Add tests for rounding of ties during float formatting

1 files changed, 120 insertions, 0 deletions

diff --git a/library/core/tests/fmt/float.rs b/library/core/tests/fmt/float.rs
index bc0bef6d776..003782f34dc 100644
--- a/library/core/tests/fmt/float.rs
+++ b/library/core/tests/fmt/float.rs
@@ -25,6 +25,66 @@ fn test_format_f64() {
 }
 
 #[test]
+fn test_format_f64_rounds_ties_to_even() {
+    assert_eq!("0", format!("{:.0}", 0.5f64));
+    assert_eq!("2", format!("{:.0}", 1.5f64));
+    assert_eq!("2", format!("{:.0}", 2.5f64));
+    assert_eq!("4", format!("{:.0}", 3.5f64));
+    assert_eq!("4", format!("{:.0}", 4.5f64));
+    assert_eq!("6", format!("{:.0}", 5.5f64));
+    assert_eq!("128", format!("{:.0}", 127.5f64));
+    assert_eq!("128", format!("{:.0}", 128.5f64));
+    assert_eq!("0.2", format!("{:.1}", 0.25f64));
+    assert_eq!("0.8", format!("{:.1}", 0.75f64));
+    assert_eq!("0.12", format!("{:.2}", 0.125f64));
+    assert_eq!("0.88", format!("{:.2}", 0.875f64));
+    assert_eq!("0.062", format!("{:.3}", 0.062f64));
+    assert_eq!("-0", format!("{:.0}", -0.5f64));
+    assert_eq!("-2", format!("{:.0}", -1.5f64));
+    assert_eq!("-2", format!("{:.0}", -2.5f64));
+    assert_eq!("-4", format!("{:.0}", -3.5f64));
+    assert_eq!("-4", format!("{:.0}", -4.5f64));
+    assert_eq!("-6", format!("{:.0}", -5.5f64));
+    assert_eq!("-128", format!("{:.0}", -127.5f64));
+    assert_eq!("-128", format!("{:.0}", -128.5f64));
+    assert_eq!("-0.2", format!("{:.1}", -0.25f64));
+    assert_eq!("-0.8", format!("{:.1}", -0.75f64));
+    assert_eq!("-0.12", format!("{:.2}", -0.125f64));
+    assert_eq!("-0.88", format!("{:.2}", -0.875f64));
+    assert_eq!("-0.062", format!("{:.3}", -0.062f64));
+
+    assert_eq!("2e0", format!("{:.0e}", 1.5f64));
+    assert_eq!("2e0", format!("{:.0e}", 2.5f64));
+    assert_eq!("4e0", format!("{:.0e}", 3.5f64));
+    assert_eq!("4e0", format!("{:.0e}", 4.5f64));
+    assert_eq!("6e0", format!("{:.0e}", 5.5f64));
+    assert_eq!("1.28e2", format!("{:.2e}", 127.5f64));
+    assert_eq!("1.28e2", format!("{:.2e}", 128.5f64));
+    assert_eq!("-2e0", format!("{:.0e}", -1.5f64));
+    assert_eq!("-2e0", format!("{:.0e}", -2.5f64));
+    assert_eq!("-4e0", format!("{:.0e}", -3.5f64));
+    assert_eq!("-4e0", format!("{:.0e}", -4.5f64));
+    assert_eq!("-6e0", format!("{:.0e}", -5.5f64));
+    assert_eq!("-1.28e2", format!("{:.2e}", -127.5f64));
+    assert_eq!("-1.28e2", format!("{:.2e}", -128.5f64));
+
+    assert_eq!("2E0", format!("{:.0E}", 1.5f64));
+    assert_eq!("2E0", format!("{:.0E}", 2.5f64));
+    assert_eq!("4E0", format!("{:.0E}", 3.5f64));
+    assert_eq!("4E0", format!("{:.0E}", 4.5f64));
+    assert_eq!("6E0", format!("{:.0E}", 5.5f64));
+    assert_eq!("1.28E2", format!("{:.2E}", 127.5f64));
+    assert_eq!("1.28E2", format!("{:.2E}", 128.5f64));
+    assert_eq!("-2E0", format!("{:.0E}", -1.5f64));
+    assert_eq!("-2E0", format!("{:.0E}", -2.5f64));
+    assert_eq!("-4E0", format!("{:.0E}", -3.5f64));
+    assert_eq!("-4E0", format!("{:.0E}", -4.5f64));
+    assert_eq!("-6E0", format!("{:.0E}", -5.5f64));
+    assert_eq!("-1.28E2", format!("{:.2E}", -127.5f64));
+    assert_eq!("-1.28E2", format!("{:.2E}", -128.5f64));
+}
+
+#[test]
 fn test_format_f32() {
     assert_eq!("1", format!("{:.0}", 1.0f32));
     assert_eq!("9", format!("{:.0}", 9.4f32));
@@ -50,6 +110,66 @@ fn test_format_f32() {
     assert_eq!("1234.6", format!("{:.1?}", 1234.56789f32));
 }
 
+#[test]
+fn test_format_f32_rounds_ties_to_even() {
+    assert_eq!("0", format!("{:.0}", 0.5f32));
+    assert_eq!("2", format!("{:.0}", 1.5f32));
+    assert_eq!("2", format!("{:.0}", 2.5f32));
+    assert_eq!("4", format!("{:.0}", 3.5f32));
+    assert_eq!("4", format!("{:.0}", 4.5f32));
+    assert_eq!("6", format!("{:.0}", 5.5f32));
+    assert_eq!("128", format!("{:.0}", 127.5f32));
+    assert_eq!("128", format!("{:.0}", 128.5f32));
+    assert_eq!("0.2", format!("{:.1}", 0.25f32));
+    assert_eq!("0.8", format!("{:.1}", 0.75f32));
+    assert_eq!("0.12", format!("{:.2}", 0.125f32));
+    assert_eq!("0.88", format!("{:.2}", 0.875f32));
+    assert_eq!("0.062", format!("{:.3}", 0.062f32));
+    assert_eq!("-0", format!("{:.0}", -0.5f32));
+    assert_eq!("-2", format!("{:.0}", -1.5f32));
+    assert_eq!("-2", format!("{:.0}", -2.5f32));
+    assert_eq!("-4", format!("{:.0}", -3.5f32));
+    assert_eq!("-4", format!("{:.0}", -4.5f32));
+    assert_eq!("-6", format!("{:.0}", -5.5f32));
+    assert_eq!("-128", format!("{:.0}", -127.5f32));
+    assert_eq!("-128", format!("{:.0}", -128.5f32));
+    assert_eq!("-0.2", format!("{:.1}", -0.25f32));
+    assert_eq!("-0.8", format!("{:.1}", -0.75f32));
+    assert_eq!("-0.12", format!("{:.2}", -0.125f32));
+    assert_eq!("-0.88", format!("{:.2}", -0.875f32));
+    assert_eq!("-0.062", format!("{:.3}", -0.062f32));
+
+    assert_eq!("2e0", format!("{:.0e}", 1.5f32));
+    assert_eq!("2e0", format!("{:.0e}", 2.5f32));
+    assert_eq!("4e0", format!("{:.0e}", 3.5f32));
+    assert_eq!("4e0", format!("{:.0e}", 4.5f32));
+    assert_eq!("6e0", format!("{:.0e}", 5.5f32));
+    assert_eq!("1.28e2", format!("{:.2e}", 127.5f32));
+    assert_eq!("1.28e2", format!("{:.2e}", 128.5f32));
+    assert_eq!("-2e0", format!("{:.0e}", -1.5f32));
+    assert_eq!("-2e0", format!("{:.0e}", -2.5f32));
+    assert_eq!("-4e0", format!("{:.0e}", -3.5f32));
+    assert_eq!("-4e0", format!("{:.0e}", -4.5f32));
+    assert_eq!("-6e0", format!("{:.0e}", -5.5f32));
+    assert_eq!("-1.28e2", format!("{:.2e}", -127.5f32));
+    assert_eq!("-1.28e2", format!("{:.2e}", -128.5f32));
+
+    assert_eq!("2E0", format!("{:.0E}", 1.5f32));
+    assert_eq!("2E0", format!("{:.0E}", 2.5f32));
+    assert_eq!("4E0", format!("{:.0E}", 3.5f32));
+    assert_eq!("4E0", format!("{:.0E}", 4.5f32));
+    assert_eq!("6E0", format!("{:.0E}", 5.5f32));
+    assert_eq!("1.28E2", format!("{:.2E}", 127.5f32));
+    assert_eq!("1.28E2", format!("{:.2E}", 128.5f32));
+    assert_eq!("-2E0", format!("{:.0E}", -1.5f32));
+    assert_eq!("-2E0", format!("{:.0E}", -2.5f32));
+    assert_eq!("-4E0", format!("{:.0E}", -3.5f32));
+    assert_eq!("-4E0", format!("{:.0E}", -4.5f32));
+    assert_eq!("-6E0", format!("{:.0E}", -5.5f32));
+    assert_eq!("-1.28E2", format!("{:.2E}", -127.5f32));
+    assert_eq!("-1.28E2", format!("{:.2E}", -128.5f32));
+}
+
 fn is_exponential(s: &str) -> bool {
     s.contains("e") || s.contains("E")
 }