Add concurrency tests

test/test05_payments_ldknode_concurrency.bats

@@ -0,0 +1,61 @@
+#!/usr/bin/env bats
+
+# set -eo pipefail
+# set -x
+
+setup() {
+    load 'test_helper/common-setup'
+    _common_setup
+
+    source "$PROJECT_ROOT/test/functions.sh"
+
+    TEST_COUNT=10
+    SUCCESS_COUNT=0
+}
+
+increment_success_count() {
+    (( ++SUCCESS_COUNT ))
+}
+
+print_success_count() {
+    echo "$SUCCESS_COUNT"
+}
+
+get_offer() {
+    OFFER=$(generate_offer_ldknode 'ldknode2')
+}
+
+print_offer() {
+    echo "$OFFER"
+}
+
+attempt() {
+    local result
+    result=$($PROJECT_ROOT/bin/lndk-cli lndk1 pay-offer "$OFFER" 5000000)
+    if [[ "$result" =~ "Successfully paid for offer!" ]]; then
+        echo "success" >> "$BATS_TMPDIR/success_count"
+    fi
+}
+
+increment_success_count() {
+    SUCCESS_COUNT=$(wc -l < "$BATS_TMPDIR/success_count")
+}
+
+@test "Concurrent payments to LDK Node (lnd1 -> lnd2 -> ldknode2) x 10" {
+    mkdir -p "$BATS_TMPDIR"
+    : > "$BATS_TMPDIR/success_count" # Reset file for counting successes
+
+    get_offer
+    run print_offer
+
+    for i in $(seq 1 $TEST_COUNT); do
+        attempt &
+    done
+
+    wait # Wait for all background jobs to finish
+
+    increment_success_count
+
+    run print_success_count
+    assert_equal "$SUCCESS_COUNT" "$TEST_COUNT"
+}