btest/plugin: Add plugin testing enum identifiers

This plugin has a generic name, but for now just tests the API around
enum types and enum vals at InitPostScript() time.

testing/btest/Baseline/plugins.api-plugin/output

@@ -0,0 +1,2 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+TestEnumIdentifiers successful

testing/btest/plugins/api-plugin.zeek

@@ -0,0 +1,26 @@
+# @TEST-DOC: A plugin testing some parts Zeek's C++ API
+# @TEST-EXEC: ${DIST}/auxil/zeek-aux/plugin-support/init-plugin -u . Demo API
+# @TEST-EXEC: cp -r %DIR/api-plugin/* .
+#
+# @TEST-EXEC: ./configure --zeek-dist=${DIST} && make
+#
+# @TEST-EXEC: ZEEK_PLUGIN_PATH=`pwd` zeek %INPUT >output
+#
+# @TEST-EXEC: TEST_DIFF_CANONIFIER= btest-diff output
+
+module DemoAPI;
+
+export {
+	type Severity: enum {
+		CRITICAL = 1,
+		ERROR = 2,
+		WARNING = 3,
+		INFO = 4,
+	};
+}
+
+module User;
+
+redef enum DemoAPI::Severity += {
+	USER_DEBUG = 50,
+};

testing/btest/plugins/api-plugin/src/Plugin.cc

@@ -0,0 +1,88 @@
+
+#include "Plugin.h"
+
+#include <zeek/ID.h>
+#include <zeek/Reporter.h>
+#include <zeek/Type.h>
+#include <zeek/Val.h>
+#include <iostream>
+
+namespace btest::plugin::Demo_API {
+Plugin plugin;
+}
+
+using namespace btest::plugin::Demo_API;
+
+zeek::plugin::Configuration Plugin::Configure() {
+    zeek::plugin::Configuration config;
+    config.name = "Demo::API";
+    config.description = "Use some of Zeek's API for testing";
+    config.version.major = 1;
+    config.version.minor = 0;
+    config.version.patch = 0;
+    return config;
+}
+
+namespace {
+
+// Test zeek::id::find for enums an their types.
+void TestEnumIdentifiers() {
+    auto severity_type = zeek::id::find_type<zeek::EnumType>("DemoAPI::Severity");
+    if ( ! severity_type )
+        zeek::reporter->FatalError("DemoAPI::Severity not found");
+
+    // Expect 5 entries!
+    if ( severity_type->Names().size() != 5 )
+        zeek::reporter->FatalError("Wrong number of severities %" PRId64, severity_type->Names().size());
+
+    // Ensure CRITICAL and USER_DEBUG identifiers have the same enum type as severity_type.
+    auto critical_id = zeek::id::find("DemoAPI::CRITICAL");
+    auto critical_type = critical_id->GetType();
+    auto user_debug_id = zeek::id::find("User::USER_DEBUG");
+    auto user_debug_type = user_debug_id->GetType();
+
+    if ( critical_type != user_debug_type )
+        zeek::reporter->FatalError("CRITICAL and USER_DEBUG have different types (%p and %p)", critical_type.get(),
+                                   user_debug_type.get());
+
+    // Ensure the critical_id and user_debug_type IDs have an EnumVal attached
+    // and that the value is the same as in script land.
+    auto critical_val = critical_id->GetVal();
+    auto user_debug_val = user_debug_id->GetVal();
+
+    if ( ! critical_val || ! user_debug_val )
+        zeek::reporter->FatalError("Missing values on enum value identifiers %p %p", critical_val.get(),
+                                   user_debug_val.get());
+
+    if ( critical_val->AsEnum() != 1 )
+        zeek::reporter->FatalError("Wrong value for CRITICAL: %" PRId64, critical_val->AsEnum());
+
+    if ( user_debug_val->AsEnum() != 50 )
+        zeek::reporter->FatalError("Wrong value for USER_DEBUG: %" PRId64, user_debug_val->AsEnum());
+
+    // Ensure all the types (identifiers and values) agree with severity_type.
+    if ( critical_type != severity_type )
+        zeek::reporter->FatalError("CRITICAL identifier has the wrong enum type %p vs %p", critical_type.get(),
+                                   severity_type.get());
+
+    if ( user_debug_type != severity_type )
+        zeek::reporter->FatalError("USER_DEBUG identifier has the wrong enum type %p vs %p", user_debug_type.get(),
+                                   severity_type.get());
+
+    if ( critical_val->GetType() != severity_type )
+        zeek::reporter->FatalError("CRITICAL value has the wrong enum type %p vs %p", critical_val->GetType().get(),
+                                   severity_type.get());
+
+    if ( user_debug_val->GetType() != severity_type )
+        zeek::reporter->FatalError("USER_DEBUG value has the wrong enum type %p vs %p", user_debug_val->GetType().get(),
+                                   severity_type.get());
+
+    std::cout << "TestEnumIdentifiers successful" << std::endl;
+}
+
+} // namespace
+
+void Plugin::InitPostScript() {
+    // Other API tests if wanted.
+    TestEnumIdentifiers();
+}

testing/btest/plugins/api-plugin/src/Plugin.h

@@ -0,0 +1,18 @@
+
+#pragma once
+
+#include <zeek/plugin/Plugin.h>
+
+namespace btest::plugin::Demo_API {
+
+class Plugin : public zeek::plugin::Plugin {
+protected:
+    // Overridden from zeek::plugin::Plugin.
+    zeek::plugin::Configuration Configure() override;
+
+    void InitPostScript() override;
+};
+
+extern Plugin plugin;
+
+} // namespace btest::plugin::Demo_API