Stop returning body data from `POST /api/auth/login`.

As with `/api/setup`, the response was an ad-hoc choice, which we are not using and which constrains future development just by existing.

8 files changed, 38 insertions, 44 deletions

diff --git a/docs/api/authentication.md b/docs/api/authentication.md
index fbd5959..7694609 100644
--- a/docs/api/authentication.md
+++ b/docs/api/authentication.md
@@ -71,32 +71,15 @@ The request must have the following fields:
 
 <!-- This prose is duplicated by 03-initial-setup.md and in 04-invitations.md, with small changes for context. If you edit it here, edit it there, too. -->
 
-This endpoint will respond with a status of
-`200 Okay` when successful. The body of the response will be a JSON object describing the authenticated user:
-
-```json
-{
-  "id": "Uabcd1234",
-  "name": "Andrea"
-}
-```
-
-The response will include the following fields:
-
-| Field  | Type   | Description                    |
-| :----- | :----- | :----------------------------- |
-| `id`   | string | The authenticated user's ID.   |
-| `name` | string | The authenticated user's name. |
+This endpoint will respond with a status of `204 No Content` when successful.
 
-The response will include a `Set-Cookie` header for the
-`identity` cookie, providing the client with a newly-minted identity token associated with the user identified in the request. This token's value must be kept confidential.
+The response will include a `Set-Cookie` header for the `identity` cookie, providing the client with a newly-minted identity token associated with the user identified in the request. This token's value must be kept confidential.
 
 The cookie will expire if it is not used regularly.
 
 ### Authentication failure
 
-This endpoint will respond with a status of
-`401 Unauthorized` if the login name and password do not correspond to an existing user.
+This endpoint will respond with a status of `401 Unauthorized` if the login name and password do not correspond to an existing user.
 
 ## `POST /api/auth/logout`
 
@@ -114,8 +97,7 @@ The request must be an empty JSON object.
 
 This endpoint will respond with a status of `204 No Content` when successful.
 
-The response will include a `Set-Cookie` header that clears the
-`identity` cookie. Regardless of whether the client clears the cookie, the service also invalidates the token.
+The response will include a `Set-Cookie` header that clears the `identity` cookie. Regardless of whether the client clears the cookie, the service also invalidates the token.
 
 ## `POST /api/password`
 
diff --git a/src/invite/handlers/accept/test.rs b/src/invite/handlers/accept/test.rs
index cb13900..7139985 100644
--- a/src/invite/handlers/accept/test.rs
+++ b/src/invite/handlers/accept/test.rs
@@ -47,11 +47,16 @@ async fn valid_invite() {
 
     // Verify that the given credentials can log in
 
-    let (login, _) = app
+    let secret = app
         .tokens()
         .login(&name, &password, &fixtures::now())
         .await
         .expect("credentials given on signup are valid");
+    let (_, login) = app
+        .tokens()
+        .validate(&secret, &fixtures::now())
+        .await
+        .expect("validating a newly-issued token secret succeeds");
     assert_eq!(response, login);
 }
 
diff --git a/src/setup/handlers/setup/test.rs b/src/setup/handlers/setup/test.rs
index 69e44c2..4a37690 100644
--- a/src/setup/handlers/setup/test.rs
+++ b/src/setup/handlers/setup/test.rs
@@ -34,11 +34,16 @@ async fn fresh_instance() {
 
     // Verify that the given credentials can log in
 
-    let (login, _) = app
+    let secret = app
         .tokens()
         .login(&name, &password, &fixtures::now())
         .await
         .expect("credentials given on signup are valid");
+    let (_, login) = app
+        .tokens()
+        .validate(&secret, &fixtures::now())
+        .await
+        .expect("validating a newly-issued token secret succeeds");
     assert_eq!(name, login.name);
 }
 
diff --git a/src/test/fixtures/cookie.rs b/src/test/fixtures/cookie.rs
index 41779db..f5a32a6 100644
--- a/src/test/fixtures/cookie.rs
+++ b/src/test/fixtures/cookie.rs
@@ -18,13 +18,13 @@ pub async fn logged_in(
     now: &RequestedAt,
 ) -> IdentityCookie {
     let (name, password) = credentials;
-    let (_, token) = app
+    let secret = app
         .tokens()
         .login(name, password, now)
         .await
         .expect("should succeed given known-valid credentials");
 
-    IdentityCookie::new().set(token)
+    IdentityCookie::new().set(secret)
 }
 
 pub fn secret(identity: &IdentityCookie) -> Secret {
diff --git a/src/token/app.rs b/src/token/app.rs
index 49f9a45..7d70534 100644
--- a/src/token/app.rs
+++ b/src/token/app.rs
@@ -32,7 +32,7 @@ impl<'a> Tokens<'a> {
         name: &Name,
         password: &Password,
         login_at: &DateTime,
-    ) -> Result<(User, Secret), LoginError> {
+    ) -> Result<Secret, LoginError> {
         let mut tx = self.db.begin().await?;
         let (user, stored_hash) = tx
             .auth()
@@ -47,18 +47,16 @@ impl<'a> Tokens<'a> {
         // if the account is deleted during that time.
         tx.commit().await?;
 
-        let snapshot = user.as_snapshot().ok_or(LoginError::Rejected)?;
+        user.as_snapshot().ok_or(LoginError::Rejected)?;
 
-        let token = if stored_hash.verify(password)? {
+        if stored_hash.verify(password)? {
             let mut tx = self.db.begin().await?;
-            let token = tx.tokens().issue(&user, login_at).await?;
+            let secret = tx.tokens().issue(&user, login_at).await?;
             tx.commit().await?;
-            token
+            Ok(secret)
         } else {
-            Err(LoginError::Rejected)?
-        };
-
-        Ok((snapshot, token))
+            Err(LoginError::Rejected)
+        }
     }
 
     pub async fn change_password(
diff --git a/src/user/handlers/login/mod.rs b/src/user/handlers/login/mod.rs
index da88885..d3e0e8c 100644
--- a/src/user/handlers/login/mod.rs
+++ b/src/user/handlers/login/mod.rs
@@ -7,11 +7,11 @@ use axum::{
 use crate::{
     app::App,
     clock::RequestedAt,
+    empty::Empty,
     error::Internal,
     name::Name,
     password::Password,
     token::{app, extract::IdentityCookie},
-    user::User,
 };
 
 #[cfg(test)]
@@ -22,14 +22,14 @@ pub async fn handler(
     RequestedAt(now): RequestedAt,
     identity: IdentityCookie,
     Json(request): Json<Request>,
-) -> Result<(IdentityCookie, Json<User>), Error> {
-    let (user, secret) = app
+) -> Result<(IdentityCookie, Empty), Error> {
+    let secret = app
         .tokens()
         .login(&request.name, &request.password, &now)
         .await
         .map_err(Error)?;
     let identity = identity.set(secret);
-    Ok((identity, Json(user)))
+    Ok((identity, Empty))
 }
 
 #[derive(serde::Deserialize)]
diff --git a/src/user/handlers/login/test.rs b/src/user/handlers/login/test.rs
index b8f24f6..bdd1957 100644
--- a/src/user/handlers/login/test.rs
+++ b/src/user/handlers/login/test.rs
@@ -1,6 +1,6 @@
 use axum::extract::{Json, State};
 
-use crate::{test::fixtures, token::app};
+use crate::{empty::Empty, test::fixtures, token::app};
 
 #[tokio::test]
 async fn correct_credentials() {
@@ -17,14 +17,13 @@ async fn correct_credentials() {
         name: name.clone(),
         password,
     };
-    let (identity, Json(response)) =
+    let (identity, Empty) =
         super::handler(State(app.clone()), logged_in_at, identity, Json(request))
             .await
             .expect("logged in with valid credentials");
 
     // Verify the return value's basic structure
 
-    assert_eq!(name, response.name);
     let secret = identity
         .secret()
         .expect("logged in with valid credentials issues an identity cookie");
@@ -38,7 +37,7 @@ async fn correct_credentials() {
         .await
         .expect("identity secret is valid");
 
-    assert_eq!(response, validated_login);
+    assert_eq!(name, validated_login.name);
 }
 
 #[tokio::test]
diff --git a/src/user/handlers/password/test.rs b/src/user/handlers/password/test.rs
index 42e41d8..278d27b 100644
--- a/src/user/handlers/password/test.rs
+++ b/src/user/handlers/password/test.rs
@@ -58,10 +58,15 @@ async fn password_change() {
     assert!(matches!(login_err, LoginError::Rejected));
 
     // Verify that our new password is valid
-    let (login, _) = app
+    let secret = app
         .tokens()
         .login(&name, &to, &fixtures::now())
         .await
         .expect("logging in with the new password should succeed");
+    let (_, login) = app
+        .tokens()
+        .validate(&secret, &fixtures::now())
+        .await
+        .expect("validating a newly-issued token secret succeeds");
     assert_eq!(identity.user, login);
 }