feat: implements remaining http cache conditionalss (#407)

* implements remaining http conditionals

* computed etag is not optional

tests/cache.rs

@@ -0,0 +1,80 @@
+mod fixtures;
+mod utils;
+
+use chrono::{DateTime, Duration};
+use fixtures::{server, Error, TestServer};
+use reqwest::header::{
+    HeaderName, ETAG, IF_MATCH, IF_MODIFIED_SINCE, IF_NONE_MATCH, IF_UNMODIFIED_SINCE,
+    LAST_MODIFIED,
+};
+use reqwest::StatusCode;
+use rstest::rstest;
+
+#[rstest]
+#[case(IF_UNMODIFIED_SINCE, Duration::days(1), StatusCode::OK)]
+#[case(IF_UNMODIFIED_SINCE, Duration::days(0), StatusCode::OK)]
+#[case(IF_UNMODIFIED_SINCE, Duration::days(-1), StatusCode::PRECONDITION_FAILED)]
+#[case(IF_MODIFIED_SINCE, Duration::days(1), StatusCode::NOT_MODIFIED)]
+#[case(IF_MODIFIED_SINCE, Duration::days(0), StatusCode::NOT_MODIFIED)]
+#[case(IF_MODIFIED_SINCE, Duration::days(-1), StatusCode::OK)]
+fn get_file_with_if_modified_since_condition(
+    #[case] header_condition: HeaderName,
+    #[case] duration_after_file_modified: Duration,
+    #[case] expected_code: StatusCode,
+    server: TestServer,
+) -> Result<(), Error> {
+    let resp = fetch!(b"HEAD", format!("{}index.html", server.url())).send()?;
+
+    let last_modified = resp
+        .headers()
+        .get(LAST_MODIFIED)
+        .and_then(|h| h.to_str().ok())
+        .and_then(|s| DateTime::parse_from_rfc2822(s).ok())
+        .expect("Recieved no valid last modified header");
+
+    let req_modified_time = (last_modified + duration_after_file_modified)
+        .format("%a, %e %b %Y %T GMT")
+        .to_string();
+
+    let resp = fetch!(b"GET", format!("{}index.html", server.url()))
+        .header(header_condition, req_modified_time)
+        .send()?;
+
+    assert_eq!(resp.status(), expected_code);
+    Ok(())
+}
+
+fn same_etag(etag: &str) -> String {
+    etag.to_owned()
+}
+
+fn different_etag(etag: &str) -> String {
+    format!("{}1234", etag)
+}
+
+#[rstest]
+#[case(IF_MATCH, same_etag, StatusCode::OK)]
+#[case(IF_MATCH, different_etag, StatusCode::PRECONDITION_FAILED)]
+#[case(IF_NONE_MATCH, same_etag, StatusCode::NOT_MODIFIED)]
+#[case(IF_NONE_MATCH, different_etag, StatusCode::OK)]
+fn get_file_with_etag_match(
+    #[case] header_condition: HeaderName,
+    #[case] etag_modifier: fn(&str) -> String,
+    #[case] expected_code: StatusCode,
+    server: TestServer,
+) -> Result<(), Error> {
+    let resp = fetch!(b"HEAD", format!("{}index.html", server.url())).send()?;
+
+    let etag = resp
+        .headers()
+        .get(ETAG)
+        .and_then(|h| h.to_str().ok())
+        .expect("Recieved no valid etag header");
+
+    let resp = fetch!(b"GET", format!("{}index.html", server.url()))
+        .header(header_condition, etag_modifier(etag))
+        .send()?;
+
+    assert_eq!(resp.status(), expected_code);
+    Ok(())
+}