1 files changed, 55 insertions, 0 deletions
diff --git a/third_party/rust/failure_derive/tests/tests.rs b/third_party/rust/failure_derive/tests/tests.rs
new file mode 100644
index 0000000000..4e73255ef3
--- /dev/null
+++ b/third_party/rust/failure_derive/tests/tests.rs
@@ -0,0 +1,55 @@
+extern crate failure;
+#[macro_use]
+extern crate failure_derive;
+
+#[derive(Fail, Debug)]
+#[fail(display = "An error has occurred.")]
+struct UnitError;
+
+#[test]
+fn unit_struct() {
+    let s = format!("{}", UnitError);
+    assert_eq!(&s[..], "An error has occurred.");
+}
+
+#[derive(Fail, Debug)]
+#[fail(display = "Error code: {}", code)]
+struct RecordError {
+    code: u32,
+}
+
+#[test]
+fn record_struct() {
+    let s = format!("{}", RecordError { code: 0 });
+    assert_eq!(&s[..], "Error code: 0");
+}
+
+#[derive(Fail, Debug)]
+#[fail(display = "Error code: {}", _0)]
+struct TupleError(i32);
+
+#[test]
+fn tuple_struct() {
+    let s = format!("{}", TupleError(2));
+    assert_eq!(&s[..], "Error code: 2");
+}
+
+#[derive(Fail, Debug)]
+enum EnumError {
+    #[fail(display = "Error code: {}", code)]
+    StructVariant { code: i32 },
+    #[fail(display = "Error: {}", _0)]
+    TupleVariant(&'static str),
+    #[fail(display = "An error has occurred.")]
+    UnitVariant,
+}
+
+#[test]
+fn enum_error() {
+    let s = format!("{}", EnumError::StructVariant { code: 2 });
+    assert_eq!(&s[..], "Error code: 2");
+    let s = format!("{}", EnumError::TupleVariant("foobar"));
+    assert_eq!(&s[..], "Error: foobar");
+    let s = format!("{}", EnumError::UnitVariant);
+    assert_eq!(&s[..], "An error has occurred.");
+}