From 698f8c2f01ea549d77d7dc3338a12e04c11057b9 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Wed, 17 Apr 2024 14:02:58 +0200
Subject: Adding upstream version 1.64.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 library/core/tests/fmt/builders.rs | 726 +++++++++++++++++++++++++++++++++++++
 library/core/tests/fmt/float.rs    |  55 +++
 library/core/tests/fmt/mod.rs      |  45 +++
 library/core/tests/fmt/num.rs      | 225 ++++++++++++
 4 files changed, 1051 insertions(+)
 create mode 100644 library/core/tests/fmt/builders.rs
 create mode 100644 library/core/tests/fmt/float.rs
 create mode 100644 library/core/tests/fmt/mod.rs
 create mode 100644 library/core/tests/fmt/num.rs

(limited to 'library/core/tests/fmt')

diff --git a/library/core/tests/fmt/builders.rs b/library/core/tests/fmt/builders.rs
new file mode 100644
index 000000000..487ce46be
--- /dev/null
+++ b/library/core/tests/fmt/builders.rs
@@ -0,0 +1,726 @@
+mod debug_struct {
+    use std::fmt;
+
+    #[test]
+    fn test_empty() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_struct("Foo").finish()
+            }
+        }
+
+        assert_eq!("Foo", format!("{Foo:?}"));
+        assert_eq!("Foo", format!("{Foo:#?}"));
+    }
+
+    #[test]
+    fn test_single() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_struct("Foo").field("bar", &true).finish()
+            }
+        }
+
+        assert_eq!("Foo { bar: true }", format!("{Foo:?}"));
+        assert_eq!(
+            "Foo {
+    bar: true,
+}",
+            format!("{Foo:#?}")
+        );
+    }
+
+    #[test]
+    fn test_multiple() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_struct("Foo")
+                    .field("bar", &true)
+                    .field("baz", &format_args!("{}/{}", 10, 20))
+                    .finish()
+            }
+        }
+
+        assert_eq!("Foo { bar: true, baz: 10/20 }", format!("{Foo:?}"));
+        assert_eq!(
+            "Foo {
+    bar: true,
+    baz: 10/20,
+}",
+            format!("{Foo:#?}")
+        );
+    }
+
+    #[test]
+    fn test_nested() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_struct("Foo")
+                    .field("bar", &true)
+                    .field("baz", &format_args!("{}/{}", 10, 20))
+                    .finish()
+            }
+        }
+
+        struct Bar;
+
+        impl fmt::Debug for Bar {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_struct("Bar").field("foo", &Foo).field("hello", &"world").finish()
+            }
+        }
+
+        assert_eq!(
+            "Bar { foo: Foo { bar: true, baz: 10/20 }, hello: \"world\" }",
+            format!("{Bar:?}")
+        );
+        assert_eq!(
+            "Bar {
+    foo: Foo {
+        bar: true,
+        baz: 10/20,
+    },
+    hello: \"world\",
+}",
+            format!("{Bar:#?}")
+        );
+    }
+
+    #[test]
+    fn test_only_non_exhaustive() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_struct("Foo").finish_non_exhaustive()
+            }
+        }
+
+        assert_eq!("Foo { .. }", format!("{Foo:?}"));
+        assert_eq!("Foo { .. }", format!("{Foo:#?}"));
+    }
+
+    #[test]
+    fn test_multiple_and_non_exhaustive() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_struct("Foo")
+                    .field("bar", &true)
+                    .field("baz", &format_args!("{}/{}", 10, 20))
+                    .finish_non_exhaustive()
+            }
+        }
+
+        assert_eq!("Foo { bar: true, baz: 10/20, .. }", format!("{Foo:?}"));
+        assert_eq!(
+            "Foo {
+    bar: true,
+    baz: 10/20,
+    ..
+}",
+            format!("{Foo:#?}")
+        );
+    }
+
+    #[test]
+    fn test_nested_non_exhaustive() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_struct("Foo")
+                    .field("bar", &true)
+                    .field("baz", &format_args!("{}/{}", 10, 20))
+                    .finish_non_exhaustive()
+            }
+        }
+
+        struct Bar;
+
+        impl fmt::Debug for Bar {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_struct("Bar")
+                    .field("foo", &Foo)
+                    .field("hello", &"world")
+                    .finish_non_exhaustive()
+            }
+        }
+
+        assert_eq!(
+            "Bar { foo: Foo { bar: true, baz: 10/20, .. }, hello: \"world\", .. }",
+            format!("{Bar:?}")
+        );
+        assert_eq!(
+            "Bar {
+    foo: Foo {
+        bar: true,
+        baz: 10/20,
+        ..
+    },
+    hello: \"world\",
+    ..
+}",
+            format!("{Bar:#?}")
+        );
+    }
+}
+
+mod debug_tuple {
+    use std::fmt;
+
+    #[test]
+    fn test_empty() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_tuple("Foo").finish()
+            }
+        }
+
+        assert_eq!("Foo", format!("{Foo:?}"));
+        assert_eq!("Foo", format!("{Foo:#?}"));
+    }
+
+    #[test]
+    fn test_single() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_tuple("Foo").field(&true).finish()
+            }
+        }
+
+        assert_eq!("Foo(true)", format!("{Foo:?}"));
+        assert_eq!(
+            "Foo(
+    true,
+)",
+            format!("{Foo:#?}")
+        );
+    }
+
+    #[test]
+    fn test_multiple() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_tuple("Foo").field(&true).field(&format_args!("{}/{}", 10, 20)).finish()
+            }
+        }
+
+        assert_eq!("Foo(true, 10/20)", format!("{Foo:?}"));
+        assert_eq!(
+            "Foo(
+    true,
+    10/20,
+)",
+            format!("{Foo:#?}")
+        );
+    }
+
+    #[test]
+    fn test_nested() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_tuple("Foo").field(&true).field(&format_args!("{}/{}", 10, 20)).finish()
+            }
+        }
+
+        struct Bar;
+
+        impl fmt::Debug for Bar {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_tuple("Bar").field(&Foo).field(&"world").finish()
+            }
+        }
+
+        assert_eq!("Bar(Foo(true, 10/20), \"world\")", format!("{Bar:?}"));
+        assert_eq!(
+            "Bar(
+    Foo(
+        true,
+        10/20,
+    ),
+    \"world\",
+)",
+            format!("{Bar:#?}")
+        );
+    }
+}
+
+mod debug_map {
+    use std::fmt;
+
+    #[test]
+    fn test_empty() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_map().finish()
+            }
+        }
+
+        assert_eq!("{}", format!("{Foo:?}"));
+        assert_eq!("{}", format!("{Foo:#?}"));
+    }
+
+    #[test]
+    fn test_single() {
+        struct Entry;
+
+        impl fmt::Debug for Entry {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_map().entry(&"bar", &true).finish()
+            }
+        }
+
+        struct KeyValue;
+
+        impl fmt::Debug for KeyValue {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_map().key(&"bar").value(&true).finish()
+            }
+        }
+
+        assert_eq!(format!("{Entry:?}"), format!("{KeyValue:?}"));
+        assert_eq!(format!("{Entry:#?}"), format!("{KeyValue:#?}"));
+
+        assert_eq!("{\"bar\": true}", format!("{Entry:?}"));
+        assert_eq!(
+            "{
+    \"bar\": true,
+}",
+            format!("{Entry:#?}")
+        );
+    }
+
+    #[test]
+    fn test_multiple() {
+        struct Entry;
+
+        impl fmt::Debug for Entry {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_map()
+                    .entry(&"bar", &true)
+                    .entry(&10, &format_args!("{}/{}", 10, 20))
+                    .finish()
+            }
+        }
+
+        struct KeyValue;
+
+        impl fmt::Debug for KeyValue {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_map()
+                    .key(&"bar")
+                    .value(&true)
+                    .key(&10)
+                    .value(&format_args!("{}/{}", 10, 20))
+                    .finish()
+            }
+        }
+
+        assert_eq!(format!("{Entry:?}"), format!("{KeyValue:?}"));
+        assert_eq!(format!("{Entry:#?}"), format!("{KeyValue:#?}"));
+
+        assert_eq!("{\"bar\": true, 10: 10/20}", format!("{Entry:?}"));
+        assert_eq!(
+            "{
+    \"bar\": true,
+    10: 10/20,
+}",
+            format!("{Entry:#?}")
+        );
+    }
+
+    #[test]
+    fn test_nested() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_map()
+                    .entry(&"bar", &true)
+                    .entry(&10, &format_args!("{}/{}", 10, 20))
+                    .finish()
+            }
+        }
+
+        struct Bar;
+
+        impl fmt::Debug for Bar {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_map().entry(&"foo", &Foo).entry(&Foo, &"world").finish()
+            }
+        }
+
+        assert_eq!(
+            "{\"foo\": {\"bar\": true, 10: 10/20}, \
+                    {\"bar\": true, 10: 10/20}: \"world\"}",
+            format!("{Bar:?}")
+        );
+        assert_eq!(
+            "{
+    \"foo\": {
+        \"bar\": true,
+        10: 10/20,
+    },
+    {
+        \"bar\": true,
+        10: 10/20,
+    }: \"world\",
+}",
+            format!("{Bar:#?}")
+        );
+    }
+
+    #[test]
+    fn test_entry_err() {
+        // Ensure errors in a map entry don't trigger panics (#65231)
+        use std::fmt::Write;
+
+        struct ErrorFmt;
+
+        impl fmt::Debug for ErrorFmt {
+            fn fmt(&self, _: &mut fmt::Formatter<'_>) -> fmt::Result {
+                Err(fmt::Error)
+            }
+        }
+
+        struct KeyValue<K, V>(usize, K, V);
+
+        impl<K, V> fmt::Debug for KeyValue<K, V>
+        where
+            K: fmt::Debug,
+            V: fmt::Debug,
+        {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                let mut map = fmt.debug_map();
+
+                for _ in 0..self.0 {
+                    map.entry(&self.1, &self.2);
+                }
+
+                map.finish()
+            }
+        }
+
+        let mut buf = String::new();
+
+        assert!(write!(&mut buf, "{:?}", KeyValue(1, ErrorFmt, "bar")).is_err());
+        assert!(write!(&mut buf, "{:?}", KeyValue(1, "foo", ErrorFmt)).is_err());
+
+        assert!(write!(&mut buf, "{:?}", KeyValue(2, ErrorFmt, "bar")).is_err());
+        assert!(write!(&mut buf, "{:?}", KeyValue(2, "foo", ErrorFmt)).is_err());
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_invalid_key_when_entry_is_incomplete() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_map().key(&"bar").key(&"invalid").finish()
+            }
+        }
+
+        format!("{Foo:?}");
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_invalid_finish_incomplete_entry() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_map().key(&"bar").finish()
+            }
+        }
+
+        format!("{Foo:?}");
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_invalid_value_before_key() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_map().value(&"invalid").key(&"bar").finish()
+            }
+        }
+
+        format!("{Foo:?}");
+    }
+}
+
+mod debug_set {
+    use std::fmt;
+
+    #[test]
+    fn test_empty() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_set().finish()
+            }
+        }
+
+        assert_eq!("{}", format!("{Foo:?}"));
+        assert_eq!("{}", format!("{Foo:#?}"));
+    }
+
+    #[test]
+    fn test_single() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_set().entry(&true).finish()
+            }
+        }
+
+        assert_eq!("{true}", format!("{Foo:?}"));
+        assert_eq!(
+            "{
+    true,
+}",
+            format!("{Foo:#?}")
+        );
+    }
+
+    #[test]
+    fn test_multiple() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_set().entry(&true).entry(&format_args!("{}/{}", 10, 20)).finish()
+            }
+        }
+
+        assert_eq!("{true, 10/20}", format!("{Foo:?}"));
+        assert_eq!(
+            "{
+    true,
+    10/20,
+}",
+            format!("{Foo:#?}")
+        );
+    }
+
+    #[test]
+    fn test_nested() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_set().entry(&true).entry(&format_args!("{}/{}", 10, 20)).finish()
+            }
+        }
+
+        struct Bar;
+
+        impl fmt::Debug for Bar {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_set().entry(&Foo).entry(&"world").finish()
+            }
+        }
+
+        assert_eq!("{{true, 10/20}, \"world\"}", format!("{Bar:?}"));
+        assert_eq!(
+            "{
+    {
+        true,
+        10/20,
+    },
+    \"world\",
+}",
+            format!("{Bar:#?}")
+        );
+    }
+}
+
+mod debug_list {
+    use std::fmt;
+
+    #[test]
+    fn test_empty() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_list().finish()
+            }
+        }
+
+        assert_eq!("[]", format!("{Foo:?}"));
+        assert_eq!("[]", format!("{Foo:#?}"));
+    }
+
+    #[test]
+    fn test_single() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_list().entry(&true).finish()
+            }
+        }
+
+        assert_eq!("[true]", format!("{Foo:?}"));
+        assert_eq!(
+            "[
+    true,
+]",
+            format!("{Foo:#?}")
+        );
+    }
+
+    #[test]
+    fn test_multiple() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_list().entry(&true).entry(&format_args!("{}/{}", 10, 20)).finish()
+            }
+        }
+
+        assert_eq!("[true, 10/20]", format!("{Foo:?}"));
+        assert_eq!(
+            "[
+    true,
+    10/20,
+]",
+            format!("{Foo:#?}")
+        );
+    }
+
+    #[test]
+    fn test_nested() {
+        struct Foo;
+
+        impl fmt::Debug for Foo {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_list().entry(&true).entry(&format_args!("{}/{}", 10, 20)).finish()
+            }
+        }
+
+        struct Bar;
+
+        impl fmt::Debug for Bar {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_list().entry(&Foo).entry(&"world").finish()
+            }
+        }
+
+        assert_eq!("[[true, 10/20], \"world\"]", format!("{Bar:?}"));
+        assert_eq!(
+            "[
+    [
+        true,
+        10/20,
+    ],
+    \"world\",
+]",
+            format!("{Bar:#?}")
+        );
+    }
+}
+
+#[test]
+fn test_formatting_parameters_are_forwarded() {
+    use std::collections::{BTreeMap, BTreeSet};
+    #[derive(Debug)]
+    #[allow(dead_code)]
+    struct Foo {
+        bar: u32,
+        baz: u32,
+    }
+    let struct_ = Foo { bar: 1024, baz: 7 };
+    let tuple = (1024, 7);
+    let list = [1024, 7];
+    let mut map = BTreeMap::new();
+    map.insert("bar", 1024);
+    map.insert("baz", 7);
+    let mut set = BTreeSet::new();
+    set.insert(1024);
+    set.insert(7);
+
+    assert_eq!(format!("{struct_:03?}"), "Foo { bar: 1024, baz: 007 }");
+    assert_eq!(format!("{tuple:03?}"), "(1024, 007)");
+    assert_eq!(format!("{list:03?}"), "[1024, 007]");
+    assert_eq!(format!("{map:03?}"), r#"{"bar": 1024, "baz": 007}"#);
+    assert_eq!(format!("{set:03?}"), "{007, 1024}");
+    assert_eq!(
+        format!("{struct_:#03?}"),
+        "
+Foo {
+    bar: 1024,
+    baz: 007,
+}
+    "
+        .trim()
+    );
+    assert_eq!(
+        format!("{tuple:#03?}"),
+        "
+(
+    1024,
+    007,
+)
+    "
+        .trim()
+    );
+    assert_eq!(
+        format!("{list:#03?}"),
+        "
+[
+    1024,
+    007,
+]
+    "
+        .trim()
+    );
+    assert_eq!(
+        format!("{map:#03?}"),
+        r#"
+{
+    "bar": 1024,
+    "baz": 007,
+}
+    "#
+        .trim()
+    );
+    assert_eq!(
+        format!("{set:#03?}"),
+        "
+{
+    007,
+    1024,
+}
+    "
+        .trim()
+    );
+}
diff --git a/library/core/tests/fmt/float.rs b/library/core/tests/fmt/float.rs
new file mode 100644
index 000000000..47a7400f7
--- /dev/null
+++ b/library/core/tests/fmt/float.rs
@@ -0,0 +1,55 @@
+#[test]
+fn test_format_f64() {
+    assert_eq!("1", format!("{:.0}", 1.0f64));
+    assert_eq!("9", format!("{:.0}", 9.4f64));
+    assert_eq!("10", format!("{:.0}", 9.9f64));
+    assert_eq!("9.8", format!("{:.1}", 9.849f64));
+    assert_eq!("9.9", format!("{:.1}", 9.851f64));
+    assert_eq!("1", format!("{:.0}", 0.5f64));
+    assert_eq!("1.23456789e6", format!("{:e}", 1234567.89f64));
+    assert_eq!("1.23456789e3", format!("{:e}", 1234.56789f64));
+    assert_eq!("1.23456789E6", format!("{:E}", 1234567.89f64));
+    assert_eq!("1.23456789E3", format!("{:E}", 1234.56789f64));
+    assert_eq!("0.0", format!("{:?}", 0.0f64));
+    assert_eq!("1.01", format!("{:?}", 1.01f64));
+
+    let high_cutoff = 1e16_f64;
+    assert_eq!("1e16", format!("{:?}", high_cutoff));
+    assert_eq!("-1e16", format!("{:?}", -high_cutoff));
+    assert!(!is_exponential(&format!("{:?}", high_cutoff * (1.0 - 2.0 * f64::EPSILON))));
+    assert_eq!("-3.0", format!("{:?}", -3f64));
+    assert_eq!("0.0001", format!("{:?}", 0.0001f64));
+    assert_eq!("9e-5", format!("{:?}", 0.00009f64));
+    assert_eq!("1234567.9", format!("{:.1?}", 1234567.89f64));
+    assert_eq!("1234.6", format!("{:.1?}", 1234.56789f64));
+}
+
+#[test]
+fn test_format_f32() {
+    assert_eq!("1", format!("{:.0}", 1.0f32));
+    assert_eq!("9", format!("{:.0}", 9.4f32));
+    assert_eq!("10", format!("{:.0}", 9.9f32));
+    assert_eq!("9.8", format!("{:.1}", 9.849f32));
+    assert_eq!("9.9", format!("{:.1}", 9.851f32));
+    assert_eq!("1", format!("{:.0}", 0.5f32));
+    assert_eq!("1.2345679e6", format!("{:e}", 1234567.89f32));
+    assert_eq!("1.2345679e3", format!("{:e}", 1234.56789f32));
+    assert_eq!("1.2345679E6", format!("{:E}", 1234567.89f32));
+    assert_eq!("1.2345679E3", format!("{:E}", 1234.56789f32));
+    assert_eq!("0.0", format!("{:?}", 0.0f32));
+    assert_eq!("1.01", format!("{:?}", 1.01f32));
+
+    let high_cutoff = 1e16_f32;
+    assert_eq!("1e16", format!("{:?}", high_cutoff));
+    assert_eq!("-1e16", format!("{:?}", -high_cutoff));
+    assert!(!is_exponential(&format!("{:?}", high_cutoff * (1.0 - 2.0 * f32::EPSILON))));
+    assert_eq!("-3.0", format!("{:?}", -3f32));
+    assert_eq!("0.0001", format!("{:?}", 0.0001f32));
+    assert_eq!("9e-5", format!("{:?}", 0.00009f32));
+    assert_eq!("1234567.9", format!("{:.1?}", 1234567.89f32));
+    assert_eq!("1234.6", format!("{:.1?}", 1234.56789f32));
+}
+
+fn is_exponential(s: &str) -> bool {
+    s.contains("e") || s.contains("E")
+}
diff --git a/library/core/tests/fmt/mod.rs b/library/core/tests/fmt/mod.rs
new file mode 100644
index 000000000..618076358
--- /dev/null
+++ b/library/core/tests/fmt/mod.rs
@@ -0,0 +1,45 @@
+mod builders;
+mod float;
+mod num;
+
+#[test]
+fn test_format_flags() {
+    // No residual flags left by pointer formatting
+    let p = "".as_ptr();
+    assert_eq!(format!("{:p} {:x}", p, 16), format!("{p:p} 10"));
+
+    assert_eq!(format!("{: >3}", 'a'), "  a");
+}
+
+#[test]
+fn test_pointer_formats_data_pointer() {
+    let b: &[u8] = b"";
+    let s: &str = "";
+    assert_eq!(format!("{s:p}"), format!("{:p}", s.as_ptr()));
+    assert_eq!(format!("{b:p}"), format!("{:p}", b.as_ptr()));
+}
+
+#[test]
+fn test_estimated_capacity() {
+    assert_eq!(format_args!("").estimated_capacity(), 0);
+    assert_eq!(format_args!("{}", "").estimated_capacity(), 0);
+    assert_eq!(format_args!("Hello").estimated_capacity(), 5);
+    assert_eq!(format_args!("Hello, {}!", "").estimated_capacity(), 16);
+    assert_eq!(format_args!("{}, hello!", "World").estimated_capacity(), 0);
+    assert_eq!(format_args!("{}. 16-bytes piece", "World").estimated_capacity(), 32);
+}
+
+#[test]
+fn pad_integral_resets() {
+    struct Bar;
+
+    impl core::fmt::Display for Bar {
+        fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+            "1".fmt(f)?;
+            f.pad_integral(true, "", "5")?;
+            "1".fmt(f)
+        }
+    }
+
+    assert_eq!(format!("{Bar:<03}"), "1  0051  ");
+}
diff --git a/library/core/tests/fmt/num.rs b/library/core/tests/fmt/num.rs
new file mode 100644
index 000000000..b9ede65c9
--- /dev/null
+++ b/library/core/tests/fmt/num.rs
@@ -0,0 +1,225 @@
+#[test]
+fn test_format_int() {
+    // Formatting integers should select the right implementation based off
+    // the type of the argument. Also, hex/octal/binary should be defined
+    // for integers, but they shouldn't emit the negative sign.
+    assert_eq!(format!("{}", 1isize), "1");
+    assert_eq!(format!("{}", 1i8), "1");
+    assert_eq!(format!("{}", 1i16), "1");
+    assert_eq!(format!("{}", 1i32), "1");
+    assert_eq!(format!("{}", 1i64), "1");
+    assert_eq!(format!("{}", -1isize), "-1");
+    assert_eq!(format!("{}", -1i8), "-1");
+    assert_eq!(format!("{}", -1i16), "-1");
+    assert_eq!(format!("{}", -1i32), "-1");
+    assert_eq!(format!("{}", -1i64), "-1");
+    assert_eq!(format!("{:?}", 1isize), "1");
+    assert_eq!(format!("{:?}", 1i8), "1");
+    assert_eq!(format!("{:?}", 1i16), "1");
+    assert_eq!(format!("{:?}", 1i32), "1");
+    assert_eq!(format!("{:?}", 1i64), "1");
+    assert_eq!(format!("{:b}", 1isize), "1");
+    assert_eq!(format!("{:b}", 1i8), "1");
+    assert_eq!(format!("{:b}", 1i16), "1");
+    assert_eq!(format!("{:b}", 1i32), "1");
+    assert_eq!(format!("{:b}", 1i64), "1");
+    assert_eq!(format!("{:x}", 1isize), "1");
+    assert_eq!(format!("{:x}", 1i8), "1");
+    assert_eq!(format!("{:x}", 1i16), "1");
+    assert_eq!(format!("{:x}", 1i32), "1");
+    assert_eq!(format!("{:x}", 1i64), "1");
+    assert_eq!(format!("{:X}", 1isize), "1");
+    assert_eq!(format!("{:X}", 1i8), "1");
+    assert_eq!(format!("{:X}", 1i16), "1");
+    assert_eq!(format!("{:X}", 1i32), "1");
+    assert_eq!(format!("{:X}", 1i64), "1");
+    assert_eq!(format!("{:o}", 1isize), "1");
+    assert_eq!(format!("{:o}", 1i8), "1");
+    assert_eq!(format!("{:o}", 1i16), "1");
+    assert_eq!(format!("{:o}", 1i32), "1");
+    assert_eq!(format!("{:o}", 1i64), "1");
+    assert_eq!(format!("{:e}", 1isize), "1e0");
+    assert_eq!(format!("{:e}", 1i8), "1e0");
+    assert_eq!(format!("{:e}", 1i16), "1e0");
+    assert_eq!(format!("{:e}", 1i32), "1e0");
+    assert_eq!(format!("{:e}", 1i64), "1e0");
+    assert_eq!(format!("{:E}", 1isize), "1E0");
+    assert_eq!(format!("{:E}", 1i8), "1E0");
+    assert_eq!(format!("{:E}", 1i16), "1E0");
+    assert_eq!(format!("{:E}", 1i32), "1E0");
+    assert_eq!(format!("{:E}", 1i64), "1E0");
+
+    assert_eq!(format!("{}", 1usize), "1");
+    assert_eq!(format!("{}", 1u8), "1");
+    assert_eq!(format!("{}", 1u16), "1");
+    assert_eq!(format!("{}", 1u32), "1");
+    assert_eq!(format!("{}", 1u64), "1");
+    assert_eq!(format!("{:?}", 1usize), "1");
+    assert_eq!(format!("{:?}", 1u8), "1");
+    assert_eq!(format!("{:?}", 1u16), "1");
+    assert_eq!(format!("{:?}", 1u32), "1");
+    assert_eq!(format!("{:?}", 1u64), "1");
+    assert_eq!(format!("{:b}", 1usize), "1");
+    assert_eq!(format!("{:b}", 1u8), "1");
+    assert_eq!(format!("{:b}", 1u16), "1");
+    assert_eq!(format!("{:b}", 1u32), "1");
+    assert_eq!(format!("{:b}", 1u64), "1");
+    assert_eq!(format!("{:x}", 1usize), "1");
+    assert_eq!(format!("{:x}", 1u8), "1");
+    assert_eq!(format!("{:x}", 1u16), "1");
+    assert_eq!(format!("{:x}", 1u32), "1");
+    assert_eq!(format!("{:x}", 1u64), "1");
+    assert_eq!(format!("{:X}", 1usize), "1");
+    assert_eq!(format!("{:X}", 1u8), "1");
+    assert_eq!(format!("{:X}", 1u16), "1");
+    assert_eq!(format!("{:X}", 1u32), "1");
+    assert_eq!(format!("{:X}", 1u64), "1");
+    assert_eq!(format!("{:o}", 1usize), "1");
+    assert_eq!(format!("{:o}", 1u8), "1");
+    assert_eq!(format!("{:o}", 1u16), "1");
+    assert_eq!(format!("{:o}", 1u32), "1");
+    assert_eq!(format!("{:o}", 1u64), "1");
+    assert_eq!(format!("{:e}", 1u8), "1e0");
+    assert_eq!(format!("{:e}", 1u16), "1e0");
+    assert_eq!(format!("{:e}", 1u32), "1e0");
+    assert_eq!(format!("{:e}", 1u64), "1e0");
+    assert_eq!(format!("{:E}", 1u8), "1E0");
+    assert_eq!(format!("{:E}", 1u16), "1E0");
+    assert_eq!(format!("{:E}", 1u32), "1E0");
+    assert_eq!(format!("{:E}", 1u64), "1E0");
+
+    // Test a larger number
+    assert_eq!(format!("{:b}", 55), "110111");
+    assert_eq!(format!("{:o}", 55), "67");
+    assert_eq!(format!("{}", 55), "55");
+    assert_eq!(format!("{:x}", 55), "37");
+    assert_eq!(format!("{:X}", 55), "37");
+    assert_eq!(format!("{:e}", 55), "5.5e1");
+    assert_eq!(format!("{:E}", 55), "5.5E1");
+    assert_eq!(format!("{:e}", 10000000000u64), "1e10");
+    assert_eq!(format!("{:E}", 10000000000u64), "1E10");
+    assert_eq!(format!("{:e}", 10000000001u64), "1.0000000001e10");
+    assert_eq!(format!("{:E}", 10000000001u64), "1.0000000001E10");
+}
+
+#[test]
+fn test_format_int_exp_limits() {
+    assert_eq!(format!("{:e}", i8::MIN), "-1.28e2");
+    assert_eq!(format!("{:e}", i8::MAX), "1.27e2");
+    assert_eq!(format!("{:e}", i16::MIN), "-3.2768e4");
+    assert_eq!(format!("{:e}", i16::MAX), "3.2767e4");
+    assert_eq!(format!("{:e}", i32::MIN), "-2.147483648e9");
+    assert_eq!(format!("{:e}", i32::MAX), "2.147483647e9");
+    assert_eq!(format!("{:e}", i64::MIN), "-9.223372036854775808e18");
+    assert_eq!(format!("{:e}", i64::MAX), "9.223372036854775807e18");
+    assert_eq!(format!("{:e}", i128::MIN), "-1.70141183460469231731687303715884105728e38");
+    assert_eq!(format!("{:e}", i128::MAX), "1.70141183460469231731687303715884105727e38");
+
+    assert_eq!(format!("{:e}", u8::MAX), "2.55e2");
+    assert_eq!(format!("{:e}", u16::MAX), "6.5535e4");
+    assert_eq!(format!("{:e}", u32::MAX), "4.294967295e9");
+    assert_eq!(format!("{:e}", u64::MAX), "1.8446744073709551615e19");
+    assert_eq!(format!("{:e}", u128::MAX), "3.40282366920938463463374607431768211455e38");
+}
+
+#[test]
+fn test_format_int_exp_precision() {
+    //test that float and integer match
+    let big_int: u32 = 314_159_265;
+    assert_eq!(format!("{big_int:.1e}"), format!("{:.1e}", f64::from(big_int)));
+
+    //test adding precision
+    assert_eq!(format!("{:.10e}", i8::MIN), "-1.2800000000e2");
+    assert_eq!(format!("{:.10e}", i16::MIN), "-3.2768000000e4");
+    assert_eq!(format!("{:.10e}", i32::MIN), "-2.1474836480e9");
+    assert_eq!(format!("{:.20e}", i64::MIN), "-9.22337203685477580800e18");
+    assert_eq!(format!("{:.40e}", i128::MIN), "-1.7014118346046923173168730371588410572800e38");
+
+    //test rounding
+    assert_eq!(format!("{:.1e}", i8::MIN), "-1.3e2");
+    assert_eq!(format!("{:.1e}", i16::MIN), "-3.3e4");
+    assert_eq!(format!("{:.1e}", i32::MIN), "-2.1e9");
+    assert_eq!(format!("{:.1e}", i64::MIN), "-9.2e18");
+    assert_eq!(format!("{:.1e}", i128::MIN), "-1.7e38");
+
+    //test huge precision
+    assert_eq!(format!("{:.1000e}", 1), format!("1.{}e0", "0".repeat(1000)));
+    //test zero precision
+    assert_eq!(format!("{:.0e}", 1), format!("1e0",));
+    assert_eq!(format!("{:.0e}", 35), format!("4e1",));
+
+    //test padding with precision (and sign)
+    assert_eq!(format!("{:+10.3e}", 1), "  +1.000e0");
+}
+
+#[test]
+fn test_format_int_zero() {
+    assert_eq!(format!("{}", 0), "0");
+    assert_eq!(format!("{:?}", 0), "0");
+    assert_eq!(format!("{:b}", 0), "0");
+    assert_eq!(format!("{:o}", 0), "0");
+    assert_eq!(format!("{:x}", 0), "0");
+    assert_eq!(format!("{:X}", 0), "0");
+    assert_eq!(format!("{:e}", 0), "0e0");
+    assert_eq!(format!("{:E}", 0), "0E0");
+
+    assert_eq!(format!("{}", 0u32), "0");
+    assert_eq!(format!("{:?}", 0u32), "0");
+    assert_eq!(format!("{:b}", 0u32), "0");
+    assert_eq!(format!("{:o}", 0u32), "0");
+    assert_eq!(format!("{:x}", 0u32), "0");
+    assert_eq!(format!("{:X}", 0u32), "0");
+    assert_eq!(format!("{:e}", 0u32), "0e0");
+    assert_eq!(format!("{:E}", 0u32), "0E0");
+}
+
+#[test]
+fn test_format_int_flags() {
+    assert_eq!(format!("{:3}", 1), "  1");
+    assert_eq!(format!("{:>3}", 1), "  1");
+    assert_eq!(format!("{:>+3}", 1), " +1");
+    assert_eq!(format!("{:<3}", 1), "1  ");
+    assert_eq!(format!("{:#}", 1), "1");
+    assert_eq!(format!("{:#x}", 10), "0xa");
+    assert_eq!(format!("{:#X}", 10), "0xA");
+    assert_eq!(format!("{:#5x}", 10), "  0xa");
+    assert_eq!(format!("{:#o}", 10), "0o12");
+    assert_eq!(format!("{:08x}", 10), "0000000a");
+    assert_eq!(format!("{:8x}", 10), "       a");
+    assert_eq!(format!("{:<8x}", 10), "a       ");
+    assert_eq!(format!("{:>8x}", 10), "       a");
+    assert_eq!(format!("{:#08x}", 10), "0x00000a");
+    assert_eq!(format!("{:08}", -10), "-0000010");
+    assert_eq!(format!("{:x}", !0u8), "ff");
+    assert_eq!(format!("{:X}", !0u8), "FF");
+    assert_eq!(format!("{:b}", !0u8), "11111111");
+    assert_eq!(format!("{:o}", !0u8), "377");
+    assert_eq!(format!("{:#x}", !0u8), "0xff");
+    assert_eq!(format!("{:#X}", !0u8), "0xFF");
+    assert_eq!(format!("{:#b}", !0u8), "0b11111111");
+    assert_eq!(format!("{:#o}", !0u8), "0o377");
+}
+
+#[test]
+fn test_format_int_sign_padding() {
+    assert_eq!(format!("{:+5}", 1), "   +1");
+    assert_eq!(format!("{:+5}", -1), "   -1");
+    assert_eq!(format!("{:05}", 1), "00001");
+    assert_eq!(format!("{:05}", -1), "-0001");
+    assert_eq!(format!("{:+05}", 1), "+0001");
+    assert_eq!(format!("{:+05}", -1), "-0001");
+}
+
+#[test]
+fn test_format_int_twos_complement() {
+    assert_eq!(format!("{}", i8::MIN), "-128");
+    assert_eq!(format!("{}", i16::MIN), "-32768");
+    assert_eq!(format!("{}", i32::MIN), "-2147483648");
+    assert_eq!(format!("{}", i64::MIN), "-9223372036854775808");
+}
+
+#[test]
+fn test_format_debug_hex() {
+    assert_eq!(format!("{:02x?}", b"Foo\0"), "[46, 6f, 6f, 00]");
+    assert_eq!(format!("{:02X?}", b"Foo\0"), "[46, 6F, 6F, 00]");
+}
-- 
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