SC-4931: add E2E test against real binary

.github/workflows/ci.yml

@@ -17,4 +17,13 @@ jobs:
 
       - run: go vet ./...
 
-      - run: go test -race ./...
+      - name: Run unit tests
+        run: go test -race ./...
+
+      - name: Run E2E tests with binary
+        run: go test -tags e2e -count=1 ./test/e2e/...
+
+      - name: Run E2E tests with Docker image
+        run: go test -tags e2e -count=1 ./test/e2e/...
+        env:
+          E2E_DOCKER: "1"

README.md

@@ -155,3 +155,19 @@ On shutdown (SIGINT/SIGTERM), the stream is deleted from the transmitter before
 go test ./...
 go vet ./...
 ```
+
+### E2E tests
+
+The end-to-end tests in `test/e2e/` run the real compiled binary against an in-process fake transmitter and webhook sink. They are excluded from `go test ./...` by a build tag and must be run explicitly:
+
+```sh
+go test -tags e2e -count 1 ./test/e2e/...
+```
+
+The test builds the binary from source automatically — no extra setup required.
+
+You can also run the E2E tests against the built Docker image. This requires host networking, so it will only work on Linux:
+
+```sh
+E2E_DOCKER=1 go test -tags e2e -count 1 ./test/e2e/...
+```