chore(null): switch strictNullChecks config from opt-in to opt-out fo…

…r new files (#6284)

#### Details

This PR updates our strictNullChecks config and tooling to include all
non-test `.ts` and `.tsx` files in the strict null checks set by
default, only excluding those files explicitly marked as having known
issues in `tsconfig.strictNullChecks.json`. This:

* Simplifies the `strictNullChecks` config file a lot (it reduces the
size by half and is now a flat list of files instead of a mix of files
and glob patterns)
* Saves a step of having to manually run `yarn null:autoadd` for most
changes, since new files are now implicitly added
* Removes the corresponding item from our PR checklist (I left the
automated PR check in place since it doesn't hurt anything and has a
self-descriptive error message if it does fail)

To implement this, I wrote a script to perform the conversion from an
include list to an exclude list. I included it for review in this PR,
but I don't expect it to need to be run again in the future. I verified
that `yarn null:progress` reports finding the same counts of checked and
eligible files before and after the change:

> ## Web strict-null progress
> **81%** complete (**1273**/1562 non-test files)
> *Contribute at
[#2869](#2869).
Last update: Tue Dec 20 2022*

I ensured that the assorted helper scripts (`yarn null:find`, `yarn
null:autoadd`, `yarn null:check`) all still work as expected.

##### Motivation

#2869 and see above

##### Context

I considered renaming `autoadd` to something else now that it's arguably
"removing an exclusion" rather than "adding an inclusion", but I decided
to leave it as it; it's still "adding new files to the strict null
checked set" and it felt like more work/confusion than it was worth to
try to update all the issues/team working knowledge/etc about it.

#### Pull request checklist
<!-- If a checklist item is not applicable to this change, write "n/a"
in the checkbox -->
- [x] Addresses an existing issue: #2869
- ~~[x] Ran `yarn null:autoadd`~~
- [x] Ran `yarn fastpass`
- [n/a] Added/updated relevant unit test(s) (and ran `yarn test`)
- [n/a] Verified code coverage for the changes made. Check coverage
report at: `<rootDir>/test-results/unit/coverage`
- [x] PR title *AND* final merge commit title both start with a semantic
tag (`fix:`, `chore:`, `feat(feature-name):`, `refactor:`). See
`CONTRIBUTING.md`.
- [n/a] (UI changes only) Added screenshots/GIFs to description above
- [n/a] (UI changes only) Verified usability with NVDA/JAWS

.github/pull_request_template.md

@@ -15,7 +15,6 @@
 #### Pull request checklist
 <!-- If a checklist item is not applicable to this change, write "n/a" in the checkbox -->
 - [ ] Addresses an existing issue: #0000
-- [ ] Ran `yarn null:autoadd`
 - [ ] Ran `yarn fastpass`
 - [ ] Added/updated relevant unit test(s) (and ran `yarn test`)
 - [ ] Verified code coverage for the changes made. Check coverage report at: `<rootDir>/test-results/unit/coverage`

tools/strict-null-checks/auto-add.js

@@ -5,10 +5,9 @@
 const child_process = require('child_process');
 const fs = require('fs');
 const path = require('path');
-const { collapseCompletedDirectories } = require('./collapse-completed-directories');
 const config = require('./config');
 const { getUncheckedLeafFiles } = require('./eligible-file-finder');
-const { writeTsconfigSync } = require('./write-tsconfig');
+const { writeTsConfig } = require('./write-tsconfig');
 
 const repoRoot = config.repoRoot;
 const tscPath = path.join(repoRoot, 'node_modules', 'typescript', 'bin', 'tsc');
@@ -44,35 +43,30 @@ async function main() {
 
     console.log('## Stopping tsc --watch process...');
     tscWatchProcess.kill();
-
-    console.log('## Collapsing fully null-checked directories into "include" patterns...');
-    collapseCompletedDirectories(tsconfigPath);
 }
 
 async function tryAutoAddStrictNulls(child, tsconfigPath, file) {
     const relativeFilePath = path.relative(repoRoot, file).replace(/\\/g, '/');
     console.log(`Trying to auto add '${relativeFilePath}'`);
 
     const originalConfig = JSON.parse(fs.readFileSync(tsconfigPath).toString());
-    originalConfig.files = Array.from(new Set(originalConfig.files.sort()));
+    originalConfig.exclude = Array.from(new Set(originalConfig.exclude.sort()));
 
     // Config on accept
     const newConfig = Object.assign({}, originalConfig);
-    newConfig.files = Array.from(
-        new Set(originalConfig.files.concat('./' + relativeFilePath).sort()),
-    );
+    newConfig.exclude = originalConfig.exclude.filter(entry => entry !== relativeFilePath);
 
     const buildCompetePromise = waitForBuildComplete(child);
 
-    writeTsconfigSync(tsconfigPath, newConfig);
+    await writeTsConfig(tsconfigPath, newConfig);
 
     const errorCount = await buildCompetePromise;
     const success = errorCount === 0;
     if (success) {
         console.log(`Success`);
     } else {
         console.log(`Errors (x${errorCount}), skipped`);
-        writeTsconfigSync(tsconfigPath, originalConfig);
+        await writeTsConfig(tsconfigPath, originalConfig);
     }
 
     return success;

tools/strict-null-checks/convert-to-exclude.js

@@ -0,0 +1,39 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+// @ts-check
+const fs = require('fs');
+const path = require('path');
+const config = require('./config');
+const { getAllCheckedFiles, getAllEligibleFiles } = require('./eligible-file-finder');
+const { writeTsConfig } = require('./write-tsconfig');
+
+const repoRoot = config.repoRoot;
+const tsconfigPath = path.join(repoRoot, config.targetTsconfig);
+
+async function main() {
+    const excludeList = await buildExcludeList();
+    const tsconfig = JSON.parse(fs.readFileSync(tsconfigPath).toString());
+
+    delete tsconfig.files;
+    tsconfig.include = ['src/**/*.ts', 'src/**/*.tsx'];
+    tsconfig.exclude = ['**/*.test.ts', '**/*.test.tsx', ...excludeList];
+
+    await writeTsConfig(tsconfigPath, tsconfig);
+}
+
+async function buildExcludeList() {
+    const checkedFiles = await getAllCheckedFiles();
+    const eligibleFiles = await getAllEligibleFiles();
+
+    const allUncheckedFiles = eligibleFiles.filter(file => !checkedFiles.has(file));
+
+    allUncheckedFiles.sort();
+
+    return allUncheckedFiles.map(file => path.relative(repoRoot, file).replace(/\\/g, '/'));
+}
+
+main().catch(error => {
+    console.error(error.stack);
+    process.exit(1);
+});

tools/strict-null-checks/eligible-file-finder.js

@@ -45,17 +45,26 @@ async function getAllCheckedFiles() {
     const tsconfigContent = JSON.parse(fs.readFileSync(tsconfigPath).toString());
 
     const set = new Set(
-        tsconfigContent.files.map(f => path.join(config.repoRoot, f).replace(/\\/g, '/')),
+        (tsconfigContent.files ?? []).map(f => path.join(config.repoRoot, f).replace(/\\/g, '/')),
     );
     await Promise.all(
-        tsconfigContent.include.map(async include => {
+        (tsconfigContent.include ?? []).map(async include => {
             const includePath = path.join(config.repoRoot, include);
             const files = await globAsync(includePath);
             for (const file of files) {
                 set.add(file);
             }
         }),
     );
+    await Promise.all(
+        (tsconfigContent.exclude ?? []).map(async exclude => {
+            const excludePath = path.join(config.repoRoot, exclude);
+            const files = await globAsync(excludePath);
+            for (const file of files) {
+                set.delete(file);
+            }
+        }),
+    );
     return set;
 }
 

tools/strict-null-checks/write-tsconfig.js

@@ -1,12 +1,20 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
 const fs = require('fs');
+const path = require('path');
+const prettier = require('prettier');
 
 module.exports = {
-    writeTsconfigSync: (tsconfigPath, content) => {
+    writeTsConfig: async (tsconfigPath, content) => {
         let serializedContent = JSON.stringify(content, null, '    ');
-        serializedContent += '\n';
 
-        fs.writeFileSync(tsconfigPath, serializedContent);
+        let prettierConfigPath = path.join(__dirname, '..', '..', 'prettier.config.js');
+        let prettierConfig = await prettier.resolveConfig(prettierConfigPath);
+        let formattedContent = prettier.format(serializedContent, {
+            ...prettierConfig,
+            filepath: tsconfigPath,
+        });
+
+        fs.writeFileSync(tsconfigPath, formattedContent);
     },
 };