Do the Trunk build check as an end-to-end test

This consolidates our whole CI workflow into `cargo test`.

.forgejo/workflows/continuous-integration.yaml

@@ -3,22 +3,11 @@ on:
   push:
     branches: [main]
 jobs:
-  # build the application, reporting success if there are no errors or warnings
-  build:
-    runs-on: docker
-    container:
-      image: cimg/rust:1.85-node
-    defaults:
-      run:
-        working-directory: app-proto
-    steps:
-      - uses: https://code.forgejo.org/actions/checkout@v4
-      - uses: ./.forgejo/setup-trunk
-      - run: RUSTFLAGS='-D warnings' trunk build
-  
   # run the automated tests, reporting success if the tests pass and were built
   # without warnings. the examples are run as tests, because we've configured
-  # each example target with `test = true` and `harness = false` in Cargo.toml
+  # each example target with `test = true` and `harness = false` in Cargo.toml.
+  # Trunk build failures caused by problems outside the Rust source code, like
+  # missing assets, should be caught by `trunk_build_test`
   test:
     runs-on: docker
     container:
@@ -28,4 +17,5 @@ jobs:
         working-directory: app-proto
     steps:
       - uses: https://code.forgejo.org/actions/checkout@v4
+      - uses: ./.forgejo/setup-trunk
       - run: RUSTFLAGS='-D warnings' cargo test

app-proto/src/main.rs

@@ -5,6 +5,9 @@ mod engine;
 mod outline;
 mod specified;
 
+#[cfg(test)]
+mod tests;
+
 use rustc_hash::FxHashSet;
 use sycamore::prelude::*;
 

app-proto/src/tests.rs

@@ -0,0 +1,14 @@
+use std::process::Command;
+
+// build and bundle the application, reporting success if there are no errors or
+// warnings. to see this test fail while others succeed, try moving `index.html`
+// or one of the assets that it links to
+#[test]
+fn trunk_build_test() {
+    let build_status = Command::new("trunk")
+        .arg("build")
+        .env("RUSTFLAGS", "-D warnings")
+        .status()
+        .expect("Call to Trunk failed");
+    assert!(build_status.success());
+}