feat: consider missing import as dynamic (#14)

Co-authored-by: Julien Ripouteau <[email protected]>

Author: kerwanp

packages/hot_hook/src/dynamic_import_checker.ts

@@ -7,6 +7,8 @@ import { parseImports } from 'parse-imports'
  * Otherwise we will throw an error since we cannot make the file reloadable
  *
  * We are caching the results to avoid reading the same file multiple times
+ *
+ * When no import is found for the given specifier we assume that it is imported using a dynamic specifier.
  */
 export class DynamicImportChecker {
   private cache: Map<string, Map<string, boolean>> = new Map()
@@ -20,10 +22,14 @@ export class DynamicImportChecker {
     const parentCode = await readFile(parentPath, 'utf-8')
     const imports = [...(await parseImports(parentCode))]
 
-    const isFileDynamicallyImportedFromParent = imports.some((importStatement) => {
-      return importStatement.isDynamicImport && importStatement.moduleSpecifier.value === specifier
+    const matchingImport = imports.find((importStatement) => {
+      return importStatement.moduleSpecifier.value === specifier
     })
 
+    const isFileDynamicallyImportedFromParent = matchingImport
+      ? matchingImport.isDynamicImport
+      : true
+
     const currentCache = this.cache.get(cacheKey) ?? new Map()
     this.cache.set(cacheKey, currentCache.set(specifier, isFileDynamicallyImportedFromParent))
 

packages/hot_hook/src/loader.ts

@@ -97,7 +97,15 @@ export class HotHookLoader {
     debug('File change %s', relativeFilePath)
 
     const filePath = pathResolve(relativeFilePath)
-    const realFilePath = await realpath(filePath)
+    const realFilePath = await realpath(filePath).catch(() => null)
+
+    /**
+     * Realpath throws an error when the file does not exist.
+     */
+    if (!realFilePath) {
+      debug('Could not resolve realFilePath %s', filePath)
+      return this.#dependencyTree.remove(filePath)
+    }
 
     /**
      * First check if file still exists. If not, we must remove it from the

packages/hot_hook/tests/dynamic_import_checker.spec.ts

@@ -25,4 +25,19 @@ test.group('Dynamic Import Checker', () => {
     assert.isTrue(await checker.ensureFileIsImportedDynamicallyFromParent(path, './bla'))
     assert.isTrue(await checker.ensureFileIsImportedDynamicallyFromParent(path, '#app/aliases-bla'))
   })
+
+  test('Consider missing specifier as dynamically imported', async ({ assert, fs }) => {
+    await fs.create(
+      'app.ts',
+      `
+        import './foo'
+        await import('./bla')
+      `,
+    )
+
+    const checker = new DynamicImportChecker()
+    const path = join(fs.basePath, 'app.ts')
+
+    assert.isTrue(await checker.ensureFileIsImportedDynamicallyFromParent(path, './unknown'))
+  })
 })