Add test for xcodeproj without Package.resolved

.buildkite/pipeline.yml

@@ -29,6 +29,9 @@ steps:
       - label: ":xcode: Xcode Project - Explicit"
         command: tests/install_swiftpm_dependencies/test_scripts/test_project_explicit.sh
 
+      - label: ":xcode: Xcode Project - No Package.resolved"
+        command: tests/install_swiftpm_dependencies/test_scripts/test_project_no_package.sh
+
       - label: ":xcode: Xcode Workspace - Autodetect"
         command: tests/install_swiftpm_dependencies/test_scripts/test_workspace_automatic.sh
 

tests/install_swiftpm_dependencies/test_scripts/test_project_no_package.sh

@@ -0,0 +1,37 @@
+#!/bin/bash -eu
+
+set -o pipefail
+
+source "$(dirname "${BASH_SOURCE[0]}")/set_up_environment.sh"
+
+echo "--- :computer: Jump to test folder"
+pushd "$TESTS_LOCATION/../project"
+
+echo "--- :computer: Generate project"
+brew install xcodegen
+make
+
+# Notice we do not set up the fixture Package.resolved.
+# As such, we expect the call to the plugin to fail.
+
+echo "--- :wrench: Run install_swiftpm_dependencies"
+PROJECT=Demo.xcodeproj
+LOGS_PATH=logs
+set +e
+install_swiftpm_dependencies --project $PROJECT 2>&1 | tee "$LOGS_PATH"
+CMD_EXIT_STATUS=$?
+set -e
+
+if [[ $CMD_EXIT_STATUS -eq 0 ]]; then
+  echo "^^^ install_swiftpm_dependencies unexpectedly succeeded without a Package.resolved in the project folder!"
+  exit 1
+else
+  EXPECTED="Unable to find \`Package.resolved\` file ($PROJECT/project.xcworkspace/xcshareddata/swiftpm/Package.resolved)"
+  if grep -qF "$EXPECTED" "$LOGS_PATH"; then
+    echo "^^^ +++ install_swiftpm_dependencies failed as expected because there is no Package.resolved in the project folder."
+  else
+    echo "+++ install_swiftpm_dependencies failed, but the message it printed is not what we expected."
+    echo "Expected: $EXPECTED"
+    echo "Got: $(cat $LOGS_PATH)"
+  fi
+fi