no-null/no-null

.eslintrc

@@ -12,7 +12,7 @@
         "es6": true
     },
     "plugins": [
-        "@typescript-eslint", "microsoft-typescript", "import"
+        "@typescript-eslint", "microsoft-typescript", "no-null", "import"
     ],
     "rules": {
         "@typescript-eslint/adjacent-overload-signatures": "error",
@@ -56,6 +56,7 @@
         "@typescript-eslint/type-annotation-spacing": "error",
         "@typescript-eslint/unified-signatures": "error",
 
+        /** eslint-plugin-microsoft-typescript */
         "microsoft-typescript/object-literal-surrounding-space": "error",
         "microsoft-typescript/no-type-assertion-whitespace": "error",
         "microsoft-typescript/type-operator-spacing": "error",
@@ -69,9 +70,11 @@
         "microsoft-typescript/debug-assert": "error",
         "microsoft-typescript/no-keywords": "error",
 
-        "import/no-extraneous-dependencies": ["error", {
-            "optionalDependencies": false
-        }],
+        /** eslint-plugin-import */
+        "import/no-extraneous-dependencies": ["error", { "optionalDependencies": false }],
+
+        /** eslint-plugin-no-null */
+        "no-null/no-null": "error",
 
         "arrow-body-style": "off",
         "arrow-parens": "off",

package.json

@@ -68,6 +68,7 @@
         "eslint-formatter-autolinkable-stylish": "latest",
         "eslint-plugin-import": "2.18.0",
         "eslint-plugin-microsoft-typescript": "0.1.11",
+        "eslint-plugin-no-null": "1.0.2",
         "fancy-log": "latest",
         "fs-extra": "^6.0.1",
         "glob": "latest",

scripts/configurePrerelease.ts

@@ -52,6 +52,7 @@ function main(): void {
     writeFileSync(tsFilePath, modifiedTsFileContents);
 }
 
+/* eslint-disable no-null/no-null */
 function updateTsFile(tsFilePath: string, tsFileContents: string, majorMinor: string, patch: string, nightlyPatch: string): string {
     const majorMinorRgx = /export const versionMajorMinor = "(\d+\.\d+)"/;
     const majorMinorMatch = majorMinorRgx.exec(tsFileContents);
@@ -76,6 +77,7 @@ function parsePackageJsonVersion(versionString: string): { majorMinor: string, p
     assert(match !== null, "package.json 'version' should match " + versionRgx.toString());
     return { majorMinor: match![1], patch: match![2] };
 }
+/* eslint-enable no-null/no-null */
 
 /** e.g. 0-dev.20170707 */
 function getPrereleasePatch(tag: string, plainPatch: string): string {

src/compiler/commandLineParser.ts

@@ -1642,7 +1642,7 @@ namespace ts {
 
                 case SyntaxKind.NullKeyword:
                     reportInvalidOptionValue(option && option.name === "extends"); // "extends" is the only option we don't allow null/undefined for
-                    return null;
+                    return null; // eslint-disable-line no-null/no-null
 
                 case SyntaxKind.StringLiteral:
                     if (!isDoubleQuotedString(valueExpression)) {
@@ -2013,7 +2013,7 @@ namespace ts {
     }
 
     function isNullOrUndefined(x: any): x is null | undefined {
-        return x === undefined || x === null;
+        return x === undefined || x === null; // eslint-disable-line no-null/no-null
     }
 
     function directoryOfCombinedPath(fileName: string, basePath: string) {

src/compiler/core.ts

@@ -74,7 +74,7 @@ namespace ts {
 
     /** Create a MapLike with good performance. */
     function createDictionaryObject<T>(): MapLike<T> {
-        const map = Object.create(/*prototype*/ null);
+        const map = Object.create(/*prototype*/ null); // eslint-disable-line no-null/no-null
 
         // Using 'delete' on an object causes V8 to put the object in dictionary mode.
         // This disables creation of hidden classes, which are expensive when an object is

src/compiler/debug.ts

@@ -54,6 +54,7 @@ namespace ts {
         }
 
         export function assertDefined<T>(value: T | null | undefined, message?: string): T {
+            // eslint-disable-next-line no-null/no-null
             if (value === undefined || value === null) return fail(message);
             return value;
         }

src/compiler/moduleNameResolver.ts

@@ -130,8 +130,9 @@ namespace ts {
             return;
         }
         const value = jsonContent[fieldName];
-        if (typeof value !== typeOfTag || value === null) {
+        if (typeof value !== typeOfTag || value === null) { // eslint-disable-line no-null/no-null
             if (state.traceEnabled) {
+                // eslint-disable-next-line no-null/no-null
                 trace(state.host, Diagnostics.Expected_type_of_0_field_in_package_json_to_be_1_got_2, fieldName, typeOfTag, value === null ? "null" : typeof value);
             }
             return;
@@ -420,6 +421,7 @@ namespace ts {
                             const packageJsonPath = combinePaths(root, normalized, "package.json");
                             // `types-publisher` sometimes creates packages with `"typings": null` for packages that don't provide their own types.
                             // See `createNotNeededPackageJSON` in the types-publisher` repo.
+                            // eslint-disable-next-line no-null/no-null
                             const isNotNeededPackage = host.fileExists(packageJsonPath) && (readJson(packageJsonPath, host) as PackageJson).typings === null;
                             if (!isNotNeededPackage) {
                                 const baseFileName = getBaseFileName(normalized);

src/compiler/program.ts

@@ -2084,7 +2084,7 @@ namespace ts {
 
             function collectDynamicImportOrRequireCalls(file: SourceFile) {
                 const r = /import|require/g;
-                while (r.exec(file.text) !== null) {
+                while (r.exec(file.text) !== null) { // eslint-disable-line no-null/no-null
                     const node = getNodeAtPosition(file, r.lastIndex);
                     if (isRequireCall(node, /*checkArgumentIsStringLiteralLike*/ true)) {
                         imports = append(imports, node.arguments[0]);
@@ -3094,7 +3094,7 @@ namespace ts {
 
         function getCompilerOptionsObjectLiteralSyntax() {
             if (_compilerOptionsObjectLiteralSyntax === undefined) {
-                _compilerOptionsObjectLiteralSyntax = null;
+                _compilerOptionsObjectLiteralSyntax = null; // eslint-disable-line no-null/no-null
                 const jsonObjectLiteral = getTsConfigObjectLiteralExpression(options.configFile);
                 if (jsonObjectLiteral) {
                     for (const prop of getPropertyAssignment(jsonObjectLiteral, "compilerOptions")) {

src/compiler/sourcemap.ts

@@ -68,18 +68,19 @@ namespace ts {
             return sourceIndex;
         }
 
+        /* eslint-disable microsoft-typescript/boolean-trivia, no-null/no-null */
         function setSourceContent(sourceIndex: number, content: string | null) {
             enter();
             if (content !== null) {
                 if (!sourcesContent) sourcesContent = [];
                 while (sourcesContent.length < sourceIndex) {
-                    // eslint-disable-next-line microsoft-typescript/boolean-trivia
                     sourcesContent.push(null);
                 }
                 sourcesContent[sourceIndex] = content;
             }
             exit();
         }
+        /* eslint-enable microsoft-typescript/boolean-trivia, no-null/no-null */
 
         function addName(name: string) {
             enter();
@@ -309,6 +310,7 @@ namespace ts {
         }
     }
 
+    /* eslint-disable no-null/no-null */
     function isStringOrNull(x: any) {
         return typeof x === "string" || x === null;
     }
@@ -324,6 +326,7 @@ namespace ts {
             && (x.sourcesContent === undefined || x.sourcesContent === null || isArray(x.sourcesContent) && every(x.sourcesContent, isStringOrNull))
             && (x.names === undefined || x.names === null || isArray(x.names) && every(x.names, isString));
     }
+    /* eslint-enable no-null/no-null */
 
     export function tryParseRawSourceMap(text: string) {
         try {

src/compiler/utilities.ts

@@ -8623,6 +8623,7 @@ namespace ts {
     }
 
     export function isJsonEqual(a: unknown, b: unknown): boolean {
+        // eslint-disable-next-line no-null/no-null
         return a === b || typeof a === "object" && a !== null && typeof b === "object" && b !== null && equalOwnProperties(a as MapLike<unknown>, b as MapLike<unknown>, isJsonEqual);
     }
 

src/harness/collections.ts

@@ -252,7 +252,7 @@ namespace collections {
 
         constructor(parent?: Metadata) {
             this._parent = parent;
-            this._map = Object.create(parent ? parent._map : null);
+            this._map = Object.create(parent ? parent._map : null); // eslint-disable-line no-null/no-null
         }
 
         public get size(): number {
@@ -299,7 +299,7 @@ namespace collections {
         }
 
         public clear(): void {
-            this._map = Object.create(this._parent ? this._parent._map : null);
+            this._map = Object.create(this._parent ? this._parent._map : null); // eslint-disable-line no-null/no-null
             this._size = -1;
             this._version++;
         }

src/harness/harness.ts

@@ -1127,7 +1127,7 @@ namespace Harness {
 
         export function doErrorBaseline(baselinePath: string, inputFiles: ReadonlyArray<TestFile>, errors: ReadonlyArray<ts.Diagnostic>, pretty?: boolean) {
             Baseline.runBaseline(baselinePath.replace(/\.tsx?$/, ".errors.txt"),
-                !errors || (errors.length === 0) ? null : getErrorBaseline(inputFiles, errors, pretty));
+                !errors || (errors.length === 0) ? null : getErrorBaseline(inputFiles, errors, pretty)); // eslint-disable-line no-null/no-null
         }
 
         export function doTypeAndSymbolBaseline(baselinePath: string, program: ts.Program, allFiles: {unitName: string, content: string}[], opts?: Baseline.BaselineOptions, multifile?: boolean, skipTypeBaselines?: boolean, skipSymbolBaselines?: boolean, hasErrorBaseline?: boolean) {
@@ -1205,7 +1205,7 @@ namespace Harness {
                     const [, content] = value;
                     result += content;
                 }
-                return result || null;
+                return result || null; // eslint-disable-line no-null/no-null
             }
 
             function *iterateBaseLine(isSymbolBaseline: boolean, skipBaseline?: boolean): IterableIterator<[string, string]> {
@@ -1276,7 +1276,7 @@ namespace Harness {
                 if ((options.noEmitOnError && result.diagnostics.length !== 0) || result.maps.size === 0) {
                     // We need to return null here or the runBaseLine will actually create a empty file.
                     // Baselining isn't required here because there is no output.
-                    sourceMapCode = null;
+                    sourceMapCode = null; // eslint-disable-line no-null/no-null
                 }
                 else {
                     sourceMapCode = "";
@@ -1338,6 +1338,7 @@ namespace Harness {
                 jsCode += getErrorBaseline(tsConfigFiles.concat(declFileCompilationResult.declInputFiles, declFileCompilationResult.declOtherFiles), declFileCompilationResult.declResult.diagnostics);
             }
 
+            // eslint-disable-next-line no-null/no-null
             Baseline.runBaseline(baselinePath.replace(/\.tsx?/, ts.Extension.Js), jsCode.length > 0 ? tsCode + "\r\n\r\n" + jsCode : null);
         }
 
@@ -1492,7 +1493,7 @@ namespace Harness {
             const opts: CompilerSettings = {};
 
             let match: RegExpExecArray | null;
-            while ((match = optionRegex.exec(content)) !== null) {
+            while ((match = optionRegex.exec(content)) !== null) { // eslint-disable-line no-null/no-null
                 opts[match[1]] = match[2].trim();
             }
 
@@ -1670,6 +1671,7 @@ namespace Harness {
 
             const refFileName = referencePath(relativeFileName, opts && opts.Baselinefolder, opts && opts.Subfolder);
 
+            // eslint-disable-next-line no-null/no-null
             if (actual === null) {
                 actual = noContent;
             }
@@ -1733,6 +1735,8 @@ namespace Harness {
             const gen = generateContent();
             const writtenFiles = ts.createMap<true>();
             const errors: Error[] = [];
+
+            // eslint-disable-next-line no-null/no-null
             if (gen !== null) {
                 for (let {done, value} = gen.next(); !done; { done, value } = gen.next()) {
                     const [name, content, count] = value as [string, string, number | undefined];

src/harness/harnessLanguageService.ts

@@ -1,7 +1,7 @@
 namespace Harness.LanguageService {
 
     export function makeDefaultProxy(info: ts.server.PluginCreateInfo): ts.LanguageService {
-        const proxy = Object.create(/*prototype*/ null);
+        const proxy = Object.create(/*prototype*/ null); // eslint-disable-line no-null/no-null
         const langSvc: any = info.languageService;
         for (const k of Object.keys(langSvc)) {
             // eslint-disable-next-line microsoft-typescript/only-arrow-functions

src/harness/loggedIO.ts

@@ -248,10 +248,10 @@ namespace Playback {
                 const getBase = () => recordLogFileNameBase + i;
                 while (underlying.fileExists(ts.combinePaths(getBase(), "test.json"))) i++;
                 const newLog = oldStyleLogIntoNewStyleLog(recordLog, (path, str) => underlying.writeFile(path, str), getBase());
-                underlying.writeFile(ts.combinePaths(getBase(), "test.json"), JSON.stringify(newLog, null, 4));
+                underlying.writeFile(ts.combinePaths(getBase(), "test.json"), JSON.stringify(newLog, null, 4)); // eslint-disable-line no-null/no-null
                 const syntheticTsconfig = generateTsconfig(newLog);
                 if (syntheticTsconfig) {
-                    underlying.writeFile(ts.combinePaths(getBase(), "tsconfig.json"), JSON.stringify(syntheticTsconfig, null, 4));
+                    underlying.writeFile(ts.combinePaths(getBase(), "tsconfig.json"), JSON.stringify(syntheticTsconfig, null, 4)); // eslint-disable-line no-null/no-null
                 }
                 recordLog = undefined;
             }

src/harness/vfs.ts

@@ -652,7 +652,7 @@ namespace vfs {
          * NOTE: do not rename this method as it is intended to align with the same named export of the "fs" module.
          */
         public readFileSync(path: string, encoding?: string | null): string | Buffer;
-        public readFileSync(path: string, encoding: string | null = null) {
+        public readFileSync(path: string, encoding: string | null = null) { // eslint-disable-line no-null/no-null
             const { node } = this._walk(this._resolve(path));
             if (!node) throw createIOError("ENOENT");
             if (isDirectory(node)) throw createIOError("EISDIR");
@@ -667,6 +667,7 @@ namespace vfs {
          *
          * NOTE: do not rename this method as it is intended to align with the same named export of the "fs" module.
          */
+        // eslint-disable-next-line no-null/no-null
         public writeFileSync(path: string, data: string | Buffer, encoding: string | null = null) {
             if (this.isReadonly) throw createIOError("EROFS");
 
@@ -1114,6 +1115,8 @@ namespace vfs {
                 const value = normalizeFileSetEntry(files[key]);
                 const path = dirname ? vpath.resolve(dirname, key) : key;
                 vpath.validate(path, vpath.ValidationFlags.Absolute);
+
+                // eslint-disable-next-line no-null/no-null
                 if (value === null || value === undefined || value instanceof Rmdir || value instanceof Unlink) {
                     if (this.stringComparer(vpath.dirname(path), path) === 0) {
                         throw new TypeError("Roots cannot be deleted.");
@@ -1508,6 +1511,7 @@ namespace vfs {
         return builtLocalCS;
     }
 
+    /* eslint-disable no-null/no-null */
     function normalizeFileSetEntry(value: FileSet[string]) {
         if (value === undefined ||
             value === null ||
@@ -1522,6 +1526,7 @@ namespace vfs {
         }
         return typeof value === "string" || Buffer.isBuffer(value) ? new File(value) : new Directory(value);
     }
+    /* eslint-enable no-null/no-null */
 
     export function formatPatch(patch: FileSet) {
         return formatPatchWorker("", patch);
@@ -1532,6 +1537,7 @@ namespace vfs {
         for (const name of Object.keys(container)) {
             const entry = normalizeFileSetEntry(container[name]);
             const file = dirname ? vpath.combine(dirname, name) : name;
+            // eslint-disable-next-line no-null/no-null
             if (entry === null || entry === undefined || entry instanceof Unlink || entry instanceof Rmdir) {
                 text += `//// [${file}] unlink\r\n`;
             }

src/services/formatting/formatting.ts

@@ -1197,6 +1197,7 @@ namespace ts.formatting {
             return undefined;
         }
 
+        // eslint-disable-next-line no-null/no-null
         precedingToken = precedingToken === null ? undefined : precedingToken === undefined ? findPrecedingToken(position, sourceFile) : precedingToken;
 
         // Between two consecutive tokens, all comments are either trailing on the former

src/services/formatting/smartIndenter.ts

@@ -34,6 +34,7 @@ namespace ts.formatting {
 
             const precedingToken = findPrecedingToken(position, sourceFile, /*startNode*/ undefined, /*excludeJsdoc*/ true);
 
+            // eslint-disable-next-line no-null/no-null
             const enclosingCommentRange = getRangeOfEnclosingComment(sourceFile, position, precedingToken || null);
             if (enclosingCommentRange && enclosingCommentRange.kind === SyntaxKind.MultiLineCommentTrivia) {
                 return getCommentIndent(sourceFile, position, options, enclosingCommentRange);

src/services/shims.ts

@@ -309,9 +309,11 @@ namespace ts {
         public getChangeRange(oldSnapshot: IScriptSnapshot): TextChangeRange | undefined {
             const oldSnapshotShim = <ScriptSnapshotShimAdapter>oldSnapshot;
             const encoded = this.scriptSnapshotShim.getChangeRange(oldSnapshotShim.scriptSnapshotShim);
+            /* eslint-disable no-null/no-null */
             if (encoded === null) {
                 return null!; // TODO: GH#18217
             }
+            /* eslint-enable no-null/no-null */
 
             const decoded: { span: { start: number; length: number; }; newLength: number; } = JSON.parse(encoded!); // TODO: GH#18217
             return createTextChangeRange(
@@ -396,6 +398,7 @@ namespace ts {
 
         public getCompilationSettings(): CompilerOptions {
             const settingsJson = this.shimHost.getCompilationSettings();
+            // eslint-disable-next-line no-null/no-null
             if (settingsJson === null || settingsJson === "") {
                 throw Error("LanguageServiceShimHostAdapter.getCompilationSettings: empty compilationSettings");
             }
@@ -429,6 +432,7 @@ namespace ts {
         }
 
         public getLocalizedDiagnosticMessages() {
+            /* eslint-disable no-null/no-null */
             const diagnosticMessagesJson = this.shimHost.getLocalizedDiagnosticMessages();
             if (diagnosticMessagesJson === null || diagnosticMessagesJson === "") {
                 return null;
@@ -441,6 +445,7 @@ namespace ts {
                 this.log(e.description || "diagnosticMessages.generated.json has invalid JSON format");
                 return null;
             }
+            /* eslint-enable no-null/no-null */
         }
 
         public getCancellationToken(): HostCancellationToken {
@@ -632,7 +637,7 @@ namespace ts {
         public dispose(dummy: {}): void {
             this.logger.log("dispose()");
             this.languageService.dispose();
-            this.languageService = null!;
+            this.languageService = null!; // eslint-disable-line no-null/no-null
 
             // force a GC
             if (debugObjectHost && debugObjectHost.CollectGarbage) {
@@ -640,7 +645,7 @@ namespace ts {
                 this.logger.log("CollectGarbage()");
             }
 
-            this.logger = null!;
+            this.logger = null!; // eslint-disable-line no-null/no-null
 
             super.dispose(dummy);
         }
@@ -653,7 +658,7 @@ namespace ts {
         public refresh(throwOnError: boolean): void {
             this.forwardJSONCall(
                 `refresh(${throwOnError})`,
-                () => null
+                () => null // eslint-disable-line no-null/no-null
             );
         }
 
@@ -662,7 +667,7 @@ namespace ts {
                 "cleanupSemanticCache()",
                 () => {
                     this.languageService.cleanupSemanticCache();
-                    return null;
+                    return null; // eslint-disable-line no-null/no-null
                 });
         }
 

src/testRunner/compilerRunner.ts

@@ -223,7 +223,7 @@ class CompilerTest {
             const record = utils.removeTestPathPrefixes(this.result.getSourceMapRecord()!);
             const baseline = (this.options.noEmitOnError && this.result.diagnostics.length !== 0) || record === undefined
                 // Because of the noEmitOnError option no files are created. We need to return null because baselining isn't required.
-                ? null
+                ? null // eslint-disable-line no-null/no-null
                 : record;
             Harness.Baseline.runBaseline(this.justName.replace(/\.tsx?$/, ".sourcemap.txt"), baseline);
         }

src/testRunner/externalCompileRunner.ts

@@ -95,6 +95,7 @@ class UserCodeRunner extends ExternalCompileRunnerBase {
         return "user";
     }
     report(result: ExecResult) {
+        // eslint-disable-next-line no-null/no-null
         return result.status === 0 && !result.stdout.length && !result.stderr.length ? null : `Exit Code: ${result.status}
 Standard output:
 ${sortErrors(stripAbsoluteImportPaths(result.stdout.toString().replace(/\r\n/g, "\n")))}
@@ -144,6 +145,7 @@ class DockerfileRunner extends ExternalCompileRunnerBase {
         }
     }
     report(result: ExecResult) {
+        // eslint-disable-next-line no-null/no-null
         return result.status === 0 && !result.stdout.length && !result.stderr.length ? null : `Exit Code: ${result.status}
 Standard output:
 ${sanitizeDockerfileOutput(result.stdout.toString())}
@@ -248,6 +250,8 @@ class DefinitelyTypedRunner extends ExternalCompileRunnerBase {
     report(result: ExecResult, cwd: string) {
         const stdout = removeExpectedErrors(result.stdout.toString(), cwd);
         const stderr = result.stderr.toString();
+
+        // eslint-disable-next-line no-null/no-null
         return !stdout.length && !stderr.length ? null : `Exit Code: ${result.status}
 Standard output:
 ${stdout.replace(/\r\n/g, "\n")}

src/testRunner/parallel/host.ts

@@ -591,6 +591,7 @@ namespace Harness.Parallel.Host {
                 consoleReporter.epilogue();
                 if (noColors) Base.useColors = savedUseColors;
 
+                // eslint-disable-next-line no-null/no-null
                 IO.writeFile(perfdataFileName(configOption), JSON.stringify(newPerfData, null, 4));
 
                 if (xunitReporter) {

src/testRunner/rwcRunner.ts

@@ -155,7 +155,7 @@ namespace RWC {
             it("has the expected declaration file content", () => {
                 Harness.Baseline.runMultifileBaseline(baseName, "", () => {
                     if (!compilerResult.dts.size) {
-                        return null;
+                        return null; // eslint-disable-line no-null/no-null
                     }
 
                     return Harness.Compiler.iterateOutputs(compilerResult.dts.values());
@@ -165,7 +165,7 @@ namespace RWC {
             it("has the expected source maps", () => {
                 Harness.Baseline.runMultifileBaseline(baseName, "", () => {
                     if (!compilerResult.maps.size) {
-                        return null;
+                        return null; // eslint-disable-line no-null/no-null
                     }
 
                     return Harness.Compiler.iterateOutputs(compilerResult.maps.values());
@@ -175,7 +175,7 @@ namespace RWC {
             it("has the expected errors", () => {
                 Harness.Baseline.runMultifileBaseline(baseName, ".errors.txt", () => {
                     if (compilerResult.diagnostics.length === 0) {
-                        return null;
+                        return null; // eslint-disable-line no-null/no-null
                     }
                     // Do not include the library in the baselines to avoid noise
                     const baselineFiles = tsconfigFiles.concat(inputFiles, otherFiles).filter(f => !Harness.isDefaultLibraryFile(f.unitName));
@@ -190,7 +190,7 @@ namespace RWC {
                 if (compilerOptions.declaration && !compilerResult.diagnostics.length) {
                     Harness.Baseline.runMultifileBaseline(baseName, ".dts.errors.txt", () => {
                         if (compilerResult.diagnostics.length === 0) {
-                            return null;
+                            return null; // eslint-disable-line no-null/no-null
                         }
 
                         const declContext = Harness.Compiler.prepareDeclarationCompilationContext(

src/testRunner/test262Runner.ts

@@ -67,6 +67,7 @@ class Test262BaselineRunner extends RunnerBase {
 
             it("has the expected errors", () => {
                 const errors = testState.compilerResult.diagnostics;
+                // eslint-disable-next-line no-null/no-null
                 const baseline = errors.length === 0 ? null : Harness.Compiler.getErrorBaseline(testState.inputFiles, errors);
                 Harness.Baseline.runBaseline(testState.filename + ".errors.txt", baseline, Test262BaselineRunner.baselineOptions);
             });

src/testRunner/unittests/config/configurationExtension.ts

@@ -159,7 +159,7 @@ namespace ts {
                     "dev/configs/third.json": JSON.stringify({
                         extends: "./second",
                         compilerOptions: {
-                            module: null
+                            module: null // eslint-disable-line no-null/no-null
                         },
                         include: ["../supplemental.*"]
                     }),
@@ -168,7 +168,7 @@ namespace ts {
                         compilerOptions: {
                             module: "system"
                         },
-                        include: null,
+                        include: null, // eslint-disable-line no-null/no-null
                         files: ["../main.ts"]
                     }),
                     "dev/configs/fifth.json": JSON.stringify({

src/testRunner/unittests/config/showConfig.ts

@@ -29,6 +29,7 @@ namespace ts {
                     }
                     const initResult = convertToTSConfig(commandLine, configPath, configParseHost);
 
+                    // eslint-disable-next-line no-null/no-null
                     Harness.Baseline.runBaseline(outputFileName, JSON.stringify(initResult, null, 4) + "\n");
                 });
             });

src/testRunner/unittests/moduleResolution.ts

@@ -170,7 +170,7 @@ namespace ts {
             testTypingsIgnored(["a", "b"]);
             testTypingsIgnored({ a: "b" });
             testTypingsIgnored(/*typings*/ true);
-            testTypingsIgnored(/*typings*/ null);
+            testTypingsIgnored(/*typings*/ null); // eslint-disable-line no-null/no-null
             testTypingsIgnored(/*typings*/ undefined);
         });
         it("module name as directory - load index.d.ts", () => {

src/testRunner/unittests/services/transpile.ts

@@ -51,6 +51,7 @@ namespace ts {
                     oldTranspileDiagnostics = undefined!;
                 });
 
+                /* eslint-disable no-null/no-null */
                 it("Correct errors for " + justName, () => {
                     Harness.Baseline.runBaseline(justName.replace(/\.tsx?$/, ".errors.txt"),
                         transpileResult.diagnostics!.length === 0 ? null : Harness.Compiler.getErrorBaseline(toBeCompiled, transpileResult.diagnostics!));
@@ -62,6 +63,7 @@ namespace ts {
                             oldTranspileDiagnostics.length === 0 ? null : Harness.Compiler.getErrorBaseline(toBeCompiled, oldTranspileDiagnostics));
                     });
                 }
+                /* eslint-enable no-null/no-null */
 
                 it("Correct output for " + justName, () => {
                     Harness.Baseline.runBaseline(justName.replace(/\.tsx?$/, Extension.Js), transpileResult.outputText);

src/testRunner/unittests/tsbuild/helpers.ts

@@ -193,6 +193,7 @@ declare const console: { log(msg: any): void; };`;
 
     function generateBaseline(fs: vfs.FileSystem, proj: string, scenario: string, subScenario: string, baseFs: vfs.FileSystem) {
         const patch = fs.diff(baseFs);
+        // eslint-disable-next-line no-null/no-null
         Harness.Baseline.runBaseline(`tsbuild/${proj}/${subScenario.split(" ").join("-")}/${scenario.split(" ").join("-")}.js`, patch ? vfs.formatPatch(patch) : null);
     }
 

src/testRunner/unittests/tsserver/session.ts

@@ -283,7 +283,7 @@ namespace ts.server {
                     session.onMessage(JSON.stringify(req));
                     req.seq = i;
                     i++;
-                    req.arguments = null;
+                    req.arguments = null; // eslint-disable-line no-null/no-null
                     session.onMessage(JSON.stringify(req));
                     req.seq = i;
                     i++;

src/tsc/tsc.ts

@@ -138,6 +138,7 @@ namespace ts {
                     configParseResult.errors.forEach(reportDiagnostic);
                     return sys.exit(ExitStatus.DiagnosticsPresent_OutputsSkipped);
                 }
+                // eslint-disable-next-line no-null/no-null
                 sys.write(JSON.stringify(convertToTSConfig(configParseResult, configFileName, sys), null, 4) + sys.newLine);
                 return sys.exit(ExitStatus.Success);
             }
@@ -155,6 +156,7 @@ namespace ts {
         }
         else {
             if (commandLineOptions.showConfig) {
+                // eslint-disable-next-line no-null/no-null
                 sys.write(JSON.stringify(convertToTSConfig(commandLine, combinePaths(sys.getCurrentDirectory(), "tsconfig.json"), sys), null, 4) + sys.newLine);
                 return sys.exit(ExitStatus.Success);
             }

src/tsserver/server.ts

@@ -198,6 +198,7 @@ namespace ts.server {
         private write(s: string) {
             if (this.fd >= 0) {
                 const buf = sys.bufferFrom!(s);
+                // eslint-disable-next-line no-null/no-null
                 fs.writeSync(this.fd, buf, 0, buf.length, /*position*/ null!); // TODO: GH#18217
             }
             if (this.traceToConsole) {