Add automated tests to verify curl's TLS signature

Add automated testing infrastructure with tests verifying that
`curl-impersonate` has the same TLS signature as that of the
impersonated browser.

Each wrapper script (e.g. curl_chrome98) is launched to wikipedia.org
while a packet capture is running in the background. The Client Hello
is extracted from the capture, parsed and then compared to the known
browser signature.

The known signatures are stored in a YAML database.

tests/README.md

@@ -0,0 +1,24 @@
+The tests verify that `curl-impersonate` has the same network signature as that of the supported browsers. They do not test curl's functionality itself.
+
+## Running the tests
+
+The tests assume that you've built both `curl-impersonate-chrome` and `curl-impersonate-ff` docker images before (see [Installation](https://github.com/lwthiker/curl-impersonate#installation)).
+
+To run the tests, build with:
+```
+docker build -t curl-impersonate-tests tests/
+```
+then run with:
+```
+docker run --rm curl-impersonate-tests
+```
+This simply runs `pytest` in the container. You can pass additional flags to `pytest` such as `--log-cli-level DEBUG`.
+
+## How the tests work
+For each supported browser, a packet capture is started while `curl-impersonate` is run with the relevant wrapper script. The Client Hello message is extracted from the capture, and compared against the known signature of the browser.
+
+## What's missing
+The following tests are still missing:
+* Test that `curl-impersonate` sends the HTTP headers in the same order as the browser.
+* Test that `curl-impersonate` sends the HTTP/2 pseudo-headers in the same order as the browser.
+* Test that `curl-impersonate` sends the same HTTP/2 SETTINGS as the browser.