implement custom lint rule

Author: Hweinstock

.eslintrc.js

@@ -162,7 +162,7 @@ module.exports = {
         'aws-toolkits/no-incorrect-once-usage': 'error',
         'aws-toolkits/no-string-exec-for-child-process': 'error',
         'aws-toolkits/no-console-log': 'error',
-
+        'aws-toolkits/no-json-stringify-in-log': 'error',
         'no-restricted-imports': [
             'error',
             {

plugins/eslint-plugin-aws-toolkits/index.ts

@@ -9,6 +9,7 @@ import NoIncorrectOnceUsage from './lib/rules/no-incorrect-once-usage'
 import NoOnlyInTests from './lib/rules/no-only-in-tests'
 import NoStringExecForChildProcess from './lib/rules/no-string-exec-for-child-process'
 import NoConsoleLog from './lib/rules/no-console-log'
+import noJsonStringifyInLog from './lib/rules/no-json-stringify-in-log'
 
 const rules = {
     'no-await-on-vscode-msg': NoAwaitOnVscodeMsg,
@@ -17,6 +18,7 @@ const rules = {
     'no-only-in-tests': NoOnlyInTests,
     'no-string-exec-for-child-process': NoStringExecForChildProcess,
     'no-console-log': NoConsoleLog,
+    'no-json-stringify-in-log': noJsonStringifyInLog,
 }
 
 export { rules }

plugins/eslint-plugin-aws-toolkits/lib/rules/no-json-stringify-in-log.ts

@@ -0,0 +1,72 @@
+/*!
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { AST_NODE_TYPES, ESLintUtils } from '@typescript-eslint/utils'
+import { Rule } from 'eslint'
+
+export const errMsg = 'Avoid using JSON.stringify within logging and error messages, prefer %O.'
+
+function isJsonStringifyCall(node: any) {
+    return (
+        node.type === AST_NODE_TYPES.CallExpression &&
+        node.callee.type === AST_NODE_TYPES.MemberExpression &&
+        node.callee.object.type === AST_NODE_TYPES.Identifier &&
+        node.callee.object.name === 'JSON' &&
+        node.callee.property.type === AST_NODE_TYPES.Identifier &&
+        node.callee.property.name === 'stringify'
+    )
+}
+
+export default ESLintUtils.RuleCreator.withoutDocs({
+    meta: {
+        docs: {
+            description: 'disallow use of JSON.stringify in logs and errors, to encourage use %O',
+            recommended: 'recommended',
+        },
+        messages: {
+            errMsg,
+        },
+        type: 'problem',
+        fixable: 'code',
+        schema: [],
+    },
+    defaultOptions: [],
+    create(context) {
+        return {
+            CallExpression(node) {
+                // Look for a getLogger().f() call.
+                if (
+                    node.callee.type === AST_NODE_TYPES.MemberExpression &&
+                    node.callee.object.type === AST_NODE_TYPES.CallExpression &&
+                    node.callee.object.callee.type === AST_NODE_TYPES.Identifier &&
+                    node.callee.object.callee.name === 'getLogger'
+                ) {
+                    // For each argument to the call above, check if it contains a JSON.stringify
+                    node.arguments.forEach((arg) => {
+                        // Check if arg itself if a JSON.stringify call
+                        if (isJsonStringifyCall(arg)) {
+                            return context.report({
+                                node: node,
+                                messageId: 'errMsg',
+                            })
+                        }
+                        // Check if the arg contains a template ex. '${...}'
+                        if (arg.type === AST_NODE_TYPES.TemplateLiteral) {
+                            arg.expressions.forEach((e) => {
+                                // Check the template for a JSON.stringify call.
+                                if (isJsonStringifyCall(e)) {
+                                    return context.report({
+                                        node: node,
+                                        messageId: 'errMsg',
+                                    })
+                                }
+                            })
+                        }
+                    })
+                }
+            },
+        }
+    },
+}) as unknown as Rule.RuleModule

plugins/eslint-plugin-aws-toolkits/test/rules/no-json-stringify-in-log.test.ts

@@ -0,0 +1,41 @@
+/*!
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { rules } from '../../index'
+import { errMsg } from '../../lib/rules/no-json-stringify-in-log'
+import { getRuleTester } from '../testUtil'
+
+getRuleTester().run('no-json-stringify-in-log', rules['no-json-stringify-in-log'], {
+    valid: [
+        'getLogger().debug(`the object is %O`)',
+        'return JSON.stringify(d)',
+        'getLogger().debug(`this does not include anything`)',
+        'getLogger().debug(`another example ${JSON.notString(something)}`)',
+        'getLogger().fakeFunction(`another example ${JSON.notString(something)}`)',
+    ],
+
+    invalid: [
+        {
+            code: 'getLogger().debug(`the object is ${JSON.stringify(obj)}`)',
+            errors: [errMsg],
+        },
+        {
+            code: 'getLogger().debug(`the object is ${notThis} but ${JSON.stringify(obj)}`)',
+            errors: [errMsg],
+        },
+        {
+            code: 'getLogger().debug(`the object is ${notThis} or ${thisOne} but ${JSON.stringify(obj)}`)',
+            errors: [errMsg],
+        },
+        {
+            code: 'getLogger().verbose(`Invalid Request : `, JSON.stringify(request, undefined, EditorContext.getTabSize()))',
+            errors: [errMsg],
+        },
+        {
+            code: 'getLogger().verbose(`provideDebugConfigurations: debugconfigs: ${JSON.stringify(configs)}`)',
+            errors: [errMsg],
+        },
+    ],
+})