try to resolve includes from nearest tsconfig

Author: christianscott

src/processors/typescript.ts

@@ -111,6 +111,14 @@ export class TypeScriptFileProcessor implements FileProcessor {
       filesList.push(TypeScriptFileProcessor.getEntryPointImport(file));
     }
 
+    const includes = this.includesFromNearestTsconfigFile(file);
+    if (includes.length) {
+      // only include non-globbed includes
+      // TODO: support globbed includes
+      const nonGlobIncludes = includes.filter(maybeGlob => !maybeGlob.includes('*'));
+      filesList.push(...nonGlobIncludes);
+    }
+
     for (const fileName of filesList) {
       const referencedFile = dependencyTree.transformReference(fileName, file);
       if (Array.isArray(referencedFile)) {
@@ -189,6 +197,25 @@ export class TypeScriptFileProcessor implements FileProcessor {
     },
   );
 
+  /**
+   * Finds the tsconfig.json that this file is included by. Does this by searching in the same directory,
+   * and then searching in each dir all the way to the root directory.
+   */
+  private includesFromNearestTsconfigFile = memoize(async (file: Path): Promise<string[]> => {
+    const segments = path.dirname(path.relative(this.rootDir, file)).split(path.sep);
+    while (segments.length > 0) {
+      const maybeTsconfig = path.join(this.rootDir, ...segments, 'tsconfig.json');
+      try {
+        const contents = JSON.parse(await fs.promises.readFile(file, 'utf8'));
+        return 'includes' in contents ? (contents['includes'] as string[]) : [];
+      } catch (err) {
+        segments.pop(); // go up one dir
+        continue;
+      }
+    }
+    throw new Error(`could not find tsconfig.json for ${file}`);
+  });
+
   // Finds an implicit 'import' in the entry point object literal, like:
   //
   //    export const entryPoint: DynamicEntryPoint = {