fix(techdocsStorageClient): properly construct baseUrls

Signed-off-by: Phil Kuang <pkuang@factset.com>

.changeset/techdocs-forty-pumas-compete.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-techdocs': patch
+---
+
+Fix issue where assets weren't being fetched from the correct URL path for doc URLs without trailing slashes

plugins/techdocs/src/client.test.ts

@@ -59,6 +59,12 @@ describe('TechDocsStorageClient', () => {
     ).resolves.toEqual(
       `${mockBaseUrl}/static/docs/${mockEntity.namespace}/${mockEntity.kind}/${mockEntity.name}/test.js`,
     );
+
+    await expect(
+      storageApi.getBaseUrl('../test.js', mockEntity, 'some-docs-path'),
+    ).resolves.toEqual(
+      `${mockBaseUrl}/static/docs/${mockEntity.namespace}/${mockEntity.kind}/${mockEntity.name}/test.js`,
+    );
   });
 
   it('should return base url with correct entity structure', async () => {

plugins/techdocs/src/client.ts

@@ -263,9 +263,11 @@ export class TechDocsStorageClient implements TechDocsStorageApi {
     const { kind, namespace, name } = entityId;
 
     const apiOrigin = await this.getApiOrigin();
+    const newBaseUrl = `${apiOrigin}/static/docs/${namespace}/${kind}/${name}/${path}`;
+
     return new URL(
       oldBaseUrl,
-      `${apiOrigin}/static/docs/${namespace}/${kind}/${name}/${path}`,
+      newBaseUrl.endsWith('/') ? newBaseUrl : `${newBaseUrl}/`,
     ).toString();
   }
 }