Handle source file / source map fetch errors correctly, add tests (#41342)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/41342

While rewriting `Debugger.getScriptSource` messages to fetch code and source map over HTTP, we weren't checking the status code of the fetch calls. This diff fixes that and adds corresponding tests (as well as for the filesystem error case).

Changelog: [Internal]

Reviewed By: robhogan

Differential Revision: D51013054

fbshipit-source-id: 58e7bb9fcd6a3cf92329b43fb8a139093c80d305

packages/dev-middleware/src/__tests__/InspectorProxyCdpRewritingHacks-test.js

@@ -89,6 +89,57 @@ describe.each(['HTTP', 'HTTPS'])(
       }
     });
 
+    test('handling of failure to fetch source map', async () => {
+      const {device, debugger_} = await createAndConnectTarget(
+        serverRef,
+        autoCleanup.signal,
+        {
+          app: 'bar-app',
+          id: 'page1',
+          title: 'bar-title',
+          vm: 'bar-vm',
+        },
+      );
+      try {
+        const scriptParsedMessage = await sendFromTargetToDebugger(
+          device,
+          debugger_,
+          'page1',
+          {
+            method: 'Debugger.scriptParsed',
+            params: {
+              sourceMapURL: `${serverRef.serverBaseUrl}/source-map-missing`,
+            },
+          },
+        );
+
+        // We don't rewrite the message in this case.
+        expect(scriptParsedMessage.params.sourceMapURL).toEqual(
+          `${serverRef.serverBaseUrl}/source-map-missing`,
+        );
+
+        // We send an error through to the debugger as a console message.
+        expect(debugger_.handle).toBeCalledWith(
+          expect.objectContaining({
+            method: 'Runtime.consoleAPICalled',
+            params: {
+              args: [
+                {
+                  type: 'string',
+                  value: expect.stringMatching('Failed to fetch source map'),
+                },
+              ],
+              executionContextId: 0,
+              type: 'error',
+            },
+          }),
+        );
+      } finally {
+        device.close();
+        debugger_.close();
+      }
+    });
+
     describe.each(['10.0.2.2', '10.0.3.2'])(
       '%s aliasing to and from localhost',
       sourceHost => {
@@ -326,6 +377,89 @@ describe.each(['HTTP', 'HTTPS'])(
           debugger_.close();
         }
       });
+
+      test.each(['url', 'file'])(
+        'reports %s fetch error back to debugger',
+        async resourceType => {
+          const {device, debugger_} = await createAndConnectTarget(
+            serverRef,
+            autoCleanup.signal,
+            {
+              app: 'bar-app',
+              id: 'page1',
+              title: 'bar-title',
+              vm: 'bar-vm',
+            },
+          );
+          try {
+            await sendFromTargetToDebugger(device, debugger_, 'page1', {
+              method: 'Debugger.scriptParsed',
+              params: {
+                scriptId: 'script1',
+                url:
+                  resourceType === 'url'
+                    ? `${serverRef.serverBaseUrl}/source-missing`
+                    : '__fixtures__/mock-source-file.does-not-exist',
+                startLine: 0,
+                endLine: 0,
+                startColumn: 0,
+                endColumn: 0,
+                hash: createHash('sha256').update('foo').digest('hex'),
+              },
+            });
+            const response = await debugger_.sendAndGetResponse({
+              id: 1,
+              method: 'Debugger.getScriptSource',
+              params: {
+                scriptId: 'script1',
+              },
+            });
+
+            // We mark the request as failed.
+            expect(response).toEqual({
+              id: 1,
+              result: {
+                error: {
+                  message: expect.stringMatching(
+                    `Failed to fetch source ${resourceType}`,
+                  ),
+                },
+              },
+            });
+
+            // We also send an error through to the debugger as a console message.
+            expect(debugger_.handle).toBeCalledWith(
+              expect.objectContaining({
+                method: 'Runtime.consoleAPICalled',
+                params: {
+                  args: [
+                    {
+                      type: 'string',
+                      value: expect.stringMatching(
+                        `Failed to fetch source ${resourceType}`,
+                      ),
+                    },
+                  ],
+                  executionContextId: 0,
+                  type: 'error',
+                },
+              }),
+            );
+
+            // The device does not receive the getScriptSource request, since it
+            // is handled by the proxy.
+            expect(device.wrappedEventParsed).not.toBeCalledWith({
+              pageId: 'page1',
+              wrappedEvent: expect.objectContaining({
+                method: 'Debugger.getScriptSource',
+              }),
+            });
+          } finally {
+            device.close();
+            debugger_.close();
+          }
+        },
+      );
     });
   },
 );

packages/dev-middleware/src/inspector-proxy/Device.js

@@ -680,6 +680,9 @@ export default class Device {
 
     // $FlowFixMe[incompatible-call] Suppress arvr node-fetch flow error
     const response = await fetch(url);
+    if (!response.ok) {
+      throw new Error('HTTP ' + response.status + ' ' + response.statusText);
+    }
     const text = await response.text();
     // Restrict the length to well below the 500MB limit for nodejs (leaving
     // room some some later manipulation, e.g. base64 or wrapping in JSON)