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LightTests.tla
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LightTests.tla
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------------------------- MODULE LightTests ---------------------------
EXTENDS Lightclient_003_draft
(* The light client history, which is the function mapping states 0..nprobes to the record with fields:
- verified: the latest verified block in the previous state
- current: the block that is being checked in the previous state
- now: the time point in the previous state
- verdict: the light client verdict in the previous state
*)
VARIABLE
\* @type: Int -> [verified: BLOCK, current: BLOCK, now: Int, verdict: Str];
history
\* This predicate extends the LightClient Init predicate with history tracking
InitTest ==
/\ Init
/\ history = [ n \in {0} |->
[ verified |-> prevVerified, current |-> prevCurrent, now |-> prevNow, verdict |-> prevVerdict ]]
\* This predicate extends the LightClient Next predicate with history tracking
NextTest ==
/\ Next
/\ history' = [ n \in DOMAIN history \union {nprobes'} |->
IF n = nprobes' THEN
[ verified |-> prevVerified', current |-> prevCurrent', now |-> prevNow', verdict |-> prevVerdict' ]
ELSE history[n]
]
\* Some useful operators for writing tests
LightBlock(st) == history[st].current
Height(st) == history[st].current.header.height
ValSet(st) == LightBlock(st).header.VS
ValCommits(st) == LightBlock(st).Commits
\* Test an execution that finishes with failure
TestFailure ==
/\ state = "finishedFailure"
/\ Cardinality(DOMAIN fetchedLightBlocks) = TARGET_HEIGHT
\* Test an execution that finishes with success
TestSuccess ==
/\ state = "finishedSuccess"
/\ Cardinality(DOMAIN fetchedLightBlocks) = TARGET_HEIGHT
\* This test never produces a counterexample; so the model should be corrected
TestFailedTrustingPeriod ==
\E s \in DOMAIN history :
history[s].verdict = "FAILED_TRUSTING_PERIOD"
TwoNotEnoughTrust ==
\E s1, s2 \in DOMAIN history :
/\ s1 /= s2
/\ history[s1].verdict = "NOT_ENOUGH_TRUST"
/\ history[s2].verdict = "NOT_ENOUGH_TRUST"
ThreeNotEnoughTrust ==
\E s1, s2, s3 \in DOMAIN history :
/\ s1 /= s2 /\ s2 /= s3 /\ s1 /= s3
/\ history[s1].verdict = "NOT_ENOUGH_TRUST"
/\ history[s2].verdict = "NOT_ENOUGH_TRUST"
/\ history[s3].verdict = "NOT_ENOUGH_TRUST"
\* Test an execution that finishes with success, and processes two headers with insufficient trust on the way
Test2NotEnoughTrustSuccess ==
/\ state = "finishedSuccess"
/\ TwoNotEnoughTrust
\* Test an execution that finishes with failure, and processes two headers with insufficient trust on the way
Test2NotEnoughTrustFailure ==
/\ state = "finishedFailure"
/\ TwoNotEnoughTrust
\* Test an execution that finishes with success, and processes three headers with insufficient trust on the way
Test3NotEnoughTrustSuccess ==
/\ state = "finishedSuccess"
/\ ThreeNotEnoughTrust
\* Test an execution that finishes with failure, and processes three headers with insufficient trust on the way
Test3NotEnoughTrustFailure ==
/\ state = "finishedFailure"
/\ ThreeNotEnoughTrust
TestNonMonotonicHeight ==
/\ \E s \in DOMAIN history :
\* this is wrong
/\ history[s].current.header.height <= history[s].verified.header.height
\* everything else is correct
/\ history[s].current.header /= history[s].verified.header
/\ history[s].current.header.time > history[s].verified.header.time
/\ history[s].current.header.time < history[s].now
/\ history[s].verified.header.time + TRUSTING_PERIOD > history[s].now
/\ history[s].current.Commits /= {}
/\ history[s].current.Commits \subseteq history[s].current.header.VS
(*
Following three tests have been disabled for now,
please refer issue: https://github.com/informalsystems/tendermint-rs/issues/659
TestEmptyCommitEmptyValset ==
/\ \E s \in DOMAIN history :
\* this is wrong
/\ history[s].current.Commits = {}
/\ ValSet(s) = {}
\* everything else is correct
/\ history[s].current.header /= history[s].verified.header
/\ history[s].current.header.height > history[s].verified.header.height
/\ history[s].current.header.time > history[s].verified.header.time
/\ history[s].current.header.time < history[s].now
/\ history[s].verified.header.time + TRUSTING_PERIOD > history[s].now
TestEmptyCommitNonEmptyValset ==
/\ \E s \in DOMAIN history :
\* this is wrong
/\ history[s].current.Commits = {}
/\ ValSet(s) /= {}
\* everything else is correct
/\ history[s].current.header /= history[s].verified.header
/\ history[s].current.header.height > history[s].verified.header.height
/\ history[s].current.header.time > history[s].verified.header.time
/\ history[s].current.header.time < history[s].now
/\ history[s].verified.header.time + TRUSTING_PERIOD > history[s].now
TestLessThanTwoThirdsCommit ==
/\ \E s \in DOMAIN history :
\* this is wrong
LET CMS == history[s].current.Commits
UVS == history[s].current.header.VS
TVS == history[s].verified.header.VS
IN
/\ history[s].current.header.height > history[s].verified.header.height + 1
/\ CMS /= {}
/\ CMS \subseteq UVS
/\ 3 * Cardinality(CMS) < 2 * Cardinality(UVS)
/\ 3 * Cardinality(CMS \intersect TVS) < Cardinality(TVS)
\* everything else is correct
/\ history[s].current.header /= history[s].verified.header
/\ history[s].current.header.height > history[s].verified.header.height
/\ history[s].current.header.time > history[s].verified.header.time
/\ history[s].current.header.time < history[s].now
/\ history[s].verified.header.time + TRUSTING_PERIOD > history[s].now
*)
\* Time-related tests
\* Test an execution where a header is received from the future
TestHeaderFromFuture ==
/\ \E s \in DOMAIN history :
/\ history[s].now < history[s].current.header.time
/\ history[s].now < history[s].verified.header.time + TRUSTING_PERIOD
\* Test an execution where the untrusted header time is before the trusted header time
TestUntrustedBeforeTrusted ==
/\ \E s \in DOMAIN history :
LET CMS == history[s].current.Commits
UVS == history[s].current.header.VS
IN
/\ history[s].current.header.time < history[s].verified.header.time
/\ history[s].now < history[s].verified.header.time + TRUSTING_PERIOD
/\ CMS /= {}
/\ UVS /= {}
/\ Cardinality(CMS) < Cardinality(UVS)
\* Test an execution where a header is outside the trusting period
TestHeaderNotWithinTrustingPeriod ==
/\ Cardinality(DOMAIN fetchedLightBlocks) = TARGET_HEIGHT
/\ \E s \in DOMAIN history :
/\ history[s].now > history[s].verified.header.time + TRUSTING_PERIOD
/\ history[s].current.header.time < history[s].now
\* Validator set tests
\* Test an execution where the validator sets differ at each step
TestValsetDifferentAllSteps ==
/\ Cardinality(DOMAIN fetchedLightBlocks) = TARGET_HEIGHT
/\ \A s1, s2 \in DOMAIN history :
s1 /= s2 =>
history[s1].current.header.VS /= history[s2].current.header.VS
TestHalfValsetChanges ==
/\ Cardinality(DOMAIN fetchedLightBlocks) = TARGET_HEIGHT
/\ \E s1, s2 \in DOMAIN history :
/\ s2 = s1 + 1
/\ Cardinality(ValSet(s1)) >= 3
/\ 2 * Cardinality(ValSet(s1) \intersect ValSet(s2)) < Cardinality(ValSet(s1))
TestHalfValsetChangesVerdictSuccess ==
/\ Cardinality(DOMAIN fetchedLightBlocks) = TARGET_HEIGHT
/\ \E s1, s2 \in DOMAIN history :
/\ s2 = s1 + 1
/\ history[s2].verdict = "SUCCESS"
/\ Cardinality(ValSet(s1)) >= 3
/\ 2 * Cardinality(ValSet(s1) \intersect ValSet(s2)) < Cardinality(ValSet(s1))
TestHalfValsetChangesVerdictNotEnoughTrust ==
/\ Cardinality(DOMAIN fetchedLightBlocks) = TARGET_HEIGHT
/\ \E s1, s2 \in DOMAIN history :
/\ s2 = s1 + 1
/\ history[s2].verdict = "NOT_ENOUGH_TRUST"
/\ Cardinality(ValSet(s1)) >= 3
/\ 2 * Cardinality(ValSet(s1) \intersect ValSet(s2)) < Cardinality(ValSet(s1))
TestValsetDoubles ==
/\ Cardinality(DOMAIN fetchedLightBlocks) = TARGET_HEIGHT
/\ \E s1, s2 \in DOMAIN history :
/\ s2 = s1 + 1
/\ Cardinality(ValSet(s1)) >= 2
/\ Cardinality(ValSet(s2)) = 2 * Cardinality(ValSet(s1))
TestValsetHalves ==
/\ Cardinality(DOMAIN fetchedLightBlocks) = TARGET_HEIGHT
/\ \E s1, s2 \in DOMAIN history :
/\ s2 = s1 + 1
/\ Cardinality(ValSet(s1)) >= 4
/\ Cardinality(ValSet(s1)) = 2 * Cardinality(ValSet(s2))
TestValsetChangesFully ==
/\ Cardinality(DOMAIN fetchedLightBlocks) = TARGET_HEIGHT
/\ \E s1, s2 \in DOMAIN history :
/\ s2 = s1 + 1
/\ Cardinality(ValSet(s1)) >= 2
/\ ValSet(s1) \intersect ValSet(s2) = {}
TestLessThanThirdValsetChanges ==
/\ Cardinality(DOMAIN fetchedLightBlocks) = TARGET_HEIGHT
/\ \E s1, s2 \in DOMAIN history :
/\ s2 = s1 + 1
/\ Cardinality(ValSet(s1)) >= 4
/\ ValSet(s2) /= ValSet(s1)
/\ 3 * Cardinality(ValSet(s2) \ ValSet(s1)) < Cardinality(ValSet(s1))
TestMoreThanTwoThirdsValsetChanges ==
/\ Cardinality(DOMAIN fetchedLightBlocks) = TARGET_HEIGHT
/\ \E s1, s2 \in DOMAIN history :
/\ s2 = s1 + 1
/\ Cardinality(ValSet(s1)) >= 4
/\ 3 * Cardinality(ValSet(s2) \ ValSet(s1)) > 2 * Cardinality(ValSet(s1))
TestOneThirdValsetChanges ==
/\ Cardinality(DOMAIN fetchedLightBlocks) = TARGET_HEIGHT
/\ \E s1, s2 \in DOMAIN history :
/\ s2 = s1 + 1
/\ Cardinality(ValSet(s1)) >= 3
/\ 3 * Cardinality(ValSet(s2) \ ValSet(s1)) = Cardinality(ValSet(s1))
TestTwoThirdsValsetChanges ==
/\ Cardinality(DOMAIN fetchedLightBlocks) = TARGET_HEIGHT
/\ \E s1, s2 \in DOMAIN history :
/\ s2 = s1 + 1
/\ Cardinality(ValSet(s1)) >= 3
/\ 3 * Cardinality(ValSet(s2) \ ValSet(s1)) = 2 * Cardinality(ValSet(s1))
TestLessThanTwoThirdsSign ==
/\ Cardinality(DOMAIN fetchedLightBlocks) = TARGET_HEIGHT
/\ \E s \in DOMAIN history :
/\ history[s].verified.header.time + TRUSTING_PERIOD > history[s].now
\* this is wrong
/\ \E commits \in SUBSET AllNodes:
\E block \in BC!LightBlocks:
/\ 3 * Cardinality(commits) < 2 * Cardinality(ValSet(s))
/\ CopyLightBlockFromChain(block, Height(s))
/\ LightBlock(s) = [ block EXCEPT !.Commits = commits]
TestMoreThanTwoThirdsSign ==
/\ Cardinality(DOMAIN fetchedLightBlocks) = TARGET_HEIGHT
/\ \E s \in DOMAIN history :
3 * Cardinality(ValCommits(s)) >= 2 * Cardinality(ValSet(s))
============================================================================
\* When Apalache is fixed to work with operator params, we should rewrite the validator set tests as shown below
\* A configurable test for two neighbor valsets
TestNeighborValsets(test(_,_)) ==
/\ Cardinality(DOMAIN fetchedLightBlocks) = TARGET_HEIGHT
/\ \E s1, s2 \in DOMAIN history :
/\ s2 = s1 + 1
/\ test(ValSet(s1), ValSet(s2))
\* A configurable test for two neighbor valsets and expected verdict
TestNeighborValsetsVerdict(test(_,_), want_verdict) ==
/\ Cardinality(DOMAIN fetchedLightBlocks) = TARGET_HEIGHT
/\ \E s1, s2 \in DOMAIN history :
/\ s2 = s1 + 1
/\ test(ValSet(s1), ValSet(s2))
/\ history[s2].verdict = want_verdict
HalfValsetChanges(vs1, vs2) ==
/\ Cardinality(vs1) >= 3
/\ 2 * Cardinality(vs1 \intersect vs2) < Cardinality(vs1)
TestHalfValsetChanges == TestNeighborValsets(HalfValsetChanges)
TestHalfValsetChangesVerdictSuccess == TestNeighborValsetsVerdict(HalfValsetChanges, "SUCCESS")
TestHalfValsetChangesVerdictNotEnoughTrust == TestNeighborValsetsVerdict(HalfValsetChanges, "NOT_ENOUGH_TRUST")
ValsetDoubles(vs1, vs2) ==
/\ Cardinality(vs1) >= 2
/\ Cardinality(vs2) = 2 * Cardinality(vs1)
TestValsetDoubles == TestNeighborValsets(ValsetDoubles)
TestValsetDoublesVerdictSuccess == TestNeighborValsetsVerdict(ValsetDoubles, "SUCCESS")
TestValsetDoublesVerdictNotEnoughTrust == TestNeighborValsetsVerdict(ValsetDoubles, "NOT_ENOUGH_TRUST")