1 files changed, 54 insertions, 0 deletions
diff --git a/third_party/rust/getrandom/tests/custom.rs b/third_party/rust/getrandom/tests/custom.rs
new file mode 100644
index 0000000000..b085094be8
--- /dev/null
+++ b/third_party/rust/getrandom/tests/custom.rs
@@ -0,0 +1,54 @@
+// Test that a custom handler works on wasm32-unknown-unknown
+#![cfg(all(
+    target_arch = "wasm32",
+    target_os = "unknown",
+    feature = "custom",
+    not(feature = "js")
+))]
+
+use wasm_bindgen_test::wasm_bindgen_test as test;
+
+use core::num::NonZeroU32;
+use getrandom::{getrandom, register_custom_getrandom, Error};
+
+fn len7_err() -> Error {
+    NonZeroU32::new(Error::INTERNAL_START + 7).unwrap().into()
+}
+
+fn super_insecure_rng(buf: &mut [u8]) -> Result<(), Error> {
+    // `getrandom` guarantees it will not call any implementation if the output
+    // buffer is empty.
+    assert!(!buf.is_empty());
+    // Length 7 buffers return a custom error
+    if buf.len() == 7 {
+        return Err(len7_err());
+    }
+    // Otherwise, fill bytes based on input length
+    let mut start = buf.len() as u8;
+    for b in buf {
+        *b = start;
+        start = start.wrapping_mul(3);
+    }
+    Ok(())
+}
+
+register_custom_getrandom!(super_insecure_rng);
+
+use getrandom::getrandom as getrandom_impl;
+mod common;
+
+#[test]
+fn custom_rng_output() {
+    let mut buf = [0u8; 4];
+    assert_eq!(getrandom(&mut buf), Ok(()));
+    assert_eq!(buf, [4, 12, 36, 108]);
+
+    let mut buf = [0u8; 3];
+    assert_eq!(getrandom(&mut buf), Ok(()));
+    assert_eq!(buf, [3, 9, 27]);
+}
+
+#[test]
+fn rng_err_output() {
+    assert_eq!(getrandom(&mut [0; 7]), Err(len7_err()));
+}