gatewayd: config, [approvals] users and socket

Implemented-By: OpenCode session (model recorded in docs/implementer-log.md)

crates/gatewayd/tests/config_approvals.rs

@@ -0,0 +1,68 @@
+//! `[approvals]` in `gatewayd.toml`: who may answer, the first approver, and `gateway.sock`
+//! (M4b spec, section 3). Do not edit.
+
+use std::path::PathBuf;
+
+use gatewayd::config::Config;
+
+const KYLE: &str = "k0000000000000000000000000";
+const HERMES: &str = "h0000000000000000000000000";
+const OTHER: &str = "o0000000000000000000000000";
+
+fn text(approvals: &str) -> String {
+    format!(
+        "[mattermost]\nurl = \"https://chat.example\"\n[secrets.mattermost_token]\nenv = \"T\"\n[allow]\nusers = [\"{KYLE}\", \"{HERMES}\"]\n[paths]\nhome = \"/srv/bx\"\n{approvals}"
+    )
+}
+
+fn config(approvals: &str) -> Config {
+    let c = Config::parse(&text(approvals)).unwrap();
+    assert_eq!(c.problem(), None);
+    c
+}
+
+#[test]
+fn without_the_section_everyone_allowed_may_answer() {
+    let c = config("");
+    assert_eq!(c.approvers(), [KYLE, HERMES]);
+    assert_eq!(c.first_approver(), Some(KYLE));
+    assert_eq!(
+        c.gateway_socket(),
+        PathBuf::from("/srv/bx/run/gateway/gateway.sock")
+    );
+    assert_eq!(
+        config("[approvals]\nusers = []\n").approvers(),
+        [KYLE, HERMES]
+    );
+}
+
+#[test]
+fn a_list_narrows_who_may_answer() {
+    let c = config(&format!(
+        "[approvals]\nusers = [\"{HERMES}\"]\nsocket = \"/run/gw.sock\"\n"
+    ));
+    assert_eq!(c.approvers(), [HERMES]);
+    assert_eq!(c.first_approver(), Some(HERMES));
+    assert_eq!(c.gateway_socket(), PathBuf::from("/run/gw.sock"));
+}
+
+#[test]
+fn an_approver_must_be_heard() {
+    let c = Config::parse(&text(&format!(
+        "[approvals]\nusers = [\"{KYLE}\", \"{OTHER}\"]\n"
+    )))
+    .unwrap();
+    let why = c.problem().expect("refused");
+    assert_eq!(
+        why,
+        format!(
+            "[approvals] \"{OTHER}\" is not in [allow] users: an approver who is not heard could never answer"
+        )
+    );
+}
+
+#[test]
+fn unknown_keys_are_errors() {
+    assert!(Config::parse(&text("[approvals]\napprovers = []\n")).is_err());
+    assert!(Config::parse(&text("[approvals]\nusers = []\nttl = 5\n")).is_err());
+}