feat: add watcher test (ported from Go's watcher_test.go) (casbin#386)

Author: CoolLoong

src/test/java/org/casbin/jcasbin/main/WatcherTest.java

@@ -0,0 +1,83 @@
+// Copyright 2024 The casbin Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package org.casbin.jcasbin.main;
+
+import org.casbin.jcasbin.persist.Watcher;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.function.Consumer;
+
+import static org.junit.Assert.fail;
+
+public class WatcherTest {
+    public static class SampleWatcher implements Watcher {
+        Consumer<String> callback;
+
+        @Override
+        public void setUpdateCallback(Runnable runnable) {
+            callback = (s) -> {
+                runnable.run();
+            };
+        }
+
+        @Override
+        public void setUpdateCallback(Consumer<String> func) {
+            callback = func;
+        }
+
+        @Override
+        public void update() {
+            if (callback != null) {
+                callback.accept("");
+            }
+        }
+    }
+
+
+    @Test
+    public void testSetWatcher() {
+        Enforcer enforcer = new Enforcer("examples/rbac_model.conf", "examples/rbac_policy.csv");
+        AtomicBoolean status = new AtomicBoolean(false);
+        SampleWatcher thisIsTestWatcher = new SampleWatcher();
+        enforcer.setWatcher(thisIsTestWatcher);
+        enforcer.watcher.setUpdateCallback((s) -> {
+            status.set(true);
+        });
+        enforcer.savePolicy();//calls watcher.Update()
+        Assert.assertTrue(status.get());
+    }
+
+    @Test
+    public void testSelfModify() {
+        Enforcer enforcer = new Enforcer("examples/rbac_model.conf", "examples/rbac_policy.csv");
+        SampleWatcher thisIsTestWatcher = new SampleWatcher();
+        enforcer.setWatcher(thisIsTestWatcher);
+        AtomicInteger called = new AtomicInteger(-1);
+        enforcer.watcher.setUpdateCallback((s) -> {
+            called.set(1);
+        });
+        boolean r = enforcer.addPolicy("eva", "data", "read");//calls watcher.Update()
+        if (!r) {
+            fail("addPolicy error");
+        }
+        if (called.get() != 1) {
+            fail("callback should be called");
+        }
+        //todo SelfAddPolicy
+    }
+}