Remove unused response bodies from a number of API endpoints.

This removes the response body from the following methods:

* `POST /api/setup`
* `POST /api/auth/login`
* `POST /api/invite/:id`
* `POST /api/password`

The bodies returned from these methods were something of a rough guess as to what might be useful. Actual client development has shown that we don't use _any_ of the data from any of these API responses, so let's not tie ourselves to future compatibility by continuing to send them. We can add a body to a bodyless method a _lot_ more easily than we can change the body of a method that already returns one, after all.

These changes are not backwards compatible for clients which care about the existing bodies. To my knowledge, there are no such clients; the included client definitely doesn't care.

## Internals

Not only does this change stop returning bodies at the API surface, but it also stops retrieving and returning values used internally to construct those responses, simplifying the code a bit in the process.

One side effect of this is that tests that need to log in a user now need to manually verify the returned token secret, to convert it back into a user, whereas the previous versions returned both a token secret and a user during password login. I don't love the increase in the size of the tests, but I think it's the right tradeoff (and this change is code net-negative anyways).

Merges no-content into main.

6 files changed, 35 insertions, 27 deletions

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/logout/mod.rs b/src/user/handlers/logout/mod.rs
index 45a376a..4450e4c 100644
--- a/src/user/handlers/logout/mod.rs
+++ b/src/user/handlers/logout/mod.rs
@@ -1,12 +1,12 @@
 use axum::{
     extract::{Json, State},
-    http::StatusCode,
     response::{IntoResponse, Response},
 };
 
 use crate::{
     app::App,
     clock::RequestedAt,
+    empty::Empty,
     error::{Internal, Unauthorized},
     token::{app, extract::IdentityCookie},
 };
@@ -19,14 +19,14 @@ pub async fn handler(
     RequestedAt(now): RequestedAt,
     identity: IdentityCookie,
     Json(_): Json<Request>,
-) -> Result<(IdentityCookie, StatusCode), Error> {
+) -> Result<(IdentityCookie, Empty), Error> {
     if let Some(secret) = identity.secret() {
         let (token, _) = app.tokens().validate(&secret, &now).await?;
         app.tokens().logout(&token).await?;
     }
 
     let identity = identity.clear();
-    Ok((identity, StatusCode::NO_CONTENT))
+    Ok((identity, Empty))
 }
 
 // This forces the only valid request to be `{}`, and not the infinite
diff --git a/src/user/handlers/logout/test.rs b/src/user/handlers/logout/test.rs
index 8dc4636..7151ddf 100644
--- a/src/user/handlers/logout/test.rs
+++ b/src/user/handlers/logout/test.rs
@@ -1,9 +1,6 @@
-use axum::{
-    extract::{Json, State},
-    http::StatusCode,
-};
+use axum::extract::{Json, State};
 
-use crate::{test::fixtures, token::app};
+use crate::{empty::Empty, test::fixtures, token::app};
 
 #[tokio::test]
 async fn successful() {
@@ -17,7 +14,7 @@ async fn successful() {
 
     // Call the endpoint
 
-    let (response_identity, response_status) = super::handler(
+    let (response_identity, Empty) = super::handler(
         State(app.clone()),
         fixtures::now(),
         identity.clone(),
@@ -29,7 +26,6 @@ async fn successful() {
     // Verify the return value's basic structure
 
     assert!(response_identity.secret().is_none());
-    assert_eq!(StatusCode::NO_CONTENT, response_status);
 
     // Verify the semantics
     let error = app
@@ -49,14 +45,13 @@ async fn no_identity() {
     // Call the endpoint
 
     let identity = fixtures::cookie::not_logged_in();
-    let (identity, status) = super::handler(State(app), fixtures::now(), identity, Json::default())
+    let (identity, Empty) = super::handler(State(app), fixtures::now(), identity, Json::default())
         .await
         .expect("logged out with no token succeeds");
 
     // Verify the return value's basic structure
 
     assert!(identity.secret().is_none());
-    assert_eq!(StatusCode::NO_CONTENT, status);
 }
 
 #[tokio::test]
diff --git a/src/user/handlers/password/mod.rs b/src/user/handlers/password/mod.rs
index c327e87..5e69c1c 100644
--- a/src/user/handlers/password/mod.rs
+++ b/src/user/handlers/password/mod.rs
@@ -7,13 +7,13 @@ use axum::{
 use crate::{
     app::App,
     clock::RequestedAt,
+    empty::Empty,
     error::Internal,
     password::Password,
     token::{
         app,
         extract::{Identity, IdentityCookie},
     },
-    user::User,
 };
 
 #[cfg(test)]
@@ -25,14 +25,14 @@ pub async fn handler(
     identity: Identity,
     cookie: IdentityCookie,
     Json(request): Json<Request>,
-) -> Result<(IdentityCookie, Json<User>), Error> {
-    let (login, secret) = app
+) -> Result<(IdentityCookie, Empty), Error> {
+    let secret = app
         .tokens()
         .change_password(&identity.user, &request.password, &request.to, &now)
         .await
         .map_err(Error)?;
     let cookie = cookie.set(secret);
-    Ok((cookie, Json(login)))
+    Ok((cookie, Empty))
 }
 
 #[derive(serde::Deserialize)]
diff --git a/src/user/handlers/password/test.rs b/src/user/handlers/password/test.rs
index 42e41d8..ffa12f3 100644
--- a/src/user/handlers/password/test.rs
+++ b/src/user/handlers/password/test.rs
@@ -1,6 +1,7 @@
 use axum::extract::{Json, State};
 
 use crate::{
+    empty::Empty,
     test::fixtures,
     token::app::{LoginError, ValidateError},
 };
@@ -20,7 +21,7 @@ async fn password_change() {
         password: password.clone(),
         to: to.clone(),
     };
-    let (new_cookie, Json(response)) = super::handler(
+    let (new_cookie, Empty) = super::handler(
         State(app.clone()),
         fixtures::now(),
         identity.clone(),
@@ -34,7 +35,15 @@ async fn password_change() {
     assert_ne!(cookie.secret(), new_cookie.secret());
 
     // Verify that we're still ourselves
-    assert_eq!(identity.user, response);
+    let new_secret = new_cookie
+        .secret()
+        .expect("we should have a secret after changing our password");
+    let (_, login) = app
+        .tokens()
+        .validate(&new_secret, &fixtures::now())
+        .await
+        .expect("the newly-issued secret should be valid");
+    assert_eq!(identity.user, login);
 
     // Verify that our original token is no longer valid
     let validate_err = app
@@ -58,10 +67,15 @@ 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);
 }