Refactor and fix no-inferred-empty-object-type (#2762)

[bugfix] no-inferred-empty-object-type: fix stack overflow
[develop]: rule tests now support imports of node_modules

src/rules/noInferredEmptyObjectTypeRule.ts

@@ -15,9 +15,9 @@
  * limitations under the License.
  */
 
+import { isObjectFlagSet, isObjectType, isTypeReference } from "tsutils";
 import * as ts from "typescript";
 import * as Lint from "../index";
-import { isObjectFlagSet, isTypeFlagSet } from "../language/utils";
 
 export class Rule extends Lint.Rules.TypedRule {
     /* tslint:disable:object-literal-sort-keys */
@@ -60,12 +60,10 @@ class NoInferredEmptyObjectTypeRule extends Lint.AbstractWalker<void> {
 
     private checkNewExpression(node: ts.NewExpression): void {
         if (node.typeArguments === undefined) {
-            const objType = this.checker.getTypeAtLocation(node) as ts.TypeReference;
-            if (isTypeFlagSet(objType, ts.TypeFlags.Object) && objType.typeArguments !== undefined) {
-                const typeArgs = objType.typeArguments as ts.ObjectType[];
-                if (typeArgs.some((a) => this.isEmptyObjectInterface(a))) {
-                    this.addFailureAtNode(node, Rule.EMPTY_INTERFACE_INSTANCE);
-                }
+            const type = this.checker.getTypeAtLocation(node);
+            if (isTypeReference(type) && type.typeArguments !== undefined &&
+                type.typeArguments.some((a) => isObjectType(a) && this.isEmptyObjectInterface(a))) {
+                this.addFailureAtNode(node, Rule.EMPTY_INTERFACE_INSTANCE);
             }
         }
     }
@@ -80,28 +78,20 @@ class NoInferredEmptyObjectTypeRule extends Lint.AbstractWalker<void> {
             return;
         }
 
-        const retType = this.checker.getReturnTypeOfSignature(callSig) as ts.TypeReference;
-        if (this.isEmptyObjectInterface(retType)) {
+        const retType = this.checker.getReturnTypeOfSignature(callSig);
+        if (isObjectType(retType) && this.isEmptyObjectInterface(retType)) {
             this.addFailureAtNode(node, Rule.EMPTY_INTERFACE_FUNCTION);
         }
     }
 
     private isEmptyObjectInterface(objType: ts.ObjectType): boolean {
-        const isAnonymous = isObjectFlagSet(objType, ts.ObjectFlags.Anonymous);
-        let hasProblematicCallSignatures = false;
-        const hasProperties = (objType.getProperties() !== undefined && objType.getProperties().length > 0);
-        const hasNumberIndexType = objType.getNumberIndexType() !== undefined;
-        const hasStringIndexType = objType.getStringIndexType() !== undefined;
-        const callSig = objType.getCallSignatures();
-        if (callSig !== undefined && callSig.length > 0) {
-            const isClean = callSig.every((sig) => {
-                const csigRetType = this.checker.getReturnTypeOfSignature(sig) as ts.TypeReference;
-                return this.isEmptyObjectInterface(csigRetType);
+        return isObjectFlagSet(objType, ts.ObjectFlags.Anonymous) &&
+            objType.getProperties().length === 0 &&
+            objType.getNumberIndexType() === undefined &&
+            objType.getStringIndexType() === undefined &&
+            objType.getCallSignatures().every((signature) => {
+                const type = this.checker.getReturnTypeOfSignature(signature);
+                return isObjectType(type) && this.isEmptyObjectInterface(type);
             });
-            if (!isClean) {
-                hasProblematicCallSignatures = true;
-            }
-        }
-        return (isAnonymous && !hasProblematicCallSignatures && !hasProperties && !hasNumberIndexType && !hasStringIndexType);
     }
 }

src/test.ts

@@ -27,7 +27,7 @@ import {Replacement} from "./language/rule/rule";
 import * as Linter from "./linter";
 import {LintError} from "./test/lintError";
 import * as parse from "./test/parse";
-import {mapDefined, readBufferWithDetectedEncoding} from "./utils";
+import {denormalizeWinPath, mapDefined, readBufferWithDetectedEncoding} from "./utils";
 
 const MARKUP_FILE_EXTENSION = ".lint";
 const FIXES_FILE_EXTENSION = ".fix";
@@ -90,8 +90,7 @@ export function runTest(testDirectory: string, rulesDirectory?: string | string[
     for (const fileToLint of filesToLint) {
         const isEncodingRule = path.basename(testDirectory) === "encoding";
 
-        const fileBasename = path.basename(fileToLint, MARKUP_FILE_EXTENSION);
-        const fileCompileName = fileBasename.replace(/\.lint$/, "");
+        const fileCompileName = denormalizeWinPath(path.resolve(fileToLint.replace(/\.lint$/, "")));
         let fileText = isEncodingRule ? readBufferWithDetectedEncoding(fs.readFileSync(fileToLint)) : fs.readFileSync(fileToLint, "utf-8");
         const tsVersionRequirement = parse.getTypescriptVersionRequirement(fileText);
         if (tsVersionRequirement !== undefined) {
@@ -114,26 +113,24 @@ export function runTest(testDirectory: string, rulesDirectory?: string | string[
         let program: ts.Program | undefined;
         if (hasConfig) {
             const compilerHost: ts.CompilerHost = {
-                fileExists: () => true,
-                getCanonicalFileName: (filename: string) => filename,
-                getCurrentDirectory: () => "",
+                fileExists: (file) => file === fileCompileName || fs.existsSync(file),
+                getCanonicalFileName: (filename) => filename,
+                getCurrentDirectory: () => process.cwd(),
                 getDefaultLibFileName: () => ts.getDefaultLibFileName(compilerOptions),
-                getDirectories: (_path: string) => [],
+                getDirectories: (path) => fs.readdirSync(path),
                 getNewLine: () => "\n",
-                getSourceFile(filenameToGet: string) {
+                getSourceFile(filenameToGet) {
                     const target = compilerOptions.target === undefined ? ts.ScriptTarget.ES5 : compilerOptions.target;
                     if (filenameToGet === ts.getDefaultLibFileName(compilerOptions)) {
                         const fileContent = fs.readFileSync(ts.getDefaultLibFilePath(compilerOptions), "utf8");
                         return ts.createSourceFile(filenameToGet, fileContent, target);
-                    } else if (filenameToGet === fileCompileName) {
-                        return ts.createSourceFile(fileBasename, fileTextWithoutMarkup, target, true);
-                    } else if (fs.existsSync(path.resolve(path.dirname(fileToLint), filenameToGet))) {
-                        const text = fs.readFileSync(path.resolve(path.dirname(fileToLint), filenameToGet), "utf8");
-                        return ts.createSourceFile(filenameToGet, text, target, true);
+                    } else if (denormalizeWinPath(filenameToGet) === fileCompileName) {
+                        return ts.createSourceFile(filenameToGet, fileTextWithoutMarkup, target, true);
                     }
-                    throw new Error(`Couldn't get source file '${filenameToGet}'`);
+                    const text = fs.readFileSync(filenameToGet, "utf8");
+                    return ts.createSourceFile(filenameToGet, text, target, true);
                 },
-                readFile: (x: string) => x,
+                readFile: (x) => x,
                 useCaseSensitiveFileNames: () => true,
                 writeFile: () => null,
             };
@@ -149,7 +146,7 @@ export function runTest(testDirectory: string, rulesDirectory?: string | string[
         };
         const linter = new Linter(lintOptions, program);
         // Need to use the true path (ending in '.lint') for "encoding" rule so that it can read the file.
-        linter.lint(isEncodingRule ? fileToLint : fileBasename, fileTextWithoutMarkup, tslintConfig);
+        linter.lint(isEncodingRule ? fileToLint : fileCompileName, fileTextWithoutMarkup, tslintConfig);
         const failures = linter.getResult().failures;
         const errorsFromLinter: LintError[] = failures.map((failure) => {
             const startLineAndCharacter = failure.getStartPosition().getLineAndCharacter();

src/utils.ts

@@ -209,3 +209,8 @@ export function detectBufferEncoding(buffer: Buffer, length = buffer.length): En
 
     return "utf8";
 }
+
+// converts Windows normalized paths (with backwards slash `\`) to paths used by TypeScript (with forward slash `/`)
+export function denormalizeWinPath(path: string): string {
+    return path.replace(/\\/g, "/");
+}

test/executable/executableTests.ts

@@ -19,7 +19,8 @@ import * as cp from "child_process";
 import * as fs from "fs";
 import * as os from "os";
 import * as path from "path";
-import { createTempFile, denormalizeWinPath } from "../utils";
+import { denormalizeWinPath } from "../../src/utils";
+import { createTempFile } from "../utils";
 
 // when tests are run with mocha from npm scripts CWD points to project root
 const EXECUTABLE_DIR = path.resolve(process.cwd(), "test", "executable");

test/rules/no-inferred-empty-object-type/test.ts.lint

@@ -84,3 +84,7 @@ new MultiParamsClass<() => void, () => {}>();
 new MultiParamsClass<() => void, () => void>();
 new MultiParamsClass<{ [x: number]: string }, () => void>();
 new MultiParamsClass<{ [x: string]: string }, number>();
+
+// don't crash with stack overflow
+import {expect} from "chai";
+expect(1).to.eq(1);

test/utils.ts

@@ -47,8 +47,3 @@ export function createTempFile(extension: string) {
     }
     return tmpfile;
 }
-
-// converts Windows normalized paths (with backwards slash `\`) to paths used by TypeScript (with forward slash `/`)
-export function denormalizeWinPath(path: string): string {
-    return path.replace(/\\/g, "/");
-}