Remove many uses of 'null' in harness

src/harness/compilerRunner.ts

@@ -1,6 +1,7 @@
 /// <reference path="harness.ts" />
 /// <reference path="runnerbase.ts" />
 /// <reference path="typeWriter.ts" />
+// In harness baselines, null is different than undefined. See `generateActual` in `harness.ts`.
 /* tslint:disable:no-null-keyword */
 
 const enum CompilerTestType {

src/harness/external/chai.d.ts

@@ -169,7 +169,6 @@ declare module chai {
         function notEqual(actual: any, expected: any, message?: string): void;
         function isTrue(value: any, message?: string): void;
         function isFalse(value: any, message?: string): void;
-        function isNull(value: any, message?: string): void;
-        function isNotNull(value: any, message?: string): void;
+        function isOk(actual: any, message?: string): void;
     }
 }

src/harness/fourslash.ts

@@ -18,7 +18,6 @@
 /// <reference path="harnessLanguageService.ts" />
 /// <reference path="harness.ts" />
 /// <reference path="fourslashRunner.ts" />
-/* tslint:disable:no-null-keyword */
 
 namespace FourSlash {
     ts.disableIncrementalParsing = false;
@@ -198,7 +197,7 @@ namespace FourSlash {
         public lastKnownMarker: string = "";
 
         // The file that's currently 'opened'
-        public activeFile: FourSlashFile = null;
+        public activeFile: FourSlashFile;
 
         // Whether or not we should format on keystrokes
         public enableFormatting = true;
@@ -922,7 +921,7 @@ namespace FourSlash {
 
         public verifyCurrentParameterIsletiable(isVariable: boolean) {
             const signature = this.getActiveSignatureHelpItem();
-            assert.isNotNull(signature);
+            assert.isOk(signature);
             assert.equal(isVariable, signature.isVariadic);
         }
 
@@ -1911,7 +1910,7 @@ namespace FourSlash {
         public verifyNavigationItemsCount(expected: number, searchValue: string, matchKind?: string) {
             const items = this.languageService.getNavigateToItems(searchValue);
             let actual = 0;
-            let item: ts.NavigateToItem = null;
+            let item: ts.NavigateToItem;
 
             // Count only the match that match the same MatchKind
             for (let i = 0; i < items.length; i++) {
@@ -2183,7 +2182,7 @@ namespace FourSlash {
         }
 
         private findFile(indexOrName: any) {
-            let result: FourSlashFile = null;
+            let result: FourSlashFile;
             if (typeof indexOrName === "number") {
                 const index = <number>indexOrName;
                 if (index >= this.testData.files.length) {
@@ -2352,10 +2351,16 @@ ${code}
         const ranges: Range[] = [];
 
         // Stuff related to the subfile we're parsing
-        let currentFileContent: string = null;
+        let currentFileContent: string = undefined;
         let currentFileName = fileName;
         let currentFileOptions: { [s: string]: string } = {};
 
+        function resetLocalData() {
+            currentFileContent = undefined;
+            currentFileOptions = {};
+            currentFileName = fileName;
+        }
+
         for (let i = 0; i < lines.length; i++) {
             let line = lines[i];
             const lineLength = line.length;
@@ -2368,7 +2373,7 @@ ${code}
                 // Subfile content line
 
                 // Append to the current subfile content, inserting a newline needed
-                if (currentFileContent === null) {
+                if (currentFileContent === undefined) {
                     currentFileContent = "";
                 }
                 else {
@@ -2400,10 +2405,7 @@ ${code}
                                 // Store result file
                                 files.push(file);
 
-                                // Reset local data
-                                currentFileContent = null;
-                                currentFileOptions = {};
-                                currentFileName = fileName;
+                                resetLocalData();
                             }
 
                             currentFileName = basePath + "/" + match[2];
@@ -2430,10 +2432,7 @@ ${code}
                     // Store result file
                     files.push(file);
 
-                    // Reset local data
-                    currentFileContent = null;
-                    currentFileOptions = {};
-                    currentFileName = fileName;
+                    resetLocalData();
                 }
             }
         }
@@ -2498,7 +2497,7 @@ ${code}
 
         if (markerValue === undefined) {
             reportError(fileName, location.sourceLine, location.sourceColumn, "Object markers can not be empty");
-            return null;
+            return undefined;
         }
 
         const marker: Marker = {
@@ -2527,7 +2526,7 @@ ${code}
         if (markerMap[name] !== undefined) {
             const message = "Marker '" + name + "' is duplicated in the source file contents.";
             reportError(marker.fileName, location.sourceLine, location.sourceColumn, message);
-            return null;
+            return undefined;
         }
         else {
             markerMap[name] = marker;
@@ -2546,7 +2545,7 @@ ${code}
         let output = "";
 
         /// The current marker (or maybe multi-line comment?) we're parsing, possibly
-        let openMarker: LocationInformation = null;
+        let openMarker: LocationInformation = undefined;
 
         /// A stack of the open range markers that are still unclosed
         const openRanges: RangeLocationInformation[] = [];
@@ -2654,7 +2653,7 @@ ${code}
                             difference += i + 1 - openMarker.sourcePosition;
 
                             // Reset the state
-                            openMarker = null;
+                            openMarker = undefined;
                             state = State.none;
                         }
                         break;
@@ -2676,7 +2675,7 @@ ${code}
                             difference += i + 1 - openMarker.sourcePosition;
 
                             // Reset the state
-                            openMarker = null;
+                            openMarker = undefined;
                             state = State.none;
                         }
                         else if (validMarkerChars.indexOf(currentChar) < 0) {
@@ -2688,7 +2687,7 @@ ${code}
                                 // Bail out the text we've gathered so far back into the output
                                 flush(i);
                                 lastNormalCharPosition = i;
-                                openMarker = null;
+                                openMarker = undefined;
 
                                 state = State.none;
                             }
@@ -2719,7 +2718,7 @@ ${code}
             reportError(fileName, openRange.sourceLine, openRange.sourceColumn, "Unterminated range.");
         }
 
-        if (openMarker !== null) {
+        if (openMarker) {
             reportError(fileName, openMarker.sourceLine, openMarker.sourceColumn, "Unterminated marker.");
         }
 

src/harness/fourslashRunner.ts

@@ -1,7 +1,6 @@
 ///<reference path="fourslash.ts" />
 ///<reference path="harness.ts"/>
 ///<reference path="runnerbase.ts" />
-/* tslint:disable:no-null-keyword */
 
 const enum FourSlashTestType {
     Native,

src/harness/harness.ts

@@ -23,7 +23,6 @@
 /// <reference path="external\chai.d.ts"/>
 /// <reference path="sourceMapRecorder.ts"/>
 /// <reference path="runnerbase.ts"/>
-/* tslint:disable:no-null-keyword */
 
 // Block scoped definitions work poorly for global variables, temporarily enable var
 /* tslint:disable:no-var-keyword */
@@ -32,7 +31,7 @@
 var _chai: typeof chai = require("chai");
 var assert: typeof _chai.assert = _chai.assert;
 declare var __dirname: string; // Node-specific
-var global = <any>Function("return this").call(null);
+var global = <any>Function("return this").call(undefined);
 /* tslint:enable:no-var-keyword */
 
 namespace Utils {
@@ -558,15 +557,9 @@ namespace Harness {
             }
 
             export function directoryName(path: string) {
-                let dirPath = pathModule.dirname(path);
-
+                const dirPath = pathModule.dirname(path);
                 // Node will just continue to repeat the root path, rather than return null
-                if (dirPath === path) {
-                    dirPath = null;
-                }
-                else {
-                    return dirPath;
-                }
+                return dirPath === path ? undefined : dirPath;
             }
 
             export let listFiles: typeof IO.listFiles = (path, spec?, options?) => {
@@ -634,7 +627,7 @@ namespace Harness {
                         xhr.send();
                     }
                     catch (e) {
-                        return { status: 404, responseText: null };
+                        return { status: 404, responseText: undefined };
                     }
 
                     return waitForXHR(xhr);
@@ -651,7 +644,7 @@ namespace Harness {
                     }
                     catch (e) {
                         log(`XHR Error: ${e}`);
-                        return { status: 500, responseText: null };
+                        return { status: 500, responseText: undefined };
                     }
 
                     return waitForXHR(xhr);
@@ -663,7 +656,7 @@ namespace Harness {
             }
 
             export function deleteFile(path: string) {
-                Http.writeToServerSync(serverRoot + path, "DELETE", null);
+                Http.writeToServerSync(serverRoot + path, "DELETE");
             }
 
             export function directoryExists(path: string): boolean {
@@ -674,7 +667,7 @@ namespace Harness {
                 let dirPath = path;
                 // root of the server
                 if (dirPath.match(/localhost:\d+$/) || dirPath.match(/localhost:\d+\/$/)) {
-                    dirPath = null;
+                    dirPath = undefined;
                     // path + fileName
                 }
                 else if (dirPath.indexOf(".") === -1) {
@@ -722,7 +715,7 @@ namespace Harness {
                     return response.responseText;
                 }
                 else {
-                    return null;
+                    return undefined;
                 }
             }
 
@@ -1418,7 +1411,9 @@ namespace Harness {
             const opts: CompilerSettings = {};
 
             let match: RegExpExecArray;
-            while ((match = optionRegex.exec(content)) != null) {
+            /* tslint:disable:no-null-keyword */
+            while ((match = optionRegex.exec(content)) !== null) {
+            /* tslint:enable:no-null-keyword */
                 opts[match[1]] = match[2];
             }
 
@@ -1435,9 +1430,9 @@ namespace Harness {
             const lines = Utils.splitContentByNewlines(code);
 
             // Stuff related to the subfile we're parsing
-            let currentFileContent: string = null;
+            let currentFileContent: string = undefined;
             let currentFileOptions: any = {};
-            let currentFileName: any = null;
+            let currentFileName: any = undefined;
             let refs: string[] = [];
 
             for (let i = 0; i < lines.length; i++) {
@@ -1465,7 +1460,7 @@ namespace Harness {
                         testUnitData.push(newTestFile);
 
                         // Reset local data
-                        currentFileContent = null;
+                        currentFileContent = undefined;
                         currentFileOptions = {};
                         currentFileName = testMetaData[2];
                         refs = [];
@@ -1478,7 +1473,7 @@ namespace Harness {
                 else {
                     // Subfile content line
                     // Append to the current subfile content, inserting a newline needed
-                    if (currentFileContent === null) {
+                    if (currentFileContent === undefined) {
                         currentFileContent = "";
                     }
                     else {
@@ -1601,7 +1596,9 @@ namespace Harness {
 
             // Store the content in the 'local' folder so we
             // can accept it later (manually)
+            /* tslint:disable:no-null-keyword */
             if (actual !== null) {
+            /* tslint:enable:no-null-keyword */
                 IO.writeFile(actualFileName, actual);
             }
 
@@ -1618,7 +1615,9 @@ namespace Harness {
 
             const refFileName = referencePath(relativeFileName, opts && opts.Baselinefolder, opts && opts.Subfolder);
 
+            /* tslint:disable:no-null-keyword */
             if (actual === null) {
+            /* tslint:enable:no-null-keyword */
                 actual = "<no content>";
             }
 

src/harness/harnessLanguageService.ts

@@ -172,7 +172,7 @@ namespace Harness.LanguageService {
           */
         public positionToLineAndCharacter(fileName: string, position: number): ts.LineAndCharacter {
             const script: ScriptInfo = this.fileNameToScript[fileName];
-            assert.isNotNull(script);
+            assert.isOk(script);
 
             return ts.computeLineAndCharacterOfPosition(script.getLineMap(), position);
         }

src/harness/loggedIO.ts

@@ -1,7 +1,6 @@
 /// <reference path="..\..\src\compiler\sys.ts" />
 /// <reference path="..\..\src\harness\harness.ts" />
 /// <reference path="..\..\src\harness\runnerbase.ts" />
-/* tslint:disable:no-null-keyword */
 
 interface FileInformation {
     contents: string;
@@ -94,7 +93,7 @@ namespace Playback {
             return lookup[s] = func(s);
         });
         run.reset = () => {
-            lookup = null;
+            lookup = undefined;
         };
 
         return run;
@@ -170,7 +169,8 @@ namespace Playback {
             path => callAndRecord(underlying.fileExists(path), recordLog.fileExists, { path }),
             memoize(path => {
                 // If we read from the file, it must exist
-                if (findResultByPath(wrapper, replayLog.filesRead, path, null) !== null) {
+                const noResult = {};
+                if (findResultByPath(wrapper, replayLog.filesRead, path, noResult) !== noResult) {
                     return true;
                 }
                 else {

src/harness/projectsRunner.ts

@@ -1,6 +1,5 @@
 ///<reference path="harness.ts" />
 ///<reference path="runnerbase.ts" />
-/* tslint:disable:no-null-keyword */
 
 // Test case is json of below type in tests/cases/project/
 interface ProjectRunnerTestCase {
@@ -53,7 +52,7 @@ class ProjectRunner extends RunnerBase {
     private runProjectTestCase(testCaseFileName: string) {
         let testCase: ProjectRunnerTestCase & ts.CompilerOptions;
 
-        let testFileText: string = null;
+        let testFileText: string;
         try {
             testFileText = Harness.IO.readFile(testCaseFileName);
         }

src/harness/runner.ts

@@ -20,8 +20,6 @@
 /// <reference path="rwcRunner.ts" />
 /// <reference path="harness.ts" />
 
-/* tslint:disable:no-null-keyword */
-
 let runners: RunnerBase[] = [];
 let iterations = 1;