test/e2e/double_singing: wait for first block

.changelog/unreleased/bug-fixes/1246-fix-pos-slashing.md

@@ -0,0 +1,3 @@
+- PoS: Fixed an issue with slashable evidence processed
+  and applied at a new epoch causing a ledger to crash.
+  ([#1246](https://github.com/anoma/namada/pull/1246))

apps/src/lib/node/ledger/shell/finalize_block.rs

@@ -73,6 +73,10 @@ where
             )?;
         }
 
+        // Invariant: This has to be applied after
+        // `copy_validator_sets_and_positions` if we're starting a new epoch
+        self.slash();
+
         let wrapper_fees = self.get_wrapper_tx_fees();
         let mut stats = InternalStats::default();
 
@@ -404,8 +408,6 @@ where
             .wl_storage
             .update_epoch(height, header_time)
             .expect("Must be able to update epoch");
-
-        self.slash();
         (height, new_epoch)
     }
 

scripts/repeat-e2e-test.sh

@@ -0,0 +1,29 @@
+#!/bin/sh
+# Run an e2e test at most n times, exit at first failure.
+# This can be handy for testing of non-deterministic issues that are tricky to
+# reproduce.
+#
+# The first arg is the max number of repetitions and second is the exact name 
+# of the test.
+#
+# Usage example:
+# $ scripts/repeat-e2e-test.sh 10 e2e::ledger_tests::run_ledger
+#
+# Adapted from https://gitlab.com/tezos/tezos/-/blob/master/tests_python/scripts/repeat_test.sh
+
+NUM=$1
+TEST=$2
+# Thanks internet https://stackoverflow.com/a/4774063/3210255
+SCRIPTPATH="$( cd -- "$(dirname "$0")" >/dev/null 2>&1 ; pwd -P )"
+NIGHTLY=$(cat "$SCRIPTPATH"/../rust-nightly-version)
+
+for i in $(seq 1 "$NUM")
+do
+    echo "Execution $i/$NUM"
+    if ! RUST_BACKTRACE=1 NAMADA_E2E_KEEP_TEMP=true NAMADA_E2E_DEBUG=true cargo "+$NIGHTLY" test "$TEST" -Z unstable-options -- --exact --test-threads=1 --nocapture; then
+        exit 1
+    fi
+done
+exit 0
+
+

tests/src/e2e/ledger_tests.rs

@@ -3211,11 +3211,15 @@ fn double_signing_gets_slashed() -> Result<()> {
         run_as!(test, Who::Validator(0), Bin::Node, args, Some(40))?;
     validator_0.exp_string("Namada ledger node started")?;
     validator_0.exp_string("This node is a validator")?;
-    let _bg_validator_0 = validator_0.background();
     let mut validator_1 =
         run_as!(test, Who::Validator(1), Bin::Node, args, Some(40))?;
     validator_1.exp_string("Namada ledger node started")?;
     validator_1.exp_string("This node is a validator")?;
+
+    // Wait for a first block
+    validator_0.exp_string("Committed block hash")?;
+
+    let _bg_validator_0 = validator_0.background();
     let bg_validator_1 = validator_1.background();
 
     // 2. Copy the first genesis validator base-dir