Add tests for error handling

fastify · May 6, 2024 · 6c86f95 · 6c86f95
1 parent b8cbd33
commit 6c86f95
Showing 1 changed file with 202 additions and 15 deletions.
diff --git a/test/encapsulated-error-handler.test.js b/test/encapsulated-error-handler.test.js
@@ -3,25 +3,66 @@
 const { test } = require('tap')
 const Fastify = require('..')
 
-test('encapsulates an error handler', async t => {
-  t.plan(3)
+// Because of how error handlers wrap things, following the control flow can be tricky
+// In this test file numbered comments indicate the order statements are expected to execute
+
+test('encapsulates an asynchronous error handler', async t => {
+  t.plan(4)
 
   const fastify = Fastify()
   fastify.register(async function (fastify) {
     fastify.setErrorHandler(async function a (err) {
-      t.equal(err.message, 'kaboom')
-      throw new Error('caught')
+      // 3. the inner error handler catches the error, and throws a new error
+      t.equal(err.message, 'from_endpoint')
+      throw new Error('from_inner')
+    })
+    fastify.get('/encapsulated', async () => {
+      // 2. the endpoint throws an error
+      throw new Error('from_endpoint')
+    })
+  })
+
+  fastify.setErrorHandler(async function b (err) {
+    // 4. the outer error handler catches the error thrown by the inner error handler
+    t.equal(err.message, 'from_inner')
+    // 5. the outer error handler throws a new error
+    throw new Error('from_outer')
+  })
+
+  // 1. the endpoint is called
+  const res = await fastify.inject('/encapsulated')
+  // 6. the default error handler returns the error from the outer error handler
+  t.equal(res.json().message, 'from_outer')
+})
+
+// See discussion in https://github.com/fastify/fastify/pull/5222#discussion_r1432573655
+test('encapsulates a synchronous error handler', async t => {
+  t.plan(4)
+
+  const fastify = Fastify()
+  fastify.register(async function (fastify) {
+    fastify.setErrorHandler(function a (err) {
+      // 3. the inner error handler catches the error, and throws a new error
+      t.equal(err.message, 'from_endpoint')
+      throw new Error('from_inner')
+    })
+    fastify.get('/encapsulated', async () => {
+      // 2. the endpoint throws an error
+      throw new Error('from_endpoint')
     })
-    fastify.get('/encapsulated', async () => { throw new Error('kaboom') })
   })
 
   fastify.setErrorHandler(async function b (err) {
-    t.equal(err.message, 'caught')
-    throw new Error('wrapped')
+    // 4. the outer error handler catches the error thrown by the inner error handler
+    t.equal(err.message, 'from_inner')
+    // 5. the outer error handler throws a new error
+    throw new Error('from_outer')
   })
 
+  // 1. the endpoint is called
   const res = await fastify.inject('/encapsulated')
-  t.equal(res.json().message, 'wrapped')
+  // 6. the default error handler returns the error from the outer error handler
+  t.equal(res.json().message, 'from_outer')
 })
 
 test('onError hook nested', async t => {
@@ -30,21 +71,167 @@ test('onError hook nested', async t => {
   const fastify = Fastify()
   fastify.register(async function (fastify) {
     fastify.setErrorHandler(async function a (err) {
-      t.equal(err.message, 'kaboom')
-      throw new Error('caught')
+      // 4. the inner error handler catches the error, and throws a new error
+      t.equal(err.message, 'from_endpoint')
+      throw new Error('from_inner')
+    })
+    fastify.get('/encapsulated', async () => {
+      // 2. the endpoint throws an error
+      throw new Error('from_endpoint')
     })
-    fastify.get('/encapsulated', async () => { throw new Error('kaboom') })
   })
 
   fastify.setErrorHandler(async function b (err) {
-    t.equal(err.message, 'caught')
-    throw new Error('wrapped')
+    // 5. the outer error handler catches the error thrown by the inner error handler
+    t.equal(err.message, 'from_inner')
+    // 6. the outer error handler throws a new error
+    throw new Error('from_outer')
   })
 
   fastify.addHook('onError', async function (request, reply, err) {
-    t.equal(err.message, 'kaboom')
+    // 3. the hook receives the error
+    t.equal(err.message, 'from_endpoint')
+  })
+
+  // 1. the endpoint is called
+  const res = await fastify.inject('/encapsulated')
+  // 7. the default error handler returns the error from the outer error handler
+  t.equal(res.json().message, 'from_outer')
+})
+
+// See https://github.com/fastify/fastify/issues/5220
+test('encapuslates an error handler, for errors thrown in hooks', async t => {
+  t.plan(3)
+
+  const fastify = Fastify()
+  fastify.register(async function (fastify) {
+    fastify.setErrorHandler(function a (err) {
+      // 3. the inner error handler catches the error, and throws a new error
+      t.equal(err.message, 'from_hook')
+      throw new Error('from_inner')
+    })
+    fastify.addHook('onRequest', async () => {
+      // 2. the hook throws an error
+      throw new Error('from_hook')
+    })
+    fastify.get('/encapsulated', async () => {})
   })
 
+  fastify.setErrorHandler(function b (err) {
+    // 4. the outer error handler catches the error thrown by the inner error handler
+    t.equal(err.message, 'from_inner')
+    // 5. the outer error handler throws a new error
+    throw new Error('from_outer')
+  })
+
+  // 1. the endpoint is called
+  const res = await fastify.inject('/encapsulated')
+  // 6. the default error handler returns the error from the outer error handler
+  t.equal(res.json().message, 'from_outer')
+})
+
+// See https://github.com/fastify/fastify/issues/5220
+test('encapuslates many synchronous error handlers that rethrow errors', async t => {
+  const DEPTH = 100
+  t.plan(DEPTH + 2)
+
+  /**
+   * This creates a very nested set of error handlers, that looks like:
+   * plugin
+   * - error handler
+   * - plugin
+   *   - error handler
+   *   - plugin
+   *     ... {to DEPTH levels}
+   *       - plugin
+   *           - error handler
+   *           - GET /encapsulated
+   */
+  const createNestedRoutes = (fastify, depth) => {
+    if (depth < 0) {
+      throw new Error('Expected depth >= 0')
+    } else if (depth === 0) {
+      fastify.setErrorHandler(function a (err) {
+        // 3. innermost error handler catches the error, and throws a new error
+        t.equal(err.message, 'from_route')
+        throw new Error(`from_handler_${depth}`)
+      })
+      fastify.get('/encapsulated', async () => {
+        // 2. the endpoint throws an error
+        throw new Error('from_route')
+      })
+    } else {
+      fastify.setErrorHandler(function d (err) {
+        // 4 to {DEPTH+4}. error handlers each catch errors, and then throws a new error
+        t.equal(err.message, `from_handler_${depth - 1}`)
+        throw new Error(`from_handler_${depth}`)
+      })
+
+      fastify.register(async function (fastify) {
+        createNestedRoutes(fastify, depth - 1)
+      })
+    }
+  }
+
+  const fastify = Fastify()
+  createNestedRoutes(fastify, DEPTH)
+
+  // 1. the endpoint is called
+  const res = await fastify.inject('/encapsulated')
+  // {DEPTH+5}. the default error handler returns the error from the outermost error handler
+  t.equal(res.json().message, `from_handler_${DEPTH}`)
+})
+
+// See https://github.com/fastify/fastify/issues/5220
+// This was not failing previously, but we want to make sure the behavior continues to work in the same way across async and sync handlers
+// Plus, the current setup is somewhat fragile to tweaks to wrapThenable as that's what retries (by calling res.send(err) again)
+test('encapuslates many asynchronous error handlers that rethrow errors', async t => {
+  const DEPTH = 100
+  t.plan(DEPTH + 2)
+
+  /**
+   * This creates a very nested set of error handlers, that looks like:
+   * plugin
+   * - error handler
+   * - plugin
+   *   - error handler
+   *   - plugin
+   *     ... {to DEPTH levels}
+   *       - plugin
+   *           - error handler
+   *           - GET /encapsulated
+   */
+  const createNestedRoutes = (fastify, depth) => {
+    if (depth < 0) {
+      throw new Error('Expected depth >= 0')
+    } else if (depth === 0) {
+      fastify.setErrorHandler(async function a (err) {
+        // 3. innermost error handler catches the error, and throws a new error
+        t.equal(err.message, 'from_route')
+        throw new Error(`from_handler_${depth}`)
+      })
+      fastify.get('/encapsulated', async () => {
+        // 2. the endpoint throws an error
+        throw new Error('from_route')
+      })
+    } else {
+      fastify.setErrorHandler(async function m (err) {
+        // 4 to {DEPTH+4}. error handlers each catch errors, and then throws a new error
+        t.equal(err.message, `from_handler_${depth - 1}`)
+        throw new Error(`from_handler_${depth}`)
+      })
+
+      fastify.register(async function (fastify) {
+        createNestedRoutes(fastify, depth - 1)
+      })
+    }
+  }
+
+  const fastify = Fastify()
+  createNestedRoutes(fastify, DEPTH)
+
+  // 1. the endpoint is called
   const res = await fastify.inject('/encapsulated')
-  t.equal(res.json().message, 'wrapped')
+  // {DEPTH+5}. the default error handler returns the error from the outermost error handler
+  t.equal(res.json().message, `from_handler_${DEPTH}`)
 })