From a3cbe37aa4ea1711bb7b2cbfc09b0470e842d031 Mon Sep 17 00:00:00 2001
From: Johan Haals <johan.haals@gmail.com>
Date: Thu, 1 Jul 2021 10:02:05 +0200
Subject: [PATCH] backstage-common(GithubUrlReader): Return etag from readUrl,
 add tests

Signed-off-by: Johan Haals <johan.haals@gmail.com>
---
 .../src/reading/GithubUrlReader.test.ts       | 107 ++++++++++++++++++
 .../src/reading/GithubUrlReader.ts            |   8 +-
 2 files changed, 114 insertions(+), 1 deletion(-)

diff --git a/packages/backend-common/src/reading/GithubUrlReader.test.ts b/packages/backend-common/src/reading/GithubUrlReader.test.ts
index 0b3288e59c..c8002cd3ce 100644
--- a/packages/backend-common/src/reading/GithubUrlReader.test.ts
+++ b/packages/backend-common/src/reading/GithubUrlReader.test.ts
@@ -141,6 +141,113 @@ describe('GithubUrlReader', () => {
     });
   });
 
+  /*
+   * readUrl
+   */
+  describe('readUrl', () => {
+    it('should use the headers from the credentials provider to the fetch request when doing readUrl', async () => {
+      expect.assertions(2);
+
+      const mockHeaders = {
+        Authorization: 'bearer blah',
+        otherheader: 'something',
+      };
+
+      (mockCredentialsProvider.getCredentials as jest.Mock).mockResolvedValue({
+        headers: mockHeaders,
+      });
+
+      worker.use(
+        rest.get(
+          'https://ghe.github.com/api/v3/repos/backstage/mock/tree/contents/',
+          (req, res, ctx) => {
+            expect(req.headers.get('authorization')).toBe(
+              mockHeaders.Authorization,
+            );
+            expect(req.headers.get('otherheader')).toBe(
+              mockHeaders.otherheader,
+            );
+            return res(
+              ctx.status(200),
+              ctx.set('Content-Type', 'application/x-gzip'),
+              ctx.body('foo'),
+            );
+          },
+        ),
+      );
+
+      await gheProcessor.readUrl(
+        'https://github.com/backstage/mock/tree/blob/main',
+      );
+    });
+
+    it('should throw NotModified if GitHub responds with 304', async () => {
+      expect.assertions(4);
+
+      const mockHeaders = {
+        Authorization: 'bearer blah',
+        otherheader: 'something',
+      };
+
+      (mockCredentialsProvider.getCredentials as jest.Mock).mockResolvedValue({
+        headers: mockHeaders,
+      });
+
+      worker.use(
+        rest.get(
+          'https://ghe.github.com/api/v3/repos/backstage/mock/tree/contents/',
+          (req, res, ctx) => {
+            expect(req.headers.get('authorization')).toBe(
+              mockHeaders.Authorization,
+            );
+            expect(req.headers.get('otherheader')).toBe(
+              mockHeaders.otherheader,
+            );
+            expect(req.headers.get('if-none-match')).toBe('foo');
+            return res(
+              ctx.status(304),
+              ctx.set('Content-Type', 'application/x-gzip'),
+              ctx.body('foo'),
+            );
+          },
+        ),
+      );
+
+      await expect(
+        gheProcessor.readUrl(
+          'https://github.com/backstage/mock/tree/blob/main',
+          { etag: 'foo' },
+        ),
+      ).rejects.toThrow(NotModifiedError);
+    });
+
+    it('should return etag from the response', async () => {
+      (mockCredentialsProvider.getCredentials as jest.Mock).mockResolvedValue({
+        headers: {
+          Authorization: 'bearer blah',
+        },
+      });
+
+      worker.use(
+        rest.get(
+          'https://ghe.github.com/api/v3/repos/backstage/mock/tree/contents/',
+          (_req, res, ctx) => {
+            return res(
+              ctx.status(200),
+              ctx.set('Etag', 'foo'),
+              ctx.body('bar'),
+            );
+          },
+        ),
+      );
+
+      const response = await gheProcessor.readUrl(
+        'https://github.com/backstage/mock/tree/blob/main',
+      );
+      expect(response.etag).toBe('foo');
+    });
+  });
+
   /*
    * readTree
    */
diff --git a/packages/backend-common/src/reading/GithubUrlReader.ts b/packages/backend-common/src/reading/GithubUrlReader.ts
index 7d12634365..946d863154 100644
--- a/packages/backend-common/src/reading/GithubUrlReader.ts
+++ b/packages/backend-common/src/reading/GithubUrlReader.ts
@@ -109,7 +109,13 @@ export class GithubUrlReader implements UrlReader {
     }
 
     if (response.ok) {
-      return { buffer: async () => Buffer.from(await response.text()) };
+      const etag = response.headers.get('ETag')
+        ? response.headers.get('ETag')!
+        : undefined;
+      return {
+        buffer: async () => Buffer.from(await response.text()),
+        etag,
+      };
     }
 
     const message = `${url} could not be read as ${ghUrl}, ${response.status} ${response.statusText}`;