Add tests, use prettier, and add a workaround for comments-need-a-sta…

…tement constraint

scripts/www/rewriteImports.js

@@ -12,61 +12,7 @@ const fs = require('fs-extra');
 const glob = require('glob');
 const path = require('node:path');
 const {packagesManager} = require('../shared/packagesManager');
-const npmToWwwName = require('./npmToWwwName');
-const {t, transform} = require('hermes-transform');
-
-const wwwMappings = Object.fromEntries(
-  packagesManager
-    .getPublicPackages()
-    .flatMap((pkg) =>
-      pkg.getExportedNpmModuleNames().map((npm) => [npm, npmToWwwName(npm)]),
-    ),
-);
-
-/**
- * It would be nice to use jscodeshift for this but the flow sources are using
- * ast features that are not supported in ast-types (as of 2024-04-11) so it's
- * not possible to traverse the tree and replace the imports & comments.
- *
- * It might be possible going straight to flow-parser, but it was a slew of
- * hardcoded regexps before and now it's at least automated based on the
- * exports.
- *
- * @param {string} source
- * @returns {Promise<string>} transformed source
- */
-async function transformFlowFileContents(source) {
-  return await transform(
-    source,
-    (context) => ({
-      ImportDeclaration(node) {
-        const value = wwwMappings[node.source.value];
-        if (value) {
-          context.replaceNode(node.source, t.StringLiteral({value}));
-        }
-      },
-      Program(node) {
-        if (
-          node.docblock &&
-          node.docblock.comment &&
-          node.docblock.comment.value.includes('@flow strict')
-        ) {
-          // This is mutated in-place because I couldn't find a mutation that
-          // did not fail for replacing the Program node.
-          node.docblock.comment.value = node.docblock.comment.value.replace(
-            / \* @flow strict/g,
-            ' * @flow strict\n * @generated\n * @oncall lexical_web_text_editor',
-          );
-          // We need the mutations array to be non-empty, so remove something
-          // that is not there. The AST traversals use object identity in a
-          // Set so we don't have to worry about some other line changing.
-          context.removeComments(t.LineComment({value: ''}));
-        }
-      },
-    }),
-    {},
-  );
-}
+const transformFlowFileContents = require('./transformFlowFileContents');
 
 // This script attempts to find all Flow definition modules, and makes
 // them compatible with www. Specifically, it finds any imports that