fix(rosetta): 'extract' does not translate samples in submodule READM…

…Es (#2744)

Now that the CDK release branch contains the ubergen [fix](aws/aws-cdk@e047bda) that aligns rosseta fixtures, we can try and re-introduce this fix. 

---

By submitting this pull request, I confirm that my contribution is made under the terms of the [Apache 2.0 license].

[Apache 2.0 license]: https://www.apache.org/licenses/LICENSE-2.0

packages/jsii-rosetta/lib/jsii/assemblies.ts

@@ -68,6 +68,18 @@ export function allSnippetSources(
  });
  }
 
+ for (const [submoduleFqn, submodule] of Object.entries(
+ assembly.submodules ?? {},
+ )) {
+ if (submodule.readme) {
+ ret.push({
+ type: 'markdown',
+ markdown: submodule.readme.markdown,
+ where: removeSlashes(`${submoduleFqn}-README`),
+ });
+ }
+ }
+
  if (assembly.types) {
  Object.values(assembly.types).forEach((type) => {
  emitDocs(type.docs, `${assembly.name}.${type.name}`);

packages/jsii-rosetta/test/jsii/assemblies.test.ts

@@ -29,6 +29,33 @@ test('Extract snippet from README', () => {
  expect(snippets[0].visibleSource).toEqual('someExample();');
 });
 
+test('Extract snippet from submodule READMEs', () => {
+ const snippets = Array.from(
+ allTypeScriptSnippets([
+ {
+ assembly: fakeAssembly({
+ submodules: {
+ 'my.submodule': {
+ readme: {
+ markdown: [
+ 'Before the example.',
+ '```ts',
+ 'someExample();',
+ '```',
+ 'After the example.',
+ ].join('\n'),
+ },
+ },
+ },
+ }),
+ directory: path.join(__dirname, 'fixtures'),
+ },
+ ]),
+ );
+
+ expect(snippets[0].visibleSource).toEqual('someExample();');
+});
+
 test('Extract snippet from type docstring', () => {
  const snippets = Array.from(
  allTypeScriptSnippets([