Add tests attempting to load shipped rulesets

It's bad when they don't read, and we may not notice for a while.
See longturn#380 (not a real autogames but a good starting point) and longturn#868.

cmake/FreecivDependencies.cmake

@@ -164,3 +164,9 @@ endif()
 if (FREECIV_ENABLE_FCMP_CLI OR FREECIV_ENABLE_FCMP_QT)
   find_package(SQLite3 REQUIRED)
 endif()
+
+# Testing
+include(CTest)
+if (BUILD_TESTING)
+  find_package(Qt5Test REQUIRED)
+endif()

data/CMakeLists.txt

@@ -1,3 +1,5 @@
+set(RULESET_LIST)
+
 function(add_ruleset)
   cmake_parse_arguments(ARG "SERV_FILE" "NAME;README" "" ${ARGN})
   if (ARG_SERV_FILE)
@@ -12,6 +14,8 @@ function(add_ruleset)
       DESTINATION "${CMAKE_INSTALL_DATADIR}/${PROJECT_NAME}/${ARG_NAME}"
       COMPONENT freeciv21)
   endif()
+  list(APPEND RULESET_LIST ${ARG_NAME})
+  set(RULESET_LIST "${RULESET_LIST}" PARENT_SCOPE)
   install(
     FILES
     ${ARG_NAME}/buildings.ruleset
@@ -75,6 +79,13 @@ if (FREECIV_ENABLE_SERVER OR FREECIV_ENABLE_RULEDIT)
     FILES override/nation.ruleset
     DESTINATION "${CMAKE_INSTALL_DATADIR}/${PROJECT_NAME}/override"
     COMPONENT freeciv21)
+
+  # Ruleset tests
+  if (BUILD_TESTING AND FREECIV_ENABLE_SERVER)
+    # The stub ruleset isn't installed, but we test it
+    list(APPEND RULESET_LIST stub)
+    add_subdirectory(tests)
+  endif()
 endif()
 
 if (FREECIV_ENABLE_SERVER)

data/tests/CMakeLists.txt

@@ -0,0 +1,19 @@
+set(CMAKE_AUTOMOC ON)
+
+enable_testing(true)
+
+# Turn the list of rulesets into something C++ will understand
+list(JOIN RULESET_LIST "\", \"" ruleset_list_cpp)
+if (NOT ${ruleset_list_cpp} STREQUAL "")
+  set(ruleset_list_cpp "\"${ruleset_list_cpp}\"")
+endif()
+
+# Create the test file. This is ugly because we need to replace variables
+# and use generator expressions.
+configure_file(rulesets.cpp.in ${CMAKE_CURRENT_BINARY_DIR}/rulesets.cpp.in)
+file(GENERATE OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/rulesets.cpp
+              INPUT ${CMAKE_CURRENT_BINARY_DIR}/rulesets.cpp.in)
+
+add_executable(test_rulesets ${CMAKE_CURRENT_BINARY_DIR}/rulesets.cpp)
+add_test(NAME test_rulesets COMMAND test_rulesets)
+target_link_libraries(test_rulesets PRIVATE Qt5::Test)

data/tests/rulesets.cpp.in

@@ -0,0 +1,60 @@
+#include <QProcess>
+
+#include <QtTest>
+
+// Macro values replaced by cmake
+#define RULESETS "$<JOIN:${RULESET_LIST},", ">"
+#define SERVER_PATH "$<TARGET_FILE:freeciv21-server>"
+
+/**
+ * Ruleset-related tests
+ */
+class test_rulesets : public QObject {
+  Q_OBJECT
+
+private slots:
+  void load_data();
+  void load();
+};
+
+/**
+ * Generates test data for load()
+ */
+void test_rulesets::load_data()
+{
+  QTest::addColumn<QString>("name");
+  QTest::addColumn<bool>("exists");
+
+  const char *names[] = {"default", RULESETS};
+  for (auto &name : names) {
+    QTest::newRow(name) << name << true;
+  }
+
+  // A ruleset that doesn't exist
+  QTest::newRow("error") << "error" << false;
+}
+
+/**
+ * Tries to spawn a server with a ruleset.
+ */
+void test_rulesets::load()
+{
+  QFETCH(QString, name);
+  QFETCH(bool, exists);
+
+  QProcess p;
+  p.start(SERVER_PATH, {QStringLiteral("-r"), name});
+  p.waitForStarted();
+  p.write("quit\n");
+  p.closeWriteChannel();
+  p.waitForFinished(5000);
+
+  if (exists) {
+    QCOMPARE(p.exitCode(), 0);
+  } else {
+    QCOMPARE(p.exitCode(), 1);
+  }
+}
+
+QTEST_MAIN(test_rulesets)
+#include "rulesets.moc"