Revert "fix: Updated transformer to prevent instrumenting a non-existent method on a class (#59)"

This reverts commit 661eb1a.

Author: bizob2828

lib/transformer.js

@@ -95,9 +95,8 @@ class Transformer {
       state.operator = this.#getOperator(state)
 
       esquery.traverse(ast, esquery.parse(query), (...args) => {
-        if (this.#visit(state, ...args)) {
-          injectionCount++
-        }
+        injectionCount++
+        this.#visit(state, ...args)
       })
     }
 
@@ -138,12 +137,11 @@ class Transformer {
    *
    * @param {object} state - Merged config + runtime state for this traversal.
    * @param {...unknown} args - `(node, parent, ancestry)` from esquery traverse.
-   * @returns {boolean} True if injection should be counted, false otherwise.
    */
   #visit (state, ...args) {
     const transform = this.#customTransforms[state.operator] ?? transforms[state.operator]
     const { index = 0 } = state.functionQuery
-    const [node, , ancestry] = args
+    const [node] = args
     const type = node.init?.type || node.type
 
     // Class nodes are visited for traceInstanceMethod (missing method patching),
@@ -153,41 +151,14 @@ class Transformer {
       // nested class like `let Server = (() => { class Server {} })()`) is only
       // matched because `[id.name="Server"]` is broad.  It is not a function node
       // and should not be instrumented or counted toward the function index.
-      if (node.type === 'VariableDeclarator') return false
+      if (node.type === 'VariableDeclarator') return
 
       state.functionIndex = ++state.functionIndex || 0
 
-      if (index !== null && index !== state.functionIndex) return false
-    } else {
-      // For class nodes, validate that the method exists before instrumenting
-      const { methodName } = state.functionQuery
-      if (methodName) {
-        // Handle both ClassDeclaration/ClassExpression and VariableDeclarator with ClassExpression init
-        const classNode = node.type === 'VariableDeclarator' ? node.init : node
-        const classBody = classNode.body
-        const methodExists = classBody.body.some(({ key }) => key?.name === methodName)
-
-        if (!methodExists) {
-          // Method doesn't exist on the class. Check if any subclass has it.
-          const className = classNode.id?.name || node.id?.name
-          const program = ancestry[ancestry.length - 1]
-
-          if (className) {
-            const hasMethodInSubclass = esquery.query(
-              program,
-              `ClassDeclaration[superClass.name="${className}"] > ClassBody > MethodDefinition[key.name="${methodName}"]`
-            ).length > 0
-
-            if (!hasMethodInSubclass) {
-              throw new Error(`Method '${methodName}' not found on class '${className}' or any of its subclasses`)
-            }
-          }
-        }
-      }
+      if (index !== null && index !== state.functionIndex) return
     }
 
     transform(state, ...args)
-    return true
   }
 
   /**

tests/injection_failure/test.mjs

@@ -1,5 +1,9 @@
+/**
+ * Unless explicitly stated otherwise all files in this repository are licensed under the Apache-2.0 License.
+ * This product includes software developed at Datadog (https://www.datadoghq.com/). Copyright 2025 Datadog, Inc.
+ **/
 import { existsSync } from 'node:fs'
 import { assert } from '../common/preamble.js'
 
-const instrumented = existsSync('./instrumented.mjs')
-assert.strictEqual(instrumented, false, 'instrumented.mjs should not exist')
+const instrumented = existsSync('./instrumented.js')
+assert.strictEqual(instrumented, false, 'instrumented.js should not exist')

tests/injection_failure_method_name/mod.mjs

@@ -196,30 +196,6 @@ describe('injection_failure', () => {
   })
 })
 
-describe('injection_failure_method_name', () => {
-  test('does not write instrumented file when no injection points found', () => {
-    runTest('injection_failure_method_name', [
-      {
-        channelName: 'injection_failure_method_name',
-        module: { name: TEST_MODULE_NAME, versionRange: '>=0.0.1', filePath: TEST_MODULE_PATH },
-        functionQuery: { className: 'Foo', methodName: 'nonExistentMethod', kind: 'Async' },
-      },
-    ], { mjs: true })
-  })
-})
-
-describe('injection_failure_method_name_sub_class', () => {
-  test('does not write instrumented file when no injection points found', () => {
-    runTest('injection_failure_method_name_subclass', [
-      {
-        channelName: 'injection_failures_subclass_method_name',
-        module: { name: TEST_MODULE_NAME, versionRange: '>=0.0.1', filePath: TEST_MODULE_PATH },
-        functionQuery: { className: 'Base', methodName: 'nonExistentMethod', kind: 'Async' },
-      },
-    ], { mjs: true })
-  })
-})
-
 describe('multiple_class_method_cjs', () => {
   test('instruments multiple class methods', () => {
     runTest('multiple_class_method_cjs', [