Implement test for optional non-dev dependency fix

Author: smoelius

.gitignore

@@ -1 +1 @@
-/target
+target

fixtures/optional_non_dev_dep/Cargo.lock

@@ -0,0 +1,13 @@
+[package]
+name = "optional_non_dev_dep"
+version = "0.1.0"
+edition = "2024"
+publish = false
+
+[dependencies]
+libz-rs-sys = { version = "=0.5.5", optional = true }
+
+[dev-dependencies]
+libz-rs-sys = "=0.5.5"
+
+[workspace]

fixtures/optional_non_dev_dep/Cargo.toml

@@ -0,0 +1,14 @@
+pub fn add(left: u64, right: u64) -> u64 {
+    left + right
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn it_works() {
+        let result = add(2, 2);
+        assert_eq!(result, 4);
+    }
+}

fixtures/optional_non_dev_dep/src/lib.rs

@@ -231,7 +231,7 @@ pub fn comma_separated_list(list: &[String]) -> String {
 #[cfg(test)]
 mod tests {
     use super::{sourced_dependencies_from_metadata, SourcedPackage};
-    use cargo_metadata::Metadata;
+    use cargo_metadata::{Metadata, MetadataCommand};
     use std::{
         cmp::Ordering,
         env::var,
@@ -281,7 +281,8 @@ mod tests {
         }
     }
 
-    // `cargo` has `snapbox` as a dev dependency. `snapbox` has `snapbox-macros` as a normal dependency.
+    // `cargo` has `snapbox` as a dev dependency. `snapbox` has `snapbox-macros` as a normal
+    // dependency.
 
     #[test]
     fn cargo() {
@@ -306,6 +307,22 @@ mod tests {
         assert!(deps.iter().any(|dep| dep.package.name == "snapbox-macros"));
     }
 
+    #[test]
+    fn optional_dependency_excluded_when_not_activated() {
+        let metadata = MetadataCommand::new()
+            .current_dir("fixtures/optional_non_dev_dep")
+            .exec()
+            .unwrap();
+
+        let deps = sourced_dependencies_from_metadata(metadata.clone(), false).unwrap();
+        assert!(deps.iter().any(|dep| dep.package.name == "libz-rs-sys"));
+
+        let deps_no_dev = sourced_dependencies_from_metadata(metadata, true).unwrap();
+        assert!(!deps_no_dev
+            .iter()
+            .any(|dep| dep.package.name == "libz-rs-sys"));
+    }
+
     fn sourced_dependencies_from_file(path: impl AsRef<Path>) -> Vec<SourcedPackage> {
         let contents = read_to_string(path).unwrap();
         serde_json::from_str::<Vec<SourcedPackage>>(&contents).unwrap()