test: add tests for optional dependency resolution check

Author: Saplyn

tests/testsuite/main.rs

@@ -164,6 +164,7 @@ mod registry_overlay;
 mod rename_deps;
 mod replace;
 mod required_features;
+mod resolve_optional_dependency;
 mod run;
 mod rust_version;
 mod rustc;

tests/testsuite/resolve_optional_dependency.rs

@@ -0,0 +1,35 @@
+use crate::prelude::*;
+use cargo_test_support::project;
+
+#[cfg(target_os = "linux", target_arch = "x86_64")]
+#[cargo_test]
+fn cargo_test_should_not_demand_not_required_dep() {
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+[package]
+name = "sample"
+version = "0.1.0"
+edition = "2024"
+
+[features]
+default = ["feat"]
+feat = ["dep:ipconfig"]
+
+[target.'cfg(windows)'.dependencies]
+ipconfig = { version = "0.3.2", optional = true }
+
+[[example]]
+name = "demo"
+required-features = ["feat"]
+"#,
+        )
+        .file("src/main.rs", "fn main() {}")
+        .file("examples/demo.rs", "fn main() {}")
+        .build();
+
+    p.cargo("fetch --target=x86_64-unknown-linux-gnu").run();
+    p.cargo("test --target=x86_64-unknown-linux-gnu --frozen")
+        .run();
+}