feat: make it work

.github/workflows/release.yaml

@@ -0,0 +1,35 @@
+name: Create release
+
+on:
+  push:
+    tags:
+      - "v*"
+
+jobs:
+  create-release:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Create Release
+        uses: taiki-e/create-gh-release-action@v1
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+
+  upload-artifacts:
+    strategy:
+      matrix:
+        os:
+          - ubuntu-latest
+          - macos-latest
+          - windows-latest
+
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Upload binaries
+        uses: taiki-e/upload-rust-binary-action@v1
+        with:
+          bin: what-rust-changed
+          token: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/rust.yml

@@ -0,0 +1,36 @@
+name: Build
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+env:
+  COLUMNS: 250
+  CARGO_INCREMENTAL: 0
+  RUSTFLAGS: "-W rust-2021-compatibility -D warnings"
+  RUST_BACKTRACE: short
+  NEXTEST_PROFILE: ci
+  CI: 1
+
+jobs:
+  build-rust:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: dtolnay/[email protected]
+        with:
+          components: rustfmt
+
+      - uses: Swatinem/rust-cache@v2
+
+      - name: Check formatting
+        shell: bash
+        run: cargo fmt --check
+
+      - name: Build
+        shell: bash
+        run: cargo build

Cargo.toml

@@ -8,4 +8,5 @@ determinator = "0.12"
 guppy = "0.17"
 itertools = "0.13"
 serde = "1"
-serde_json = "1"
+serde_json = "1"
+toml = "0.8"

src/config.rs

@@ -0,0 +1,29 @@
+use std::fs::read_to_string;
+
+pub fn load() -> Config {
+    do_load().unwrap_or_default()
+}
+
+fn do_load() -> Option<Config> {
+    let path = std::env::var("WHAT_RUST_CHANGED_CONFIG").ok()?;
+
+    eprintln!("Loading config from {path}");
+
+    let data = read_to_string(path).expect("to be able to read named config file");
+
+    toml::from_str(&data).expect("invalid config format")
+}
+
+#[derive(serde::Serialize, serde::Deserialize, Default)]
+#[serde(rename_all = "kebab-case")]
+pub struct Config {
+    /// Packages that shouldn't automatically be included in test runs
+    pub ignore_test_packages: Vec<String>,
+
+    /// Packages that require docker for their tests and should be put
+    /// into a separate section of the output
+    pub docker_test_packages: Vec<String>,
+
+    #[serde(flatten)]
+    pub determinator_rules: determinator::rules::DeterminatorRules,
+}

src/guppy_ext.rs

@@ -0,0 +1,62 @@
+use guppy::graph::{BuildTarget, BuildTargetKind};
+
+pub trait PackageMetadataExt {
+    fn has_test_targets(&self) -> bool;
+    fn binary_targets(&self) -> Vec<BuildTarget<'_>>;
+}
+
+impl PackageMetadataExt for guppy::graph::PackageMetadata<'_> {
+    fn has_test_targets(&self) -> bool {
+        let package_root_path = self
+            .manifest_path()
+            .parent()
+            .expect("all packages to have manifests with one parent");
+
+        self.build_targets()
+            .filter(|target| {
+                matches!(
+                    target.kind(),
+                    BuildTargetKind::Binary | BuildTargetKind::LibraryOrExample(_)
+                )
+            })
+            .any(|target| {
+                let relative_path = target
+                    .path()
+                    .strip_prefix(package_root_path)
+                    .expect("targets to live inside package");
+
+                let Some(root_folder) = relative_path.components().next() else {
+                    return false;
+                };
+
+                let root_folder = root_folder.as_str();
+
+                // Unfortunately doesn't seem to be any way to tell whether something rooted in
+                // src actually has tests or not, so best to just assume they do
+                root_folder == "tests" || root_folder == "src"
+            })
+    }
+
+    fn binary_targets(&self) -> Vec<BuildTarget<'_>> {
+        let package_root_path = self
+            .manifest_path()
+            .parent()
+            .expect("all packages to have manifests with one parent");
+
+        self.build_targets()
+            .filter(|target| matches!(target.kind(), BuildTargetKind::Binary))
+            .filter(|target| {
+                let relative_path = target
+                    .path()
+                    .strip_prefix(package_root_path)
+                    .expect("targets to live inside package");
+
+                let Some(root_folder) = relative_path.components().next() else {
+                    return false;
+                };
+
+                root_folder.as_str() == "src" && relative_path.file_name() == Some("main.rs")
+            })
+            .collect()
+    }
+}