chore: adds eslint rule to restrict import from config file

Author: himanshusinghs

eslint-rules/no-config-imports.js

@@ -0,0 +1,81 @@
+import path from "path";
+
+// Ref: https://eslint.org/docs/latest/extend/custom-rules
+export default {
+    meta: {
+        type: "problem",
+        docs: {
+            description:
+                "Disallows value imports from config.ts, with a few exceptions, to enforce dependency injection of the config.",
+            recommended: true,
+        },
+        fixable: null,
+        schema: [
+            {
+                type: "object",
+                properties: {
+                    configFilePath: {
+                        type: "string",
+                        description: "Path (relative to root of the project) to the config file to restrict.",
+                    },
+                    allowedFiles: {
+                        type: "array",
+                        items: { type: "string" },
+                        description:
+                            "List of file paths (relative to root of the project) that are allowed to import value exports from config.ts.",
+                    },
+                },
+                required: ["configFilePath"],
+            },
+        ],
+        messages: {
+            noConfigImports:
+                "Value imports from config.ts are not allowed. Use dependency injection instead. Only type imports are permitted.",
+        },
+    },
+    create(context) {
+        const options = context.options[0] || {};
+        const configFilePath = path.resolve(options.configFilePath);
+        const allowedFiles = options.allowedFiles || [];
+
+        const currentFilePath = path.resolve(context.getFilename());
+
+        const isCurrentFileAllowedToImport = allowedFiles.some((allowedFile) => {
+            const resolvedAllowedFile = path.resolve(allowedFile);
+            return currentFilePath === resolvedAllowedFile;
+        });
+
+        if (isCurrentFileAllowedToImport) {
+            return {};
+        }
+
+        return {
+            ImportDeclaration(node) {
+                const importPath = node.source.value;
+
+                // If the path is not relative, very likely its targeting a
+                // node_module so we skip it. And also if the entire import is
+                // marked with a type keyword.
+                if (typeof importPath !== "string" || !importPath.startsWith(".") || node.importKind === "type") {
+                    return;
+                }
+
+                const currentDir = path.dirname(currentFilePath);
+                const resolvedImportPath = path.resolve(currentDir, importPath);
+
+                if (resolvedImportPath === configFilePath) {
+                    const hasValueImportFromConfig = node.specifiers.some((specifier) => {
+                        return specifier.importKind !== "type";
+                    });
+
+                    if (hasValueImportFromConfig) {
+                        context.report({
+                            node,
+                            messageId: "noConfigImports",
+                        });
+                    }
+                }
+            },
+        };
+    },
+};

eslint-rules/no-config-imports.test.js

@@ -0,0 +1,79 @@
+import path from "path";
+import { RuleTester } from "eslint";
+import { describe, it } from "vitest";
+import tsParser from "@typescript-eslint/parser";
+import rule from "./no-config-imports.js";
+
+const ROOT = process.cwd();
+const resolve = (p) => path.resolve(ROOT, p);
+const CONFIG_FILE_PATH = resolve("src/common/config.js");
+const ALLOWED_CONFIG_VALUE_IMPORT_FILES = [resolve("src/index.ts"), resolve("src/resources/common/config.ts")];
+
+const ruleTester = new RuleTester({
+    languageOptions: {
+        parser: tsParser,
+        parserOptions: { ecmaVersion: 2022, sourceType: "module" },
+    },
+});
+
+describe("no-config-imports", () => {
+    it("should not report any violations", () => {
+        ruleTester.run("no-config-imports", rule, {
+            valid: [
+                {
+                    filename: resolve("src/some/module.ts"),
+                    code: 'import type { UserConfig } from "../common/config.js";\n',
+                    options: [{ configFilePath: CONFIG_FILE_PATH, allowedFiles: ALLOWED_CONFIG_VALUE_IMPORT_FILES }],
+                },
+                {
+                    filename: resolve("src/some/module.ts"),
+                    code: 'import { something } from "../common/logger.js";\n',
+                    options: [{ configFilePath: CONFIG_FILE_PATH, allowedFiles: ALLOWED_CONFIG_VALUE_IMPORT_FILES }],
+                },
+                {
+                    filename: resolve("src/some/module.ts"),
+                    code: 'import type * as Cfg from "../common/config.js";\n',
+                    options: [{ configFilePath: CONFIG_FILE_PATH, allowedFiles: ALLOWED_CONFIG_VALUE_IMPORT_FILES }],
+                },
+                {
+                    filename: ALLOWED_CONFIG_VALUE_IMPORT_FILES[1],
+                    code: 'import { driverOptions } from "../common/config.js";\n',
+                    options: [{ configFilePath: CONFIG_FILE_PATH, allowedFiles: ALLOWED_CONFIG_VALUE_IMPORT_FILES }],
+                },
+            ],
+            invalid: [],
+        });
+    });
+
+    it("should report rule violations", () => {
+        ruleTester.run("no-config-imports", rule, {
+            valid: [],
+            invalid: [
+                {
+                    filename: resolve("src/another/module.ts"),
+                    code: 'import { driverOptions } from "../common/config.js";\n',
+                    options: [{ configFilePath: CONFIG_FILE_PATH, allowedFiles: ALLOWED_CONFIG_VALUE_IMPORT_FILES }],
+                    errors: [{ messageId: "noConfigImports" }],
+                },
+                {
+                    filename: resolve("src/another/module.ts"),
+                    code: 'import configDefault from "../common/config.js";\n',
+                    options: [{ configFilePath: CONFIG_FILE_PATH, allowedFiles: ALLOWED_CONFIG_VALUE_IMPORT_FILES }],
+                    errors: [{ messageId: "noConfigImports" }],
+                },
+                {
+                    filename: resolve("src/another/module.ts"),
+                    code: 'import * as cfg from "../common/config.js";\n',
+                    options: [{ configFilePath: CONFIG_FILE_PATH, allowedFiles: ALLOWED_CONFIG_VALUE_IMPORT_FILES }],
+                    errors: [{ messageId: "noConfigImports" }],
+                },
+                {
+                    filename: resolve("src/another/module.ts"),
+                    code: 'import { type UserConfig, driverOptions } from "../common/config.js";\n',
+                    options: [{ configFilePath: CONFIG_FILE_PATH, allowedFiles: ALLOWED_CONFIG_VALUE_IMPORT_FILES }],
+                    errors: [{ messageId: "noConfigImports" }],
+                },
+            ],
+        });
+    });
+});

eslint.config.js

@@ -1,14 +1,27 @@
+import path from "path";
 import { defineConfig, globalIgnores } from "eslint/config";
 import js from "@eslint/js";
 import globals from "globals";
 import tseslint from "typescript-eslint";
 import eslintPluginPrettierRecommended from "eslint-plugin-prettier/recommended";
 import vitestPlugin from "@vitest/eslint-plugin";
+import noConfigImports from "./eslint-rules/no-config-imports.js";
 
 const testFiles = ["tests/**/*.test.ts", "tests/**/*.ts"];
 
 const files = [...testFiles, "src/**/*.ts", "scripts/**/*.ts"];
 
+// Files that are allowed to import value exports from config.ts
+const allowedConfigValueImportFiles = [
+    // Main entry point that injects the config
+    "src/index.ts",
+    // Config resource definition that works with the some config values
+    "src/resources/common/config.ts",
+];
+
+// Get the absolute path to the config file
+const configFilePath = path.resolve(import.meta.dirname, "src/common/config.js");
+
 export default defineConfig([
     { files, plugins: { js }, extends: ["js/recommended"] },
     { files, languageOptions: { globals: globals.node } },
@@ -62,6 +75,25 @@ export default defineConfig([
             "@typescript-eslint/explicit-function-return-type": "error",
         },
     },
+    {
+        files: ["src/**/*.ts"],
+        plugins: {
+            "no-config-imports": {
+                rules: {
+                    "no-config-imports": noConfigImports,
+                },
+            },
+        },
+        rules: {
+            "no-config-imports/no-config-imports": [
+                "error",
+                {
+                    configFilePath,
+                    allowedFiles: allowedConfigValueImportFiles,
+                },
+            ],
+        },
+    },
     globalIgnores([
         "node_modules",
         "dist",
@@ -72,6 +104,7 @@ export default defineConfig([
         "vitest.config.ts",
         "src/types/*.d.ts",
         "tests/integration/fixtures/",
+        "eslint-rules",
     ]),
     eslintPluginPrettierRecommended,
 ]);

package.json

@@ -52,7 +52,7 @@
     "fix:lint": "eslint . --fix",
     "reformat": "prettier --write .",
     "generate": "./scripts/generate.sh",
-    "test": "vitest --project unit-and-integration --coverage",
+    "test": "vitest --project eslint-rules --project unit-and-integration --coverage",
     "pretest:accuracy": "npm run build",
     "test:accuracy": "sh ./scripts/accuracy/runAccuracyTests.sh"
   },

vitest.config.ts

@@ -36,6 +36,13 @@ export default defineConfig({
                     include: ["**/accuracy/*.test.ts"],
                 },
             },
+            {
+                extends: true,
+                test: {
+                    name: "eslint-rules",
+                    include: ["eslint-rules/*.test.js"]
+                }
+            }
         ],
     },
 });