1 files changed, 64 insertions, 0 deletions
diff --git a/third_party/rust/minimal-lexical/tests/rounding_tests.rs b/third_party/rust/minimal-lexical/tests/rounding_tests.rs
new file mode 100644
index 0000000000..794d696fb8
--- /dev/null
+++ b/third_party/rust/minimal-lexical/tests/rounding_tests.rs
@@ -0,0 +1,64 @@
+use minimal_lexical::extended_float::ExtendedFloat;
+use minimal_lexical::rounding;
+
+#[test]
+fn round_test() {
+    let mut fp = ExtendedFloat {
+        mant: 9223372036854776832,
+        exp: -10,
+    };
+    rounding::round::<f64, _>(&mut fp, |f, s| {
+        f.mant >>= s;
+        f.exp += s;
+    });
+    assert_eq!(fp.mant, 0);
+    assert_eq!(fp.exp, 1);
+
+    let mut fp = ExtendedFloat {
+        mant: 9223372036854776832,
+        exp: -10,
+    };
+    rounding::round::<f64, _>(&mut fp, |f, s| {
+        f.mant >>= s;
+        f.exp += s;
+        // Round-up.
+        f.mant += 1;
+    });
+    assert_eq!(fp.mant, 1);
+    assert_eq!(fp.exp, 1);
+
+    // Round-down
+    let mut fp = ExtendedFloat {
+        mant: 9223372036854776832,
+        exp: -10,
+    };
+    rounding::round::<f64, _>(&mut fp, |f, s| {
+        rounding::round_nearest_tie_even(f, s, |is_odd, is_halfway, is_above| {
+            is_above || (is_odd && is_halfway)
+        });
+    });
+    assert_eq!(fp.mant, 0);
+    assert_eq!(fp.exp, 1);
+
+    // Round up
+    let mut fp = ExtendedFloat {
+        mant: 9223372036854778880,
+        exp: -10,
+    };
+    rounding::round::<f64, _>(&mut fp, |f, s| {
+        rounding::round_nearest_tie_even(f, s, |is_odd, is_halfway, is_above| {
+            is_above || (is_odd && is_halfway)
+        });
+    });
+    assert_eq!(fp.mant, 2);
+    assert_eq!(fp.exp, 1);
+
+    // Round down
+    let mut fp = ExtendedFloat {
+        mant: 9223372036854778880,
+        exp: -10,
+    };
+    rounding::round::<f64, _>(&mut fp, rounding::round_down);
+    assert_eq!(fp.mant, 1);
+    assert_eq!(fp.exp, 1);
+}