Fix the NPE when deleting category

src/main/java/run/halo/app/controller/content/auth/ContentAuthenticationManager.java

@@ -59,13 +59,21 @@ public ContentAuthentication authenticate(ContentAuthenticationRequest authReque
     @EventListener(CategoryUpdatedEvent.class)
     public void categoryUpdatedListener(CategoryUpdatedEvent event) {
         Category category = event.getCategory();
-        categoryAuthentication.clearByResourceId(category.getId());
+        // updated category is null when remove event emited
+        if (category == null) {
+            category = event.getBeforeUpdated();
+        }
+        if (category != null) {
+            categoryAuthentication.clearByResourceId(category.getId());
+        }
     }
 
     @EventListener(PostUpdatedEvent.class)
     public void postUpdatedListener(PostUpdatedEvent event) {
         Post post = event.getPost();
-        postAuthentication.clearByResourceId(post.getId());
+        if (post != null) {
+            postAuthentication.clearByResourceId(post.getId());
+        }
     }
 
     private PostAuthentication authenticatePost(ContentAuthenticationRequest authRequest) {

src/test/java/run/halo/app/cache/LevelCacheStoreTest.java

@@ -25,7 +25,6 @@ public class LevelCacheStoreTest {
     @BeforeEach
     void setUp() throws IOException {
         String testDir = FileUtils.createTempDirectory().toString();
-        System.out.println(testDir);
         haloProperties.setWorkDir(testDir + FILE_SEPARATOR);
         cacheStore = new LevelCacheStore(haloProperties);
         cacheStore.init();

src/test/java/run/halo/app/service/impl/CategoryIntegrationTest.java

@@ -0,0 +1,95 @@
+package run.halo.app.service.impl;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.springframework.test.annotation.DirtiesContext.ClassMode.BEFORE_EACH_TEST_METHOD;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.jdbc.EmbeddedDatabaseConnection;
+import org.springframework.boot.test.autoconfigure.jdbc.AutoConfigureTestDatabase;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.mock.web.MockHttpServletRequest;
+import org.springframework.test.annotation.DirtiesContext;
+import org.springframework.test.context.event.RecordApplicationEvents;
+import org.springframework.web.context.request.RequestContextHolder;
+import org.springframework.web.context.request.ServletRequestAttributes;
+import run.halo.app.cache.AbstractStringCacheStore;
+import run.halo.app.controller.content.auth.CategoryAuthentication;
+import run.halo.app.exception.NotFoundException;
+import run.halo.app.model.entity.Category;
+import run.halo.app.service.CategoryService;
+
+/**
+ * @author guqing
+ * @date 2022-04-01
+ */
+@SpringBootTest
+@RecordApplicationEvents
+@DirtiesContext(classMode = BEFORE_EACH_TEST_METHOD)
+@AutoConfigureTestDatabase(connection = EmbeddedDatabaseConnection.H2)
+public class CategoryIntegrationTest {
+
+    @Autowired
+    private CategoryService categoryService;
+    @Autowired
+    private CategoryAuthentication categoryAuthentication;
+    @Autowired
+    private AbstractStringCacheStore abstractStringCacheStore;
+
+    @BeforeEach
+    public void setUp() {
+        Category category1 = new Category();
+        category1.setId(1);
+        category1.setName("category-1");
+        category1.setSlug("category-1");
+        category1.setPassword("123");
+        category1.setParentId(0);
+
+        Category category2 = new Category();
+        category2.setId(2);
+        category2.setName("category-2");
+        category2.setSlug("category-2");
+        category2.setParentId(1);
+
+        categoryService.create(category1);
+        categoryService.create(category2);
+    }
+
+    @Test
+    public void authenticationAfterRemove() {
+        Category category = categoryService.getById(1);
+
+        MockHttpServletRequest request = new MockHttpServletRequest();
+        request.setRequestedSessionId("mock_session_id");
+        RequestContextHolder.setRequestAttributes(new ServletRequestAttributes(request));
+
+        boolean authenticated = categoryAuthentication.isAuthenticated(category.getId());
+        assertThat(authenticated).isFalse();
+
+        // set authenticated flag is true for No.2 category
+        categoryAuthentication.setAuthenticated(2, true);
+        assertThat(categoryAuthentication.isAuthenticated(2)).isTrue();
+
+        // set authenticated flag is true for No.1 category
+        categoryAuthentication.setAuthenticated(category.getId(), true);
+        assertThat(categoryAuthentication.isAuthenticated(category.getId())).isTrue();
+
+        // remove category and category-post relationships
+        categoryService.removeCategoryAndPostCategoryBy(category.getId());
+        // authenticated cache flag is cleared by authentication manager
+        String authenticationCacheKey =
+            categoryAuthentication.buildCacheKey(request.getRequestedSessionId(),
+                categoryAuthentication.getPrincipal().toString(), String.valueOf(category.getId()));
+        assertThat(abstractStringCacheStore.get(authenticationCacheKey)).isEmpty();
+
+        // isAuthenticated method will be throw NotFoundException because of category has been
+        // removed.
+        assertThatThrownBy(() -> categoryAuthentication.isAuthenticated(category.getId()))
+            .isInstanceOf(NotFoundException.class);
+
+        // bug other cache flags will not be affected
+        assertThat(categoryAuthentication.isAuthenticated(2)).isTrue();
+    }
+}