[new-rule] no-default-import

src/configs/all.ts

@@ -153,6 +153,7 @@ export const rules = {
  "max-file-line-count": [true, 1000],
  "max-line-length": [true, 120],
  "no-default-export": true,
+ "no-default-import": true,
  "no-duplicate-imports": true,
  "no-irregular-whitespace": true,
  "no-mergeable-namespace": true,

src/rules/noDefaultImportRule.ts

@@ -0,0 +1,130 @@
+/**
+ * @license
+ * Copyright 2016 Palantir Technologies, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { isImportDeclaration, isNamedImports, isStringLiteral } from "tsutils";
+import * as ts from "typescript";
+import * as Lint from "../index";
+
+const fromModulesConfigOptionName = "fromModules";
+interface RawConfigOptions {
+ [fromModulesConfigOptionName]: string;
+}
+interface Options {
+ [fromModulesConfigOptionName]: RegExp;
+}
+
+export class Rule extends Lint.Rules.AbstractRule {
+ /* tslint:disable:object-literal-sort-keys */
+ public static metadata: Lint.IRuleMetadata = {
+ ruleName: "no-default-import",
+ description: "Disallows importing default members from certain ES6-style modules.",
+ descriptionDetails: "Import named members instead.",
+ rationale: Lint.Utils.dedent`
+ Named imports/exports [promote clarity](https://github.com/palantir/tslint/issues/1182#issue-151780453).
+ In addition, current tooling differs on the correct way to handle default imports/exports.
+ Avoiding them all together can help avoid tooling bugs and conflicts.
+
+ The rule supposed to narrow the scope of your changes in the case of monorepo.
+ Say, you have packages \`A\`, \`B\`, \`C\` and \`utils\`, where \`A\`, \`B\`, \`C\` dependends on \`utils\`,
+ which is full of default exports.
+ \`"no-default-export"\` requires you to remove default _export_ from \`utils\`, which leads to changes
+ in packages \`A\`, \`B\`, \`C\`. It's harder to get merged bigger changeset by various reasons (harder to get your code approved
+ due to a number of required reviewers; longer build time due to a number of affected packages)
+ and could result in ignored \`"no-default-export"\` rule in \`utils'\`.
+
+ Unlike \`"no-default-export"\`, the rule requires you to repalce default _import_ with named only in \`A\` you work on,
+ and \`utils\` you import from.`,
+ optionsDescription: "optionsDescription",
+ options: {
+ type: "array",
+ items: {
+ type: "object",
+ properties: {
+ [fromModulesConfigOptionName]: { type: "string" },
+ },
+ required: [
+ "fromModules",
+ ],
+ },
+ },
+ optionExamples: [
+ [true, { [fromModulesConfigOptionName]: "^palantir-|^_internal-*|^\\./|^\\.\\./" }],
+ ],
+ type: "maintainability",
+ typescriptOnly: false,
+ };
+ /* tslint:enable:object-literal-sort-keys */
+
+ public static FAILURE_STRING = "Import of default members from this module is forbidden. Import named member instead";
+
+ public static getNamedDefaultImport(namedBindings: ts.NamedImports): ts.Identifier | null {
+ for (const importSpecifier of namedBindings.elements) {
+ if (importSpecifier.propertyName !== undefined && importSpecifier.propertyName.text === "default") {
+ return importSpecifier.propertyName;
+ }
+ }
+ return null;
+ }
+
+ public apply(sourceFile: ts.SourceFile): Lint.RuleFailure[] {
+ return this.applyWithFunction(sourceFile, walk, this.getRuleOptions(this.ruleArguments));
+ }
+ private isFromModulesConfigOption(option: boolean | RawConfigOptions): option is RawConfigOptions {
+ return typeof option === "object" && option[fromModulesConfigOptionName] !== undefined;
+ }
+ private getRuleOptions(options: ReadonlyArray<boolean | RawConfigOptions>): Options {
+ const fromModuleConfigOption = options.find<RawConfigOptions>(this.isFromModulesConfigOption);
+ if (fromModuleConfigOption !== undefined && typeof fromModuleConfigOption[fromModulesConfigOptionName] === "string") {
+ return {
+ [fromModulesConfigOptionName]: new RegExp(fromModuleConfigOption[fromModulesConfigOptionName]),
+ };
+ } else {
+ return {
+ [fromModulesConfigOptionName]: new RegExp("^\\./|^\\.\\./"),
+ };
+ }
+ }
+}
+
+function walk(ctx: Lint.WalkContext<Options>) {
+ if (ctx.sourceFile.isDeclarationFile || !ts.isExternalModule(ctx.sourceFile)) {
+ return;
+ }
+ for (const statement of ctx.sourceFile.statements) {
+ if (isImportDeclaration(statement)) {
+ const { importClause, moduleSpecifier } = statement;
+ if (
+ importClause !== undefined
+ && isStringLiteral(moduleSpecifier)
+ && ctx.options[fromModulesConfigOptionName].test(moduleSpecifier.text)
+ ) {
+ // module name matches specified in rule config
+ if (importClause.name !== undefined) {
+ // `import Foo...` syntax
+ const defaultImportedName = importClause.name;
+ ctx.addFailureAtNode(defaultImportedName, Rule.FAILURE_STRING);
+ } else if (importClause.namedBindings !== undefined && isNamedImports(importClause.namedBindings)) {
+ // `import { default...` syntax
+ const defaultMember = Rule.getNamedDefaultImport(importClause.namedBindings);
+ if (defaultMember !== null) {
+ ctx.addFailureAtNode(defaultMember, Rule.FAILURE_STRING);
+ }
+ }
+ }
+ }
+ }
+}

test/rules/no-default-import/default/test.ts.lint

@@ -0,0 +1,36 @@
+import * as Utils from "tslint-utils"
+
+import TslintUtils from "tslint-utils"
+
+import Bar, { Foo } from "tslint-misc"
+
+import Bar, * as Foo from "tslint-misc"
+
+import { default as Foo } from "tslint-misc"
+
+import { default as foo, bar } from "tslint-misc"
+
+import { bar, default as foo } from "tslint-misc"
+
+import TslintUtils from "../tslint-utils"
+ ~~~~~~~~~~~ [0]
+
+import TslintUtils from "./tslint-utils"
+ ~~~~~~~~~~~ [0]
+
+import Bar, { Foo } from "../tslint-misc"
+ ~~~ [0]
+
+import Bar, * as Foo from "./tslint-misc"
+ ~~~ [0]
+
+import { default as Foo } from "../tslint-misc"
+ ~~~~~~~ [0]
+
+import { default as foo, bar } from "./tslint-misc"
+ ~~~~~~~ [0]
+
+import { bar, default as foo } from "../tslint-misc"
+ ~~~~~~~ [0]
+
+[0]: Import of default members from this module is forbidden. Import named member instead

test/rules/no-default-import/default/tslint.json

@@ -0,0 +1,5 @@
+{
+ "rules": {
+ "no-default-import": true
+ }
+}

test/rules/no-default-import/fromModules/test.ts.lint

@@ -0,0 +1,24 @@
+import * as Utils from "tslint-utils"
+
+import TslintUtils from "../tslint-utils"
+ ~~~~~~~~~~~ [0]
+
+import TslintUtils from "tslint-utils"
+ ~~~~~~~~~~~ [0]
+
+import Bar, { Foo } from "tslint-misc"
+ ~~~ [0]
+
+import Bar, * as Foo from "tslint-misc"
+ ~~~ [0]
+
+import { default as Foo } from "tslint-misc"
+ ~~~~~~~ [0]
+
+import { default as foo, bar } from "tslint-misc"
+ ~~~~~~~ [0]
+
+import { bar, default as foo } from "tslint-misc"
+ ~~~~~~~ [0]
+
+[0]: Import of default members from this module is forbidden. Import named member instead

test/rules/no-default-import/fromModules/tslint.json

@@ -0,0 +1,10 @@
+{
+ "rules": {
+ "no-default-import": [
+ true,
+ {
+ "fromModules": "^tslint-|^\\./|^\\.\\./"
+ }
+ ]
+ }
+}