add unit test for GlobalRequestLimiter

Signed-off-by: yunfeiyanggzq <yunfeiyang@buaa.edu.cn>

sentinel-cluster/sentinel-cluster-server-default/src/test/java/com/alibaba/csp/sentinel/cluster/flow/statistic/limit/GlobalRequestLimiterTest.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * 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 com.alibaba.csp.sentinel.cluster.flow.statistic.limit;
+
+import com.alibaba.csp.sentinel.cluster.server.config.ClusterServerConfigManager;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class GlobalRequestLimiterTest {
+    @Test
+    public void testPass() throws InterruptedException {
+        ClusterServerConfigManager.setMaxAllowedQps(3);
+        GlobalRequestLimiter.initIfAbsent("user");
+        Assert.assertNotNull(GlobalRequestLimiter.getRequestLimiter("user"));
+        Assert.assertEquals(3, GlobalRequestLimiter.getMaxAllowedQps("user"), 0.01);
+        Assert.assertTrue(GlobalRequestLimiter.tryPass("user"));
+        Assert.assertTrue(GlobalRequestLimiter.tryPass("user"));
+        Assert.assertTrue(GlobalRequestLimiter.tryPass("user"));
+        Assert.assertFalse(GlobalRequestLimiter.tryPass("user"));
+        Assert.assertEquals(3, GlobalRequestLimiter.getCurrentQps("user"), 0.01);
+        Thread.sleep(2000);
+        Assert.assertTrue(GlobalRequestLimiter.tryPass("user"));
+        Assert.assertTrue(GlobalRequestLimiter.tryPass("user"));
+        Assert.assertEquals(2, GlobalRequestLimiter.getCurrentQps("user"), 0.01);
+        GlobalRequestLimiter.applyMaxQpsChange(10);
+        Assert.assertEquals(10, GlobalRequestLimiter.getMaxAllowedQps("user"), 0.01);
+    }
+}