test(util): port TarTest

All cases reuse the existing PHP fixtures under
composer/tests/Composer/Test/Util/Fixtures/Tar. Marked #[ignore] because
PharData::new is todo!() in the php-shim.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

2 files changed, 59 insertions, 0 deletions

diff --git a/crates/shirabe/tests/util/main.rs b/crates/shirabe/tests/util/main.rs
index 349aeb6..2a5e81a 100644
--- a/crates/shirabe/tests/util/main.rs
+++ b/crates/shirabe/tests/util/main.rs
@@ -1,3 +1,4 @@
 mod forgejo_url_test;
 mod platform_test;
 mod silencer_test;
+mod tar_test;
diff --git a/crates/shirabe/tests/util/tar_test.rs b/crates/shirabe/tests/util/tar_test.rs
index 6bba0b5..3a8aa75 100644
--- a/crates/shirabe/tests/util/tar_test.rs
+++ b/crates/shirabe/tests/util/tar_test.rs
@@ -1 +1,59 @@
 //! ref: composer/tests/Composer/Test/Util/TarTest.php
+
+use shirabe::util::tar::Tar;
+
+/// Reuses the PHP fixtures under composer/tests/Composer/Test/Util/Fixtures/Tar.
+fn fixture(name: &str) -> String {
+    format!(
+        "{}/../../composer/tests/Composer/Test/Util/Fixtures/Tar/{}",
+        env!("CARGO_MANIFEST_DIR"),
+        name
+    )
+}
+
+#[test]
+#[ignore = "PharData::new is todo!() in the php-shim"]
+fn test_returns_nullif_the_tar_is_not_found() {
+    let result = Tar::get_composer_json(&fixture("invalid.zip")).unwrap();
+
+    assert_eq!(None, result);
+}
+
+#[test]
+#[ignore = "PharData::new is todo!() in the php-shim"]
+fn test_returns_null_if_the_tar_is_empty() {
+    let result = Tar::get_composer_json(&fixture("empty.tar.gz")).unwrap();
+    assert_eq!(None, result);
+}
+
+#[test]
+#[ignore = "PharData::new is todo!() in the php-shim"]
+fn test_throws_exception_if_the_tar_has_no_composer_json() {
+    assert!(Tar::get_composer_json(&fixture("nojson.tar.gz")).is_err());
+}
+
+#[test]
+#[ignore = "PharData::new is todo!() in the php-shim"]
+fn test_throws_exception_if_the_composer_json_is_in_a_sub_subfolder() {
+    assert!(Tar::get_composer_json(&fixture("subfolders.tar.gz")).is_err());
+}
+
+#[test]
+#[ignore = "PharData::new is todo!() in the php-shim"]
+fn test_returns_composer_json_in_tar_root() {
+    let result = Tar::get_composer_json(&fixture("root.tar.gz")).unwrap();
+    assert_eq!(Some("{\n    \"name\": \"foo/bar\"\n}\n".to_string()), result);
+}
+
+#[test]
+#[ignore = "PharData::new is todo!() in the php-shim"]
+fn test_returns_composer_json_in_first_folder() {
+    let result = Tar::get_composer_json(&fixture("folder.tar.gz")).unwrap();
+    assert_eq!(Some("{\n    \"name\": \"foo/bar\"\n}\n".to_string()), result);
+}
+
+#[test]
+#[ignore = "PharData::new is todo!() in the php-shim"]
+fn test_multiple_top_level_dirs_is_invalid() {
+    assert!(Tar::get_composer_json(&fixture("multiple.tar.gz")).is_err());
+}