Enable create_script_context in CI

.github/regression.sh

@@ -23,11 +23,35 @@ mkdir -p "$WORKDIR"
 export TMPDIR="$WORKDIR/tmp"
 mkdir -p "$TMPDIR"
 
-if [ "${CI_ENABLE_DBSYNC:-"false"}" != "false" ]; then
-  # setup dbsync
-  # shellcheck disable=SC1090,SC1091
-  . .github/source_dbsync.sh
-fi
+# setup dbsync (disabled by default)
+case "${CI_ENABLE_DBSYNC:-"false"}" in
+  "true" | 1)
+    # shellcheck disable=SC1090,SC1091
+    . .github/source_dbsync.sh
+    ;;
+  "false" | 0)
+    ;;
+  *)
+    echo "Unknown value for CI_ENABLE_DBSYNC: ${CI_ENABLE_DBSYNC}" >&2
+    exit 1
+    ;;
+esac
+
+# setup plutus-apps (enabled by default)
+# The "plutus-apps" repo is needed for the `create-script-context` tool, which is used by the
+# Plutus tests that are testing script context.
+case "${CI_ENABLE_PLUTUS_APPS:-"true"}" in
+  "true" | 1)
+    # shellcheck disable=SC1090,SC1091
+    . .github/source_plutus_apps.sh
+    ;;
+  "false" | 0)
+    ;;
+  *)
+    echo "Unknown value for CI_ENABLE_PLUTUS: ${CI_ENABLE_PLUTUS}" >&2
+    exit 1
+    ;;
+esac
 
 if [ "${CI_TOPOLOGY:-""}" = "p2p" ]; then
   export ENABLE_P2P="true"

.github/source_plutus_apps.sh

@@ -0,0 +1,25 @@
+#!/bin/bash
+
+echo "::group::plutus-apps setup"
+
+pushd "$WORKDIR" || exit 1
+
+# Clone plutus-apps if needed
+if [ ! -e plutus-apps ]; then
+  git clone --depth 1 --recurse-submodules --shallow-submodules https://github.com/input-output-hk/plutus-apps.git
+fi
+
+pushd plutus-apps || exit 1
+git pull origin main
+git rev-parse HEAD
+
+# Build `create-script-context`
+nix build --accept-flake-config .#create-script-context -o create-script-context
+
+# Add `create-script-context` to PATH
+PATH="$(readlink -m create-script-context/bin)":"$PATH"
+export PATH
+
+pushd "$REPODIR" || exit 1
+
+echo "::endgroup::"