPreVoteTests.cs
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using NATS.Server.Raft;
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namespace NATS.Server.Raft.Tests.Raft;
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/// <summary>
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/// Tests for B6: Pre-Vote Protocol.
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/// Go reference: raft.go:1600-1700 (pre-vote logic).
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/// Pre-vote prevents partitioned nodes from disrupting the cluster by
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/// incrementing their term without actually winning an election.
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/// </summary>
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public class RaftPreVoteTests
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{
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// -- Helpers --
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private static (RaftNode[] nodes, InMemoryRaftTransport transport) CreateCluster(int size)
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{
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var transport = new InMemoryRaftTransport();
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var nodes = Enumerable.Range(1, size)
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.Select(i => new RaftNode($"n{i}", transport))
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.ToArray();
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foreach (var node in nodes)
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{
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transport.Register(node);
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node.ConfigureCluster(nodes);
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}
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return (nodes, transport);
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}
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private static RaftNode ElectLeader(RaftNode[] nodes)
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{
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var candidate = nodes[0];
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candidate.StartElection(nodes.Length);
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foreach (var voter in nodes.Skip(1))
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candidate.ReceiveVote(voter.GrantVote(candidate.Term, candidate.Id), nodes.Length);
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return candidate;
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}
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// -- Wire format tests --
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[Fact]
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public void PreVote_request_encoding_roundtrip()
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{
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var request = new RaftPreVoteRequestWire(
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Term: 5,
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LastTerm: 4,
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LastIndex: 100,
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CandidateId: "n1");
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var encoded = request.Encode();
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encoded.Length.ShouldBe(RaftWireConstants.VoteRequestLen); // 32 bytes
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var decoded = RaftPreVoteRequestWire.Decode(encoded);
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decoded.Term.ShouldBe(5UL);
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decoded.LastTerm.ShouldBe(4UL);
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decoded.LastIndex.ShouldBe(100UL);
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decoded.CandidateId.ShouldBe("n1");
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}
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[Fact]
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public void PreVote_response_encoding_roundtrip()
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{
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var response = new RaftPreVoteResponseWire(
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Term: 5,
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PeerId: "n2",
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Granted: true);
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var encoded = response.Encode();
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encoded.Length.ShouldBe(RaftWireConstants.VoteResponseLen); // 17 bytes
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var decoded = RaftPreVoteResponseWire.Decode(encoded);
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decoded.Term.ShouldBe(5UL);
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decoded.PeerId.ShouldBe("n2");
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decoded.Granted.ShouldBeTrue();
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}
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[Fact]
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public void PreVote_response_denied_roundtrip()
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{
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var response = new RaftPreVoteResponseWire(Term: 3, PeerId: "n3", Granted: false);
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var decoded = RaftPreVoteResponseWire.Decode(response.Encode());
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decoded.Granted.ShouldBeFalse();
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decoded.PeerId.ShouldBe("n3");
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decoded.Term.ShouldBe(3UL);
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}
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[Fact]
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public void PreVote_request_decode_throws_on_wrong_length()
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{
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Should.Throw<ArgumentException>(() =>
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RaftPreVoteRequestWire.Decode(new byte[10]));
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}
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[Fact]
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public void PreVote_response_decode_throws_on_wrong_length()
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{
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Should.Throw<ArgumentException>(() =>
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RaftPreVoteResponseWire.Decode(new byte[10]));
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}
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// -- RequestPreVote logic tests --
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[Fact]
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public void PreVote_granted_when_candidate_log_is_up_to_date()
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{
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// Go reference: raft.go pre-vote grants when candidate log >= voter log
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var node = new RaftNode("voter");
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node.Log.Append(1, "cmd-1"); // voter has entry at index 1, term 1
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// Candidate has same term and same or higher index: should grant
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var granted = node.RequestPreVote(
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term: (ulong)node.Term,
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lastTerm: 1,
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lastIndex: 1,
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candidateId: "candidate");
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granted.ShouldBeTrue();
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}
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[Fact]
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public void PreVote_granted_when_candidate_has_higher_term_log()
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{
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var node = new RaftNode("voter");
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node.Log.Append(1, "cmd-1"); // voter: term 1, index 1
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// Candidate has higher last term: should grant
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var granted = node.RequestPreVote(
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term: 0,
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lastTerm: 2,
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lastIndex: 1,
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candidateId: "candidate");
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granted.ShouldBeTrue();
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}
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[Fact]
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public void PreVote_denied_when_candidate_log_is_stale()
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{
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// Go reference: raft.go pre-vote denied when candidate log behind voter
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var node = new RaftNode("voter");
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node.TermState.CurrentTerm = 2;
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node.Log.Append(2, "cmd-1");
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node.Log.Append(2, "cmd-2"); // voter: term 2, index 2
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// Candidate has lower last term: should deny
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var granted = node.RequestPreVote(
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term: 2,
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lastTerm: 1,
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lastIndex: 5,
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candidateId: "candidate");
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granted.ShouldBeFalse();
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}
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[Fact]
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public void PreVote_denied_when_candidate_term_behind()
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{
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var node = new RaftNode("voter");
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node.TermState.CurrentTerm = 5;
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// Candidate's term is behind the voter's current term
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var granted = node.RequestPreVote(
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term: 3,
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lastTerm: 3,
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lastIndex: 100,
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candidateId: "candidate");
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granted.ShouldBeFalse();
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}
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[Fact]
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public void PreVote_granted_for_empty_logs()
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{
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// Both node and candidate have empty logs: grant
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var node = new RaftNode("voter");
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var granted = node.RequestPreVote(
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term: 0,
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lastTerm: 0,
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lastIndex: 0,
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candidateId: "candidate");
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granted.ShouldBeTrue();
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}
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// -- Pre-vote integration with election flow --
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[Fact]
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public void Successful_prevote_leads_to_real_election()
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{
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// Go reference: after pre-vote success, proceed to real election with term increment
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var (nodes, _) = CreateCluster(3);
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var candidate = nodes[0];
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var termBefore = candidate.Term;
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// With pre-vote enabled, CampaignWithPreVote should succeed (all peers have equal logs)
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// and then start a real election (incrementing term)
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candidate.PreVoteEnabled = true;
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candidate.CampaignWithPreVote();
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// Term should have been incremented by the real election
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candidate.Term.ShouldBe(termBefore + 1);
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candidate.Role.ShouldBe(RaftRole.Candidate);
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}
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[Fact]
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public void Failed_prevote_does_not_increment_term()
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{
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// Go reference: failed pre-vote stays follower, doesn't disrupt cluster
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var (nodes, _) = CreateCluster(3);
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var candidate = nodes[0];
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// Give the other nodes higher-term logs so pre-vote will be denied
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nodes[1].TermState.CurrentTerm = 10;
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nodes[1].Log.Append(10, "advanced-cmd");
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nodes[2].TermState.CurrentTerm = 10;
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nodes[2].Log.Append(10, "advanced-cmd");
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var termBefore = candidate.Term;
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candidate.PreVoteEnabled = true;
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candidate.CampaignWithPreVote();
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// Term should NOT have been incremented — pre-vote failed
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candidate.Term.ShouldBe(termBefore);
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candidate.Role.ShouldBe(RaftRole.Follower);
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}
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[Fact]
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public void PreVote_disabled_goes_directly_to_election()
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{
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// When PreVoteEnabled is false, skip pre-vote and go straight to election
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var (nodes, _) = CreateCluster(3);
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var candidate = nodes[0];
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var termBefore = candidate.Term;
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candidate.PreVoteEnabled = false;
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candidate.CampaignWithPreVote();
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// Should have gone directly to election, incrementing term
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candidate.Term.ShouldBe(termBefore + 1);
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candidate.Role.ShouldBe(RaftRole.Candidate);
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}
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[Fact]
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public void Partitioned_node_with_stale_term_does_not_disrupt_via_prevote()
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{
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// Go reference: pre-vote prevents partitioned nodes from disrupting the cluster.
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// A node with a stale term that reconnects should fail the pre-vote round
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// and NOT increment its term, which would force other nodes to step down.
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var (nodes, _) = CreateCluster(3);
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// Simulate: n1 was partitioned and has term 0, others advanced to term 5
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nodes[1].TermState.CurrentTerm = 5;
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nodes[1].Log.Append(5, "cmd-a");
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nodes[1].Log.Append(5, "cmd-b");
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nodes[2].TermState.CurrentTerm = 5;
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nodes[2].Log.Append(5, "cmd-a");
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nodes[2].Log.Append(5, "cmd-b");
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var partitioned = nodes[0];
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partitioned.PreVoteEnabled = true;
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var termBefore = partitioned.Term;
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// Pre-vote should fail because the partitioned node has a stale log
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partitioned.CampaignWithPreVote();
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// The partitioned node should NOT have incremented its term
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partitioned.Term.ShouldBe(termBefore);
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partitioned.Role.ShouldBe(RaftRole.Follower);
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}
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[Fact]
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public void PreVote_enabled_by_default()
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{
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var node = new RaftNode("n1");
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node.PreVoteEnabled.ShouldBeTrue();
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}
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[Fact]
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public void StartPreVote_returns_true_when_majority_grants()
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{
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// All nodes have empty, equal logs: pre-vote should succeed
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var (nodes, _) = CreateCluster(3);
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var candidate = nodes[0];
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var result = candidate.StartPreVote();
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result.ShouldBeTrue();
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}
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[Fact]
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public void StartPreVote_returns_false_when_majority_denies()
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{
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var (nodes, _) = CreateCluster(3);
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var candidate = nodes[0];
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// Make majority have more advanced logs
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nodes[1].TermState.CurrentTerm = 10;
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nodes[1].Log.Append(10, "cmd");
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nodes[2].TermState.CurrentTerm = 10;
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nodes[2].Log.Append(10, "cmd");
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var result = candidate.StartPreVote();
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result.ShouldBeFalse();
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}
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}
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