Make the web app work offline and update itself (#239)

xtask/src/main.rs

@@ -1,6 +1,6 @@
 //! Workspace tooling: `cargo xtask <command>`.
 //!
-//! Pure Rust (std + serde_json). External tools (`cargo`) are invoked through
+//! Pure Rust (std, serde_json and sha2). External tools (`cargo`) are invoked through
 //! `std::process::Command`.
 
 mod assets;
@@ -10,6 +10,8 @@ mod i18n;
 mod layers;
 mod licences;
 mod test;
+mod web_offline;
+mod web_offline_test;
 
 use std::path::{Path, PathBuf};
 use std::process::{Command, ExitCode};
@@ -45,8 +47,15 @@ commands:
                   build the tests with the ci profile, then run every test binary at once
                   (and the doc tests alongside)
   wasm            cargo check every library crate and the web app for wasm32-unknown-unknown
+  web-offline [DIR]
+                  write the web build's service worker (sw.js: offline use, updates); run by
+                  Trunk after release builds of apps/solidcraft-web, or on a built site in DIR
+  web-offline-test [--site DIR]
+                  check in headless Chrome that the web app works offline and updates to a new
+                  build (a stand-in app, or the web build in DIR such as dist/web)
   ci              fmt --check, assets, licences --check, layers, clippy -D warnings, then the tests
-                  with the wasm check alongside (stops at the first failing step)
+                  with the wasm check alongside, then web-offline-test when Chrome is installed
+                  (stops at the first failing step)
 ";
 
 fn main() -> ExitCode {
@@ -69,6 +78,11 @@ fn main() -> ExitCode {
         }
         Some("ci") => cmd_ci(),
         Some("wasm") => cmd_wasm(),
+        Some("web-offline") => web_offline::run(&root(), rest.first().copied()),
+        Some("web-offline-test") => {
+            let site = rest.iter().position(|a| *a == "--site").and_then(|i| rest.get(i + 1)).copied();
+            web_offline_test::run(&root(), site, true)
+        }
         Some("-h" | "--help" | "help") | None => {
             print!("{USAGE}");
             Ok(())
@@ -340,6 +354,7 @@ fn cmd_ci() -> Result<(), String> {
     run(c, "cargo clippy -D warnings")?;
     let (wasm, n) = wasm_check()?;
     test::run(&[], &[], vec![(format!("wasm32-unknown-unknown check ({n} crates)"), wasm), test::doc_tests(&[], &[])])?;
+    web_offline_test::run(&root(), None, false)?;
     eprintln!("ci: all gates passed");
     Ok(())
 }