add e2e test runner

Author: mayth

README.md

@@ -6,6 +6,7 @@ Simple HTTP server to save artifacts
 - [Usage](#usage)
 - [Authentication](#authentication)
 - [TLS](#tls)
+- [Testing](#testing)
 - [API](#api)
   - [`POST /upload`](#post-upload)
   - [`PUT /files/:path`](#put-filespath)
@@ -78,6 +79,30 @@ v1 has TLS support but I decided to omit it from v2.
 
 Please consider using a reverse proxy like nginx.
 
+## Testing
+
+To run all tests, just run `go test` as usual:
+
+```
+$ go test ./...
+```
+
+This includes end-to-end tests. By default, the server with on-memory FileSystem is created and it starts listening on
+the port chosen randomly. You can control this behavior by setting the environment variables.
+
+If `TEST_WITH_REAL_FS=${PATH_TO_DOCUMENT_ROOT}` is set, the test server uses the real filesystem. Make sure the document
+root directory contains no files; otherwise, some tests might be failed. The directory will not be cleaned after testing.
+
+If `TEST_TARGET_ADDR-${HOST}:${PORT}` is set, the test program doesn't start a local test server and sends requests to
+`http://${HOST}:${PORT}`. Note that the target server's document root should be cleared prior to testing.
+
+This repository has `docker-compose.e2e.yml` to run the E2E test. To run tests using this:
+
+```
+$ docker compose -f docker-compose.e2e.yml run --rm test
+$ docker compose -f docker-compose.e2e.yml down --rmi local --volumes
+```
+
 ## API
 
 ### `POST /upload`

docker-compose.e2e.yml

@@ -0,0 +1,25 @@
+services:
+  app:
+    build:
+      context: .
+      tags:
+        - "mayth/simple-upload-server:testing"
+    ports:
+      - "127.0.0.1::8080"
+    volumes:
+      - docroot:/docroot
+    command: -document_root=/docroot -addr=:8080
+  test:
+    image: golang:1.21
+    environment:
+      - TEST_WITH_REAL_FS=/docroot
+      - TEST_TARGET_ADDR=app:8080
+    volumes:
+      - .:/app
+      - docroot:/docroot
+    working_dir: /app
+    command: go test -v -run TestServer ./...
+    depends_on:
+      - app
+volumes:
+  docroot: