Merge pull request #161 from ext/refactor/strict-null-checks

refactor: enable strictNullChecks

src/index.ts

@@ -25,8 +25,8 @@ interface ParsedArgs {
 }
 
 interface GetPackageJsonResults {
-	pkg?: PackageJson;
-	pkgPath?: string;
+	pkg: PackageJson;
+	pkgPath: string;
 }
 
 async function preloadStdin(): Promise<string> {
@@ -37,7 +37,7 @@ async function preloadStdin(): Promise<string> {
 				return;
 			}
 
-			const st = createWriteStream(null, { fd, autoClose: true });
+			const st = createWriteStream("", { fd, autoClose: true });
 			process.stdin.pipe(st);
 			st.on("finish", () => {
 				resolve(path);
@@ -52,7 +52,7 @@ async function preloadStdin(): Promise<string> {
 async function getPackageJson(
 	args: ParsedArgs,
 	regenerateReportName: boolean
-): Promise<GetPackageJsonResults> {
+): Promise<GetPackageJsonResults | Record<string, never>> {
 	/* get from explicit path passed as argument */
 	if (args.pkgfile) {
 		return {

src/package-json.spec.ts

@@ -7,7 +7,7 @@ import { npmInfoMockDefault } from "./utils/npm-info";
 
 jest.mock("./utils/npm-info");
 
-let pkg: PackageJson;
+let pkg: PackageJson & Required<Pick<PackageJson, "engines">>;
 
 beforeEach(() => {
 	pkg = {

src/rules/outdated-engines.spec.ts

@@ -28,7 +28,9 @@ describe("should return error when unsupported version satisfies engines.node",
 		${">= 12.x"}   | ${"Node 12"}
 	`("$description", ({ range, description }) => {
 		expect.assertions(1);
-		pkg.engines.node = range;
+		pkg.engines = {
+			node: range,
+		};
 		/* eslint-disable-next-line security/detect-non-literal-regexp -- not under user control */
 		const message = new RegExp(
 			String.raw`engines\.node is satisfied by ${description} \(EOL since \d{4}-.*\)`
@@ -47,7 +49,9 @@ describe("should return error when unsupported version satisfies engines.node",
 
 it("should return error engines.node is not a valid semver range", () => {
 	expect.assertions(1);
-	pkg.engines.node = "foobar";
+	pkg.engines = {
+		node: "foobar",
+	};
 	expect(Array.from(outdatedEngines(pkg))).toMatchInlineSnapshot(`
 		[
 		  {
@@ -63,7 +67,7 @@ it("should return error engines.node is not a valid semver range", () => {
 
 it("should return error engines.node is missing", () => {
 	expect.assertions(1);
-	delete pkg.engines.node;
+	pkg.engines = {};
 	expect(Array.from(outdatedEngines(pkg))).toMatchInlineSnapshot(`
 		[
 		  {
@@ -95,6 +99,8 @@ it("should return error engines is missing", () => {
 
 it("should not return error when engines.node only supports active versions", () => {
 	expect.assertions(1);
-	pkg.engines.node = ">= 14";
+	pkg.engines = {
+		node: ">= 14",
+	};
 	expect(Array.from(outdatedEngines(pkg))).toMatchInlineSnapshot(`[]`);
 });

src/rules/outdated-engines.ts

@@ -41,7 +41,7 @@ export function* outdatedEngines(pkg: PackageJson): Generator<Message> {
 		if (!semver.satisfies(expanded, range)) {
 			continue;
 		}
-		const nodeRelease = parsed.major || `0.${parsed.minor}`;
+		const nodeRelease = parsed?.major || `0.${parsed?.minor}`;
 		const message = `engines.node is satisfied by Node ${nodeRelease} (EOL since ${descriptor.eol})`;
 		yield {
 			ruleId,

src/rules/types-node-matching-engine.spec.ts

@@ -1,20 +1,21 @@
 import PackageJson from "../types/package-json";
 import { typesNodeMatchingEngine } from "./types-node-matching-engine";
 
-let pkg: PackageJson;
+let pkg: PackageJson & Required<Pick<PackageJson, "engines">>;
 
 beforeEach(() => {
 	pkg = {
 		name: "mock-package",
 		version: "1.2.3",
-		devDependencies: {},
 		engines: {},
 	};
 });
 
 it("should return error when engine is lower major than types", () => {
 	expect.assertions(1);
-	pkg.devDependencies["@types/node"] = "^14.1.2";
+	pkg.devDependencies = {
+		"@types/node": "^14.1.2",
+	};
 	pkg.engines.node = ">= 12";
 	expect(Array.from(typesNodeMatchingEngine(pkg))).toMatchInlineSnapshot(`
 		[
@@ -31,7 +32,9 @@ it("should return error when engine is lower major than types", () => {
 
 it("should return error when engine is higher major than types", () => {
 	expect.assertions(1);
-	pkg.devDependencies["@types/node"] = "^12.1.2";
+	pkg.devDependencies = {
+		"@types/node": "^12.1.2",
+	};
 	pkg.engines.node = ">= 14";
 	expect(Array.from(typesNodeMatchingEngine(pkg))).toMatchInlineSnapshot(`
 		[
@@ -48,14 +51,18 @@ it("should return error when engine is higher major than types", () => {
 
 it("should not return error when engine and types have same major", () => {
 	expect.assertions(1);
-	pkg.devDependencies["@types/node"] = "^12.1.2";
+	pkg.devDependencies = {
+		"@types/node": "^12.1.2",
+	};
 	pkg.engines.node = ">= 12";
 	expect(Array.from(typesNodeMatchingEngine(pkg))).toEqual([]);
 });
 
 it("should handle || in engine constraint", () => {
 	expect.assertions(1);
-	pkg.devDependencies["@types/node"] = "^14.1.2";
+	pkg.devDependencies = {
+		"@types/node": "^14.1.2",
+	};
 	pkg.engines.node = "^10.2.3 || ^12.2.3 || 14.2.3";
 	expect(Array.from(typesNodeMatchingEngine(pkg))).toMatchInlineSnapshot(`
 		[

src/rules/verify-engine-constraint.ts

@@ -29,6 +29,10 @@ export async function verifyEngineConstraint(pkg: PackageJson): Promise<Message[
 	}
 
 	const minDeclared = semver.minVersion(declaredConstraint);
+	if (!minDeclared) {
+		throw new Error(`Failed to parse engine constraint "${declaredConstraint}"`);
+	}
+
 	const messages: Message[] = [];
 
 	for await (const dependency of getDeepDependencies(pkg)) {

src/utils/__mocks__/npm-info.ts

@@ -4,8 +4,9 @@ const mock: Map<string, PackageJson> = new Map();
 let defaultInfo: PackageJson | null = null;
 
 export async function npmInfo(pkg: string): Promise<PackageJson> {
-	if (mock.has(pkg)) {
-		return mock.get(pkg);
+	const mocked = mock.get(pkg);
+	if (mocked) {
+		return mocked;
 	} else if (defaultInfo) {
 		return defaultInfo;
 	} else {

src/utils/npm-info.ts

@@ -4,8 +4,9 @@ import PackageJson from "../types/package-json";
 const cache: Map<string, PackageJson> = new Map();
 
 export async function npmInfo(pkg: string): Promise<PackageJson> {
-	if (cache.has(pkg)) {
-		return cache.get(pkg);
+	const cached = cache.get(pkg);
+	if (cached) {
+		return cached;
 	}
 
 	const result = await execa("npm", ["info", "--json", pkg]);

tsconfig.json

@@ -13,8 +13,7 @@
     "resolveJsonModule": true,
     "sourceMap": true,
     "target": "es2017",
-    "strict": true,
-    "strictNullChecks": false
+    "strict": true
   },
   "include": ["src/**/*.ts"],
   "exclude": ["node_modules", "**/__mocks__"]