Add high-level expectations

[PiotrSikora]

Provide high-level expectations, e.g.:

http_headers_test
    .http_request(vec![
            (":method", "GET"),
            (":path", "/hello"),
            (":authority", "developer"),
        ],
        None, // request body
        None, // request trailers
    )
    .expect_log(LogLevel::Trace, "#1 -> :method: GET")
    .expect_log(LogLevel::Trace, "#1 -> :path: /hello")
    .expect_log(LogLevel::Trace, "#1 -> :authority: developer")
    .execute_and_expect(ReturnType::Action(Action::Continue))?;

which would be more or less equivalent to this test expressed using currently available low-level expectations:

http_headers_test
    .call_start()
    .execute_and_expect(ReturnType::None)?;

let root_context = 1;
http_headers_test
    .call_proxy_on_context_create(root_context, 0)
    .execute_and_expect(ReturnType::None)?;

let http_context = 2;
http_headers_test
    .call_proxy_on_context_create(http_context, root_context)
    .execute_and_expect(ReturnType::None)?;

http_headers_test
    .call_proxy_on_request_headers(http_context, 0)
    .expect_get_header_map_pairs(MapType::HttpRequestHeaders)
    .returning(vec![
        (":method", "GET"),
            (":path", "/hello"),
            (":authority", "developer"),
        ])
    .expect_log(LogLevel::Trace, "#1 -> :method: GET")
    .expect_log(LogLevel::Trace, "#1 -> :path: /hello")
    .expect_log(LogLevel::Trace, "#1 -> :authority: developer")
    .execute_and_expect(ReturnType::Action(Action::Continue))?;

[PiotrSikora]

cc @agiachris

[agiachris]

Yes, this is on the TODO for next week.