1 files changed, 169 insertions, 0 deletions
diff --git a/library/std/src/io/readbuf/tests.rs b/library/std/src/io/readbuf/tests.rs
new file mode 100644
index 00000000000..ef5fe798f4c
--- /dev/null
+++ b/library/std/src/io/readbuf/tests.rs
@@ -0,0 +1,169 @@
+use super::ReadBuf;
+use crate::mem::MaybeUninit;
+
+/// Test that ReadBuf has the correct numbers when created with new
+#[test]
+fn new() {
+    let mut buf = [0; 16];
+    let rbuf = ReadBuf::new(&mut buf);
+
+    assert_eq!(rbuf.filled_len(), 0);
+    assert_eq!(rbuf.initialized_len(), 16);
+    assert_eq!(rbuf.capacity(), 16);
+    assert_eq!(rbuf.remaining(), 16);
+}
+
+/// Test that ReadBuf has the correct numbers when created with uninit
+#[test]
+fn uninit() {
+    let mut buf = [MaybeUninit::uninit(); 16];
+    let rbuf = ReadBuf::uninit(&mut buf);
+
+    assert_eq!(rbuf.filled_len(), 0);
+    assert_eq!(rbuf.initialized_len(), 0);
+    assert_eq!(rbuf.capacity(), 16);
+    assert_eq!(rbuf.remaining(), 16);
+}
+
+#[test]
+fn initialize_unfilled() {
+    let mut buf = [MaybeUninit::uninit(); 16];
+    let mut rbuf = ReadBuf::uninit(&mut buf);
+
+    rbuf.initialize_unfilled();
+
+    assert_eq!(rbuf.initialized_len(), 16);
+}
+
+#[test]
+fn initialize_unfilled_to() {
+    let mut buf = [MaybeUninit::uninit(); 16];
+    let mut rbuf = ReadBuf::uninit(&mut buf);
+
+    rbuf.initialize_unfilled_to(8);
+
+    assert_eq!(rbuf.initialized_len(), 8);
+
+    rbuf.initialize_unfilled_to(4);
+
+    assert_eq!(rbuf.initialized_len(), 8);
+
+    rbuf.set_filled(8);
+
+    rbuf.initialize_unfilled_to(6);
+
+    assert_eq!(rbuf.initialized_len(), 14);
+
+    rbuf.initialize_unfilled_to(8);
+
+    assert_eq!(rbuf.initialized_len(), 16);
+}
+
+#[test]
+fn add_filled() {
+    let mut buf = [0; 16];
+    let mut rbuf = ReadBuf::new(&mut buf);
+
+    rbuf.add_filled(1);
+
+    assert_eq!(rbuf.filled_len(), 1);
+    assert_eq!(rbuf.remaining(), 15);
+}
+
+#[test]
+#[should_panic]
+fn add_filled_panic() {
+    let mut buf = [MaybeUninit::uninit(); 16];
+    let mut rbuf = ReadBuf::uninit(&mut buf);
+
+    rbuf.add_filled(1);
+}
+
+#[test]
+fn set_filled() {
+    let mut buf = [0; 16];
+    let mut rbuf = ReadBuf::new(&mut buf);
+
+    rbuf.set_filled(16);
+
+    assert_eq!(rbuf.filled_len(), 16);
+    assert_eq!(rbuf.remaining(), 0);
+
+    rbuf.set_filled(6);
+
+    assert_eq!(rbuf.filled_len(), 6);
+    assert_eq!(rbuf.remaining(), 10);
+}
+
+#[test]
+#[should_panic]
+fn set_filled_panic() {
+    let mut buf = [MaybeUninit::uninit(); 16];
+    let mut rbuf = ReadBuf::uninit(&mut buf);
+
+    rbuf.set_filled(16);
+}
+
+#[test]
+fn clear() {
+    let mut buf = [255; 16];
+    let mut rbuf = ReadBuf::new(&mut buf);
+
+    rbuf.set_filled(16);
+
+    assert_eq!(rbuf.filled_len(), 16);
+    assert_eq!(rbuf.remaining(), 0);
+
+    rbuf.clear();
+
+    assert_eq!(rbuf.filled_len(), 0);
+    assert_eq!(rbuf.remaining(), 16);
+
+    assert_eq!(rbuf.initialized(), [255; 16]);
+}
+
+#[test]
+fn assume_init() {
+    let mut buf = [MaybeUninit::uninit(); 16];
+    let mut rbuf = ReadBuf::uninit(&mut buf);
+
+    unsafe {
+        rbuf.assume_init(8);
+    }
+
+    assert_eq!(rbuf.initialized_len(), 8);
+
+    rbuf.add_filled(4);
+
+    unsafe {
+        rbuf.assume_init(2);
+    }
+
+    assert_eq!(rbuf.initialized_len(), 8);
+
+    unsafe {
+        rbuf.assume_init(8);
+    }
+
+    assert_eq!(rbuf.initialized_len(), 12);
+}
+
+#[test]
+fn append() {
+    let mut buf = [MaybeUninit::new(255); 16];
+    let mut rbuf = ReadBuf::uninit(&mut buf);
+
+    rbuf.append(&[0; 8]);
+
+    assert_eq!(rbuf.initialized_len(), 8);
+    assert_eq!(rbuf.filled_len(), 8);
+    assert_eq!(rbuf.filled(), [0; 8]);
+
+    rbuf.clear();
+
+    rbuf.append(&[1; 16]);
+
+    assert_eq!(rbuf.initialized_len(), 16);
+    assert_eq!(rbuf.filled_len(), 16);
+    assert_eq!(rbuf.filled(), [1; 16]);
+}