Add tests for ignoring symlinks

tests/testsuite/package.rs

@@ -806,6 +806,84 @@ Caused by:
         .run();
 }
 
+#[cargo_test]
+#[cfg(not(windows))] // https://github.com/libgit2/libgit2/issues/6250
+/// Test that /dir and /dir/ matches symlinks to directories.
+fn gitignore_symlink_dir() {
+    if !symlink_supported() {
+        return;
+    }
+
+    let (p, _repo) = git::new_repo("foo", |p| {
+        p.file("src/main.rs", r#"fn main() { println!("hello"); }"#)
+            .symlink_dir("src", "src1")
+            .symlink_dir("src", "src2")
+            .symlink_dir("src", "src3")
+            .symlink_dir("src", "src4")
+            .file(".gitignore", "/src1\n/src2/\nsrc3\nsrc4/")
+    });
+
+    p.cargo("package -l --no-metadata")
+        .with_stderr("")
+        .with_stdout(
+            "\
+.cargo_vcs_info.json
+.gitignore
+Cargo.lock
+Cargo.toml
+Cargo.toml.orig
+src/main.rs
+",
+        )
+        .run();
+}
+
+#[cargo_test]
+#[cfg(not(windows))] // https://github.com/libgit2/libgit2/issues/6250
+/// Test that /dir and /dir/ matches symlinks to directories in dirty working directory.
+fn gitignore_symlink_dir_dirty() {
+    if !symlink_supported() {
+        return;
+    }
+
+    let (p, _repo) = git::new_repo("foo", |p| {
+        p.file("src/main.rs", r#"fn main() { println!("hello"); }"#)
+            .file(".gitignore", "/src1\n/src2/\nsrc3\nsrc4/")
+    });
+
+    p.symlink("src", "src1");
+    p.symlink("src", "src2");
+    p.symlink("src", "src3");
+    p.symlink("src", "src4");
+
+    p.cargo("package -l --no-metadata")
+        .with_stderr("")
+        .with_stdout(
+            "\
+.cargo_vcs_info.json
+.gitignore
+Cargo.lock
+Cargo.toml
+Cargo.toml.orig
+src/main.rs
+",
+        )
+        .run();
+
+    p.cargo("package -l --no-metadata --allow-dirty")
+        .with_stderr("")
+        .with_stdout(
+            "\
+.gitignore
+Cargo.lock
+Cargo.toml
+Cargo.toml.orig
+src/main.rs
+",
+        )
+        .run();
+}
+
 #[cargo_test]
 /// Tests if a symlink to a directory is properly included.
 ///