9 files changed, 543 insertions, 478 deletions

diff --git a/crates/ide_assists/src/handlers/apply_demorgan.rs b/crates/ide_assists/src/handlers/apply_demorgan.rs
index c93959e66..e2bd6e456 100644
--- a/crates/ide_assists/src/handlers/apply_demorgan.rs
+++ b/crates/ide_assists/src/handlers/apply_demorgan.rs
@@ -147,74 +147,92 @@ fn opposite_logic_op(kind: ast::BinOp) -> Option<&'static str> {
 
 #[cfg(test)]
 mod tests {
-    use ide_db::helpers::FamousDefs;
-
-    use super::*;
-
     use crate::tests::{check_assist, check_assist_not_applicable};
 
-    const ORDABLE_FIXTURE: &'static str = r"
-//- /lib.rs deps:core crate:ordable
-struct NonOrderable;
-struct Orderable;
-impl core::cmp::Ord for Orderable {}
-";
-
-    fn check(ra_fixture_before: &str, ra_fixture_after: &str) {
-        let before = &format!(
-            "//- /main.rs crate:main deps:core,ordable\n{}\n{}{}",
-            ra_fixture_before,
-            FamousDefs::FIXTURE,
-            ORDABLE_FIXTURE
-        );
-        check_assist(apply_demorgan, before, &format!("{}\n", ra_fixture_after));
-    }
+    use super::*;
 
     #[test]
     fn demorgan_handles_leq() {
-        check(
-            r"use ordable::Orderable;
+        check_assist(
+            apply_demorgan,
+            r#"
+//- minicore: ord, derive
+#[derive(PartialEq, Eq, PartialOrd, Ord)]
+struct S;
+
 fn f() {
-    Orderable < Orderable &&$0 Orderable <= Orderable
-}",
-            r"use ordable::Orderable;
+    S < S &&$0 S <= S
+}
+"#,
+            r#"
+#[derive(PartialEq, Eq, PartialOrd, Ord)]
+struct S;
+
 fn f() {
-    !(Orderable >= Orderable || Orderable > Orderable)
-}",
+    !(S >= S || S > S)
+}
+"#,
         );
-        check(
-            r"use ordable::NonOrderable;
+
+        check_assist(
+            apply_demorgan,
+            r#"
+//- minicore: ord, derive
+struct S;
+
 fn f() {
-    NonOrderable < NonOrderable &&$0 NonOrderable <= NonOrderable
-}",
-            r"use ordable::NonOrderable;
+    S < S &&$0 S <= S
+}
+"#,
+            r#"
+struct S;
+
 fn f() {
-    !(!(NonOrderable < NonOrderable) || !(NonOrderable <= NonOrderable))
-}",
+    !(!(S < S) || !(S <= S))
+}
+"#,
         );
     }
 
     #[test]
     fn demorgan_handles_geq() {
-        check(
-            r"use ordable::Orderable;
+        check_assist(
+            apply_demorgan,
+            r#"
+//- minicore: ord, derive
+#[derive(PartialEq, Eq, PartialOrd, Ord)]
+struct S;
+
 fn f() {
-    Orderable > Orderable &&$0 Orderable >= Orderable
-}",
-            r"use ordable::Orderable;
+    S > S &&$0 S >= S
+}
+"#,
+            r#"
+#[derive(PartialEq, Eq, PartialOrd, Ord)]
+struct S;
+
 fn f() {
-    !(Orderable <= Orderable || Orderable < Orderable)
-}",
+    !(S <= S || S < S)
+}
+"#,
         );
-        check(
-            r"use ordable::NonOrderable;
+        check_assist(
+            apply_demorgan,
+            r#"
+//- minicore: ord, derive
+struct S;
+
 fn f() {
-    Orderable > Orderable &&$0 Orderable >= Orderable
-}",
-            r"use ordable::NonOrderable;
+    S > S &&$0 S >= S
+}
+"#,
+            r#"
+struct S;
+
 fn f() {
-    !(!(Orderable > Orderable) || !(Orderable >= Orderable))
-}",
+    !(!(S > S) || !(S >= S))
+}
+"#,
         );
     }
 
diff --git a/crates/ide_assists/src/handlers/convert_into_to_from.rs b/crates/ide_assists/src/handlers/convert_into_to_from.rs
index 79a0c4879..2d8b936cd 100644
--- a/crates/ide_assists/src/handlers/convert_into_to_from.rs
+++ b/crates/ide_assists/src/handlers/convert_into_to_from.rs
@@ -13,10 +13,7 @@ use crate::{AssistContext, AssistId, AssistKind, Assists};
 // Converts an Into impl to an equivalent From impl.
 //
 // ```
-// # //- /lib.rs crate:core
-// # pub mod convert { pub trait Into<T> { pub fn into(self) -> T; } }
-// # //- /lib.rs crate:main deps:core
-// # use core::convert::Into;
+// # //- minicore: from
 // impl $0Into<Thing> for usize {
 //     fn into(self) -> Thing {
 //         Thing {
@@ -28,7 +25,6 @@ use crate::{AssistContext, AssistId, AssistKind, Assists};
 // ```
 // ->
 // ```
-// # use core::convert::Into;
 // impl From<usize> for Thing {
 //     fn from(val: usize) -> Self {
 //         Thing {
diff --git a/crates/ide_assists/src/handlers/convert_iter_for_each_to_for.rs b/crates/ide_assists/src/handlers/convert_iter_for_each_to_for.rs
index 7fd73d4c7..70754adf9 100644
--- a/crates/ide_assists/src/handlers/convert_iter_for_each_to_for.rs
+++ b/crates/ide_assists/src/handlers/convert_iter_for_each_to_for.rs
@@ -11,14 +11,10 @@ use crate::{AssistContext, AssistId, AssistKind, Assists};
 // Converts an Iterator::for_each function into a for loop.
 //
 // ```
-// # //- /lib.rs crate:core
-// # pub mod iter { pub mod traits { pub mod iterator { pub trait Iterator {} } } }
-// # pub struct SomeIter;
-// # impl self::iter::traits::iterator::Iterator for SomeIter {}
-// # //- /lib.rs crate:main deps:core
-// # use core::SomeIter;
+// # //- minicore: iterators
+// # use core::iter;
 // fn main() {
-//     let iter = SomeIter;
+//     let iter = iter::repeat((9, 2));
 //     iter.for_each$0(|(x, y)| {
 //         println!("x: {}, y: {}", x, y);
 //     });
@@ -26,9 +22,9 @@ use crate::{AssistContext, AssistId, AssistKind, Assists};
 // ```
 // ->
 // ```
-// # use core::SomeIter;
+// # use core::iter;
 // fn main() {
-//     let iter = SomeIter;
+//     let iter = iter::repeat((9, 2));
 //     for (x, y) in iter {
 //         println!("x: {}, y: {}", x, y);
 //     }
diff --git a/crates/ide_assists/src/handlers/extract_function.rs b/crates/ide_assists/src/handlers/extract_function.rs
index 7085a0c48..ac7f0959b 100644
--- a/crates/ide_assists/src/handlers/extract_function.rs
+++ b/crates/ide_assists/src/handlers/extract_function.rs
@@ -1501,7 +1501,8 @@ mod tests {
             r#"
 fn foo() {
     foo($01 + 1$0);
-}"#,
+}
+"#,
             r#"
 fn foo() {
     foo(fun_name());
@@ -1509,7 +1510,8 @@ fn foo() {
 
 fn $0fun_name() -> i32 {
     1 + 1
-}"#,
+}
+"#,
         );
     }
 
@@ -1522,7 +1524,8 @@ mod bar {
     fn foo() {
         foo($01 + 1$0);
     }
-}"#,
+}
+"#,
             r#"
 mod bar {
     fn foo() {
@@ -1532,7 +1535,8 @@ mod bar {
     fn $0fun_name() -> i32 {
         1 + 1
     }
-}"#,
+}
+"#,
         );
     }
 
@@ -1543,7 +1547,8 @@ mod bar {
             r#"
 fn foo() {
     $0{ 1 + 1 }$0;
-}"#,
+}
+"#,
             r#"
 fn foo() {
     fun_name();
@@ -1551,7 +1556,8 @@ fn foo() {
 
 fn $0fun_name() -> i32 {
     1 + 1
-}"#,
+}
+"#,
         );
     }
 
@@ -1564,7 +1570,8 @@ fn foo() -> i32 {
     let k = 1;
     $0let m = 1;
     m + 1$0
-}"#,
+}
+"#,
             r#"
 fn foo() -> i32 {
     let k = 1;
@@ -1574,7 +1581,8 @@ fn foo() -> i32 {
 fn $0fun_name() -> i32 {
     let m = 1;
     m + 1
-}"#,
+}
+"#,
         );
     }
 
@@ -1588,7 +1596,8 @@ fn foo() {
     $0let m = 1;
     let n = m + 1;$0
     let g = 5;
-}"#,
+}
+"#,
             r#"
 fn foo() {
     let k = 3;
@@ -1599,7 +1608,8 @@ fn foo() {
 fn $0fun_name() {
     let m = 1;
     let n = m + 1;
-}"#,
+}
+"#,
         );
     }
 
@@ -1610,7 +1620,8 @@ fn $0fun_name() {
             r#"
 fn foo() {
     $0if true { }$0
-}"#,
+}
+"#,
             r#"
 fn foo() {
     fun_name();
@@ -1618,7 +1629,8 @@ fn foo() {
 
 fn $0fun_name() {
     if true { }
-}"#,
+}
+"#,
         );
     }
 
@@ -1629,7 +1641,8 @@ fn $0fun_name() {
             r#"
 fn foo() -> i32 {
     $0if true { 1 } else { 2 }$0
-}"#,
+}
+"#,
             r#"
 fn foo() -> i32 {
     fun_name()
@@ -1637,7 +1650,8 @@ fn foo() -> i32 {
 
 fn $0fun_name() -> i32 {
     if true { 1 } else { 2 }
-}"#,
+}
+"#,
         );
     }
 
@@ -1648,7 +1662,8 @@ fn $0fun_name() -> i32 {
             r#"
 fn foo() -> i32 {
     $0if let true = false { 1 } else { 2 }$0
-}"#,
+}
+"#,
             r#"
 fn foo() -> i32 {
     fun_name()
@@ -1656,7 +1671,8 @@ fn foo() -> i32 {
 
 fn $0fun_name() -> i32 {
     if let true = false { 1 } else { 2 }
-}"#,
+}
+"#,
         );
     }
 
@@ -1670,7 +1686,8 @@ fn foo() -> i32 {
         true => 1,
         false => 2,
     }$0
-}"#,
+}
+"#,
             r#"
 fn foo() -> i32 {
     fun_name()
@@ -1681,7 +1698,8 @@ fn $0fun_name() -> i32 {
         true => 1,
         false => 2,
     }
-}"#,
+}
+"#,
         );
     }
 
@@ -1692,7 +1710,8 @@ fn $0fun_name() -> i32 {
             r#"
 fn foo() {
     $0while true { }$0
-}"#,
+}
+"#,
             r#"
 fn foo() {
     fun_name();
@@ -1700,7 +1719,8 @@ fn foo() {
 
 fn $0fun_name() {
     while true { }
-}"#,
+}
+"#,
         );
     }
 
@@ -1711,7 +1731,8 @@ fn $0fun_name() {
             r#"
 fn foo() {
     $0for v in &[0, 1] { }$0
-}"#,
+}
+"#,
             r#"
 fn foo() {
     fun_name();
@@ -1719,7 +1740,8 @@ fn foo() {
 
 fn $0fun_name() {
     for v in &[0, 1] { }
-}"#,
+}
+"#,
         );
     }
 
@@ -1732,7 +1754,8 @@ fn foo() {
     $0loop {
         let m = 1;
     }$0
-}"#,
+}
+"#,
             r#"
 fn foo() {
     fun_name()
@@ -1742,7 +1765,8 @@ fn $0fun_name() -> ! {
     loop {
         let m = 1;
     }
-}"#,
+}
+"#,
         );
     }
 
@@ -1756,7 +1780,8 @@ fn foo() {
         let m = 1;
         break m;
     }$0;
-}"#,
+}
+"#,
             r#"
 fn foo() {
     let v = fun_name();
@@ -1767,7 +1792,8 @@ fn $0fun_name() -> i32 {
         let m = 1;
         break m;
     }
-}"#,
+}
+"#,
         );
     }
 
@@ -1781,7 +1807,8 @@ fn foo() {
         Some(x) => x,
         None => 0,
     }$0;
-}"#,
+}
+"#,
             r#"
 fn foo() {
     let v: i32 = fun_name();
@@ -1792,7 +1819,8 @@ fn $0fun_name() -> i32 {
         Some(x) => x,
         None => 0,
     }
-}"#,
+}
+"#,
         );
     }
 
@@ -1805,7 +1833,8 @@ fn foo() {
     let n = 1;
     let mut v = $0n * n;$0
     v += 1;
-}"#,
+}
+"#,
             r#"
 fn foo() {
     let n = 1;
@@ -1816,7 +1845,8 @@ fn foo() {
 fn $0fun_name(n: i32) -> i32 {
     let mut v = n * n;
     v
-}"#,
+}
+"#,
         );
     }
 
@@ -1832,7 +1862,8 @@ fn foo() {
     let mut w = 3;$0
     v += 1;
     w += 1;
-}"#,
+}
+"#,
             r#"
 fn foo() {
     let m = 2;
@@ -1846,7 +1877,8 @@ fn $0fun_name(m: i32, n: i32) -> (i32, i32) {
     let mut v = m * n;
     let mut w = 3;
     (v, w)
-}"#,
+}
+"#,
         );
     }
 
@@ -1854,12 +1886,13 @@ fn $0fun_name(m: i32, n: i32) -> (i32, i32) {
     fn argument_form_expr() {
         check_assist(
             extract_function,
-            r"
+            r#"
 fn foo() -> u32 {
     let n = 2;
     $0n+2$0
-}",
-            r"
+}
+"#,
+            r#"
 fn foo() -> u32 {
     let n = 2;
     fun_name(n)
@@ -1867,7 +1900,8 @@ fn foo() -> u32 {
 
 fn $0fun_name(n: u32) -> u32 {
     n+2
-}",
+}
+"#,
         )
     }
 
@@ -1875,12 +1909,13 @@ fn $0fun_name(n: u32) -> u32 {
     fn argument_used_twice_form_expr() {
         check_assist(
             extract_function,
-            r"
+            r#"
 fn foo() -> u32 {
     let n = 2;
     $0n+n$0
-}",
-            r"
+}
+"#,
+            r#"
 fn foo() -> u32 {
     let n = 2;
     fun_name(n)
@@ -1888,7 +1923,8 @@ fn foo() -> u32 {
 
 fn $0fun_name(n: u32) -> u32 {
     n+n
-}",
+}
+"#,
         )
     }
 
@@ -1896,13 +1932,14 @@ fn $0fun_name(n: u32) -> u32 {
     fn two_arguments_form_expr() {
         check_assist(
             extract_function,
-            r"
+            r#"
 fn foo() -> u32 {
     let n = 2;
     let m = 3;
     $0n+n*m$0
-}",
-            r"
+}
+"#,
+            r#"
 fn foo() -> u32 {
     let n = 2;
     let m = 3;
@@ -1911,7 +1948,8 @@ fn foo() -> u32 {
 
 fn $0fun_name(n: u32, m: u32) -> u32 {
     n+n*m
-}",
+}
+"#,
         )
     }
 
@@ -1919,13 +1957,14 @@ fn $0fun_name(n: u32, m: u32) -> u32 {
     fn argument_and_locals() {
         check_assist(
             extract_function,
-            r"
+            r#"
 fn foo() -> u32 {
     let n = 2;
     $0let m = 1;
     n + m$0
-}",
-            r"
+}
+"#,
+            r#"
 fn foo() -> u32 {
     let n = 2;
     fun_name(n)
@@ -1934,7 +1973,8 @@ fn foo() -> u32 {
 fn $0fun_name(n: u32) -> u32 {
     let m = 1;
     n + m
-}",
+}
+"#,
         )
     }
 
@@ -1948,18 +1988,20 @@ fn $0fun_name(n: u32) -> u32 {
     fn part_of_expr_stmt() {
         check_assist(
             extract_function,
-            "
+            r#"
 fn foo() {
     $01$0 + 1;
-}",
-            "
+}
+"#,
+            r#"
 fn foo() {
     fun_name() + 1;
 }
 
 fn $0fun_name() -> i32 {
     1
-}",
+}
+"#,
         );
     }
 
@@ -1970,7 +2012,8 @@ fn $0fun_name() -> i32 {
             r#"
 fn foo() {
     $0bar(1 + 1)$0
-}"#,
+}
+"#,
             r#"
 fn foo() {
     fun_name();
@@ -1978,7 +2021,8 @@ fn foo() {
 
 fn $0fun_name() {
     bar(1 + 1)
-}"#,
+}
+"#,
         )
     }
 
@@ -1986,15 +2030,16 @@ fn $0fun_name() {
     fn extract_from_nested() {
         check_assist(
             extract_function,
-            r"
+            r#"
 fn main() {
     let x = true;
     let tuple = match x {
         true => ($02 + 2$0, true)
         _ => (0, false)
     };
-}",
-            r"
+}
+"#,
+            r#"
 fn main() {
     let x = true;
     let tuple = match x {
@@ -2005,7 +2050,8 @@ fn main() {
 
 fn $0fun_name() -> i32 {
     2 + 2
-}",
+}
+"#,
         );
     }
 
@@ -2013,18 +2059,20 @@ fn $0fun_name() -> i32 {
     fn param_from_closure() {
         check_assist(
             extract_function,
-            r"
+            r#"
 fn main() {
     let lambda = |x: u32| $0x * 2$0;
-}",
-            r"
+}
+"#,
+            r#"
 fn main() {
     let lambda = |x: u32| fun_name(x);
 }
 
 fn $0fun_name(x: u32) -> u32 {
     x * 2
-}",
+}
+"#,
         );
     }
 
@@ -2032,18 +2080,20 @@ fn $0fun_name(x: u32) -> u32 {
     fn extract_return_stmt() {
         check_assist(
             extract_function,
-            r"
+            r#"
 fn foo() -> u32 {
     $0return 2 + 2$0;
-}",
-            r"
+}
+"#,
+            r#"
 fn foo() -> u32 {
     return fun_name();
 }
 
 fn $0fun_name() -> u32 {
     2 + 2
-}",
+}
+"#,
         );
     }
 
@@ -2051,13 +2101,14 @@ fn $0fun_name() -> u32 {
     fn does_not_add_extra_whitespace() {
         check_assist(
             extract_function,
-            r"
+            r#"
 fn foo() -> u32 {
 
 
     $0return 2 + 2$0;
-}",
-            r"
+}
+"#,
+            r#"
 fn foo() -> u32 {
 
 
@@ -2066,7 +2117,8 @@ fn foo() -> u32 {
 
 fn $0fun_name() -> u32 {
     2 + 2
-}",
+}
+"#,
         );
     }
 
@@ -2074,13 +2126,14 @@ fn $0fun_name() -> u32 {
     fn break_stmt() {
         check_assist(
             extract_function,
-            r"
+            r#"
 fn main() {
     let result = loop {
         $0break 2 + 2$0;
     };
-}",
-            r"
+}
+"#,
+            r#"
 fn main() {
     let result = loop {
         break fun_name();
@@ -2089,7 +2142,8 @@ fn main() {
 
 fn $0fun_name() -> i32 {
     2 + 2
-}",
+}
+"#,
         );
     }
 
@@ -2097,18 +2151,20 @@ fn $0fun_name() -> i32 {
     fn extract_cast() {
         check_assist(
             extract_function,
-            r"
+            r#"
 fn main() {
     let v = $00f32 as u32$0;
-}",
-            r"
+}
+"#,
+            r#"
 fn main() {
     let v = fun_name();
 }
 
 fn $0fun_name() -> u32 {
     0f32 as u32
-}",
+}
+"#,
         );
     }
 
@@ -2121,15 +2177,16 @@ fn $0fun_name() -> u32 {
     fn method_to_freestanding() {
         check_assist(
             extract_function,
-            r"
+            r#"
 struct S;
 
 impl S {
     fn foo(&self) -> i32 {
         $01+1$0
     }
-}",
-            r"
+}
+"#,
+            r#"
 struct S;
 
 impl S {
@@ -2140,7 +2197,8 @@ impl S {
 
 fn $0fun_name() -> i32 {
     1+1
-}",
+}
+"#,
         );
     }
 
@@ -2148,15 +2206,16 @@ fn $0fun_name() -> i32 {
     fn method_with_reference() {
         check_assist(
             extract_function,
-            r"
+            r#"
 struct S { f: i32 };
 
 impl S {
     fn foo(&self) -> i32 {
         $01+self.f$0
     }
-}",
-            r"
+}
+"#,
+            r#"
 struct S { f: i32 };
 
 impl S {
@@ -2167,7 +2226,8 @@ impl S {
     fn $0fun_name(&self) -> i32 {
         1+self.f
     }
-}",
+}
+"#,
         );
     }
 
@@ -2175,15 +2235,16 @@ impl S {
     fn method_with_mut() {
         check_assist(
             extract_function,
-            r"
+            r#"
 struct S { f: i32 };
 
 impl S {
     fn foo(&mut self) {
         $0self.f += 1;$0
     }
-}",
-            r"
+}
+"#,
+            r#"
 struct S { f: i32 };
 
 impl S {
@@ -2194,7 +2255,8 @@ impl S {
     fn $0fun_name(&mut self) {
         self.f += 1;
     }
-}",
+}
+"#,
         );
     }
 
@@ -2202,13 +2264,14 @@ impl S {
     fn variable_defined_inside_and_used_after_no_ret() {
         check_assist(
             extract_function,
-            r"
+            r#"
 fn foo() {
     let n = 1;
     $0let k = n * n;$0
     let m = k + 1;
-}",
-            r"
+}
+"#,
+            r#"
 fn foo() {
     let n = 1;
     let k = fun_name(n);
@@ -2218,7 +2281,8 @@ fn foo() {
 fn $0fun_name(n: i32) -> i32 {
     let k = n * n;
     k
-}",
+}
+"#,
         );
     }
 
@@ -2226,13 +2290,14 @@ fn $0fun_name(n: i32) -> i32 {
     fn variable_defined_inside_and_used_after_mutably_no_ret() {
         check_assist(
             extract_function,
-            r"
+            r#"
 fn foo() {
     let n = 1;
     $0let mut k = n * n;$0
     k += 1;
-}",
-            r"
+}
+"#,
+            r#"
 fn foo() {
     let n = 1;
     let mut k = fun_name(n);
@@ -2242,7 +2307,8 @@ fn foo() {
 fn $0fun_name(n: i32) -> i32 {
     let mut k = n * n;
     k
-}",
+}
+"#,
         );
     }
 
@@ -2250,14 +2316,15 @@ fn $0fun_name(n: i32) -> i32 {
     fn two_variables_defined_inside_and_used_after_no_ret() {
         check_assist(
             extract_function,
-            r"
+            r#"
 fn foo() {
     let n = 1;
     $0let k = n * n;
     let m = k + 2;$0
     let h = k + m;
-}",
-            r"
+}
+"#,
+            r#"
 fn foo() {
     let n = 1;
     let (k, m) = fun_name(n);
@@ -2268,7 +2335,8 @@ fn $0fun_name(n: i32) -> (i32, i32) {
     let k = n * n;
     let m = k + 2;
     (k, m)
-}",
+}
+"#,
         );
     }
 
@@ -2276,7 +2344,7 @@ fn $0fun_name(n: i32) -> (i32, i32) {
     fn multi_variables_defined_inside_and_used_after_mutably_no_ret() {
         check_assist(
             extract_function,
-            r"
+            r#"
 fn foo() {
     let n = 1;
     $0let mut k = n * n;
@@ -2285,8 +2353,9 @@ fn foo() {
     o += 1;$0
     k += o;
     m = 1;
-}",
-            r"
+}
+"#,
+            r#"
 fn foo() {
     let n = 1;
     let (mut k, mut m, o) = fun_name(n);
@@ -2300,7 +2369,8 @@ fn $0fun_name(n: i32) -> (i32, i32, i32) {
     let mut o = m + 3;
     o += 1;
     (k, m, o)
-}",
+}
+"#,
         );
     }
 
@@ -2308,13 +2378,14 @@ fn $0fun_name(n: i32) -> (i32, i32, i32) {
     fn nontrivial_patterns_define_variables() {
         check_assist(
             extract_function,
-            r"
+            r#"
 struct Counter(i32);
 fn foo() {
     $0let Counter(n) = Counter(0);$0
     let m = n;
-}",
-            r"
+}
+"#,
+            r#"
 struct Counter(i32);
 fn foo() {
     let n = fun_name();
@@ -2324,7 +2395,8 @@ fn foo() {
 fn $0fun_name() -> i32 {
     let Counter(n) = Counter(0);
     n
-}",
+}
+"#,
         );
     }
 
@@ -2332,13 +2404,14 @@ fn $0fun_name() -> i32 {
     fn struct_with_two_fields_pattern_define_variables() {
         check_assist(
             extract_function,
-            r"
+            r#"
 struct Counter { n: i32, m: i32 };
 fn foo() {
     $0let Counter { n, m: k } = Counter { n: 1, m: 2 };$0
     let h = n + k;
-}",
-            r"
+}
+"#,
+            r#"
 struct Counter { n: i32, m: i32 };
 fn foo() {
     let (n, k) = fun_name();
@@ -2348,7 +2421,8 @@ fn foo() {
 fn $0fun_name() -> (i32, i32) {
     let Counter { n, m: k } = Counter { n: 1, m: 2 };
     (n, k)
-}",
+}
+"#,
         );
     }
 
@@ -2356,13 +2430,14 @@ fn $0fun_name() -> (i32, i32) {
     fn mut_var_from_outer_scope() {
         check_assist(
             extract_function,
-            r"
+            r#"
 fn foo() {
     let mut n = 1;
     $0n += 1;$0
     let m = n + 1;
-}",
-            r"
+}
+"#,
+            r#"
 fn foo() {
     let mut n = 1;
     fun_name(&mut n);
@@ -2371,7 +2446,8 @@ fn foo() {
 
 fn $0fun_name(n: &mut i32) {
     *n += 1;
-}",
+}
+"#,
         );
     }
 
@@ -2379,14 +2455,15 @@ fn $0fun_name(n: &mut i32) {
     fn mut_field_from_outer_scope() {
         check_assist(
             extract_function,
-            r"
+            r#"
 struct C { n: i32 }
 fn foo() {
     let mut c = C { n: 0 };
     $0c.n += 1;$0
     let m = c.n + 1;
-}",
-            r"
+}
+"#,
+            r#"
 struct C { n: i32 }
 fn foo() {
     let mut c = C { n: 0 };
@@ -2396,7 +2473,8 @@ fn foo() {
 
 fn $0fun_name(c: &mut C) {
     c.n += 1;
-}",
+}
+"#,
         );
     }
 
@@ -2404,7 +2482,7 @@ fn $0fun_name(c: &mut C) {
     fn mut_nested_field_from_outer_scope() {
         check_assist(
             extract_function,
-            r"
+            r#"
 struct P { n: i32}
 struct C { p: P }
 fn foo() {
@@ -2414,8 +2492,9 @@ fn foo() {
     $0c.p.n += u.p.n;
     let r = &mut v.p.n;$0
     let m = c.p.n + v.p.n + u.p.n;
-}",
-            r"
+}
+"#,
+            r#"
 struct P { n: i32}
 struct C { p: P }
 fn foo() {
@@ -2429,7 +2508,8 @@ fn foo() {
 fn $0fun_name(c: &mut C, u: &C, v: &mut C) {
     c.p.n += u.p.n;
     let r = &mut v.p.n;
-}",
+}
+"#,
         );
     }
 
@@ -2437,7 +2517,7 @@ fn $0fun_name(c: &mut C, u: &C, v: &mut C) {
     fn mut_param_many_usages_stmt() {
         check_assist(
             extract_function,
-            r"
+            r#"
 fn bar(k: i32) {}
 trait I: Copy {
     fn succ(&self) -> Self;
@@ -2458,8 +2538,9 @@ fn foo() {
     *v = v.succ();
     n.succ();$0
     let m = n + 1;
-}",
-            r"
+}
+"#,
+            r#"
 fn bar(k: i32) {}
 trait I: Copy {
     fn succ(&self) -> Self;
@@ -2484,7 +2565,8 @@ fn $0fun_name(n: &mut i32) {
     let v = n;
     *v = v.succ();
     n.succ();
-}",
+}
+"#,
         );
     }
 
@@ -2492,7 +2574,7 @@ fn $0fun_name(n: &mut i32) {
     fn mut_param_many_usages_expr() {
         check_assist(
             extract_function,
-            r"
+            r#"
 fn bar(k: i32) {}
 trait I: Copy {
     fn succ(&self) -> Self;
@@ -2515,8 +2597,9 @@ fn foo() {
         n.succ();
     }$0
     let m = n + 1;
-}",
-            r"
+}
+"#,
+            r#"
 fn bar(k: i32) {}
 trait I: Copy {
     fn succ(&self) -> Self;
@@ -2541,7 +2624,8 @@ fn $0fun_name(n: &mut i32) {
     let v = n;
     *v = v.succ();
     n.succ();
-}",
+}
+"#,
         );
     }
 
@@ -2549,11 +2633,12 @@ fn $0fun_name(n: &mut i32) {
     fn mut_param_by_value() {
         check_assist(
             extract_function,
-            r"
+            r#"
 fn foo() {
     let mut n = 1;
     $0n += 1;$0
-}",
+}
+"#,
             r"
 fn foo() {
     let mut n = 1;
@@ -2562,7 +2647,8 @@ fn foo() {
 
 fn $0fun_name(mut n: i32) {
     n += 1;
-}",
+}
+",
         );
     }
 
@@ -2570,14 +2656,15 @@ fn $0fun_name(mut n: i32) {
     fn mut_param_because_of_mut_ref() {
         check_assist(
             extract_function,
-            r"
+            r#"
 fn foo() {
     let mut n = 1;
     $0let v = &mut n;
     *v += 1;$0
     let k = n;
-}",
-            r"
+}
+"#,
+            r#"
 fn foo() {
     let mut n = 1;
     fun_name(&mut n);
@@ -2587,7 +2674,8 @@ fn foo() {
 fn $0fun_name(n: &mut i32) {
     let v = n;
     *v += 1;
-}",
+}
+"#,
         );
     }
 
@@ -2600,8 +2688,9 @@ fn foo() {
     let mut n = 1;
     $0let v = &mut n;
     *v += 1;$0
-}",
-            r"
+}
+",
+            r#"
 fn foo() {
     let mut n = 1;
     fun_name(n);
@@ -2610,7 +2699,8 @@ fn foo() {
 fn $0fun_name(mut n: i32) {
     let v = &mut n;
     *v += 1;
-}",
+}
+"#,
         );
     }
 
@@ -2618,7 +2708,7 @@ fn $0fun_name(mut n: i32) {
     fn mut_method_call() {
         check_assist(
             extract_function,
-            r"
+            r#"
 trait I {
     fn inc(&mut self);
 }
@@ -2628,8 +2718,9 @@ impl I for i32 {
 fn foo() {
     let mut n = 1;
     $0n.inc();$0
-}",
-            r"
+}
+"#,
+            r#"
 trait I {
     fn inc(&mut self);
 }
@@ -2643,7 +2734,8 @@ fn foo() {
 
 fn $0fun_name(mut n: i32) {
     n.inc();
-}",
+}
+"#,
         );
     }
 
@@ -2651,7 +2743,7 @@ fn $0fun_name(mut n: i32) {
     fn shared_method_call() {
         check_assist(
             extract_function,
-            r"
+            r#"
 trait I {
     fn succ(&self);
 }
@@ -2661,7 +2753,8 @@ impl I for i32 {
 fn foo() {
     let mut n = 1;
     $0n.succ();$0
-}",
+}
+"#,
             r"
 trait I {
     fn succ(&self);
@@ -2676,7 +2769,8 @@ fn foo() {
 
 fn $0fun_name(n: i32) {
     n.succ();
-}",
+}
+",
         );
     }
 
@@ -2684,7 +2778,7 @@ fn $0fun_name(n: i32) {
     fn mut_method_call_with_other_receiver() {
         check_assist(
             extract_function,
-            r"
+            r#"
 trait I {
     fn inc(&mut self, n: i32);
 }
@@ -2695,7 +2789,8 @@ fn foo() {
     let mut n = 1;
     $0let mut m = 2;
     m.inc(n);$0
-}",
+}
+"#,
             r"
 trait I {
     fn inc(&mut self, n: i32);
@@ -2711,7 +2806,8 @@ fn foo() {
 fn $0fun_name(n: i32) {
     let mut m = 2;
     m.inc(n);
-}",
+}
+",
         );
     }
 
@@ -2719,12 +2815,13 @@ fn $0fun_name(n: i32) {
     fn non_copy_without_usages_after() {
         check_assist(
             extract_function,
-            r"
+            r#"
 struct Counter(i32);
 fn foo() {
     let c = Counter(0);
     $0let n = c.0;$0
-}",
+}
+"#,
             r"
 struct Counter(i32);
 fn foo() {
@@ -2734,7 +2831,8 @@ fn foo() {
 
 fn $0fun_name(c: Counter) {
     let n = c.0;
-}",
+}
+",
         );
     }
 
@@ -2748,8 +2846,9 @@ fn foo() {
     let c = Counter(0);
     $0let n = c.0;$0
     let m = c.0;
-}",
-            r"
+}
+",
+            r#"
 struct Counter(i32);
 fn foo() {
     let c = Counter(0);
@@ -2759,7 +2858,8 @@ fn foo() {
 
 fn $0fun_name(c: &Counter) {
     let n = c.0;
-}",
+}
+"#,
         );
     }
 
@@ -2767,19 +2867,15 @@ fn $0fun_name(c: &Counter) {
     fn copy_used_after() {
         check_assist(
             extract_function,
-            r##"
-#[lang = "copy"]
-pub trait Copy {}
-impl Copy for i32 {}
+            r#"
+//- minicore: copy
 fn foo() {
     let n = 0;
     $0let m = n;$0
     let k = n;
-}"##,
-            r##"
-#[lang = "copy"]
-pub trait Copy {}
-impl Copy for i32 {}
+}
+"#,
+            r#"
 fn foo() {
     let n = 0;
     fun_name(n);
@@ -2788,7 +2884,8 @@ fn foo() {
 
 fn $0fun_name(n: i32) {
     let m = n;
-}"##,
+}
+"#,
         )
     }
 
@@ -2796,21 +2893,19 @@ fn $0fun_name(n: i32) {
     fn copy_custom_used_after() {
         check_assist(
             extract_function,
-            r##"
-#[lang = "copy"]
-pub trait Copy {}
+            r#"
+//- minicore: copy, derive
+#[derive(Clone, Copy)]
 struct Counter(i32);
-impl Copy for Counter {}
 fn foo() {
     let c = Counter(0);
     $0let n = c.0;$0
     let m = c.0;
-}"##,
-            r##"
-#[lang = "copy"]
-pub trait Copy {}
+}
+"#,
+            r#"
+#[derive(Clone, Copy)]
 struct Counter(i32);
-impl Copy for Counter {}
 fn foo() {
     let c = Counter(0);
     fun_name(c);
@@ -2819,7 +2914,8 @@ fn foo() {
 
 fn $0fun_name(c: Counter) {
     let n = c.0;
-}"##,
+}
+"#,
         );
     }
 
@@ -2827,7 +2923,7 @@ fn $0fun_name(c: Counter) {
     fn indented_stmts() {
         check_assist(
             extract_function,
-            r"
+            r#"
 fn foo() {
     if true {
         loop {
@@ -2835,8 +2931,9 @@ fn foo() {
             let m = 2;$0
         }
     }
-}",
-            r"
+}
+"#,
+            r#"
 fn foo() {
     if true {
         loop {
@@ -2848,7 +2945,8 @@ fn foo() {
 fn $0fun_name() {
     let n = 1;
     let m = 2;
-}",
+}
+"#,
         );
     }
 
@@ -2856,7 +2954,7 @@ fn $0fun_name() {
     fn indented_stmts_inside_mod() {
         check_assist(
             extract_function,
-            r"
+            r#"
 mod bar {
     fn foo() {
         if true {
@@ -2866,8 +2964,9 @@ mod bar {
             }
         }
     }
-}",
-            r"
+}
+"#,
+            r#"
 mod bar {
     fn foo() {
         if true {
@@ -2881,7 +2980,8 @@ mod bar {
         let n = 1;
         let m = 2;
     }
-}",
+}
+"#,
         );
     }
 
@@ -2889,12 +2989,8 @@ mod bar {
     fn break_loop() {
         check_assist(
             extract_function,
-            r##"
-enum Option<T> {
-    #[lang = "None"] None,
-    #[lang = "Some"] Some(T),
-}
-use Option::*;
+            r#"
+//- minicore: option
 fn foo() {
     loop {
         let n = 1;
@@ -2903,13 +2999,9 @@ fn foo() {
         let k = 2;$0
         let h = 1 + k;
     }
-}"##,
-            r##"
-enum Option<T> {
-    #[lang = "None"] None,
-    #[lang = "Some"] Some(T),
 }
-use Option::*;
+"#,
+            r#"
 fn foo() {
     loop {
         let n = 1;
@@ -2926,7 +3018,8 @@ fn $0fun_name(n: i32) -> Option<i32> {
     return None;
     let k = 2;
     Some(k)
-}"##,
+}
+"#,
         );
     }
 
@@ -2934,31 +3027,17 @@ fn $0fun_name(n: i32) -> Option<i32> {
     fn return_to_parent() {
         check_assist(
             extract_function,
-            r##"
-#[lang = "copy"]
-pub trait Copy {}
-impl Copy for i32 {}
-enum Result<T, E> {
-    #[lang = "Ok"] Ok(T),
-    #[lang = "Err"] Err(E),
-}
-use Result::*;
+            r#"
+//- minicore: copy, result
 fn foo() -> i64 {
     let n = 1;
     $0let m = n + 1;
     return 1;
     let k = 2;$0
     (n + k) as i64
-}"##,
-            r##"
-#[lang = "copy"]
-pub trait Copy {}
-impl Copy for i32 {}
-enum Result<T, E> {
-    #[lang = "Ok"] Ok(T),
-    #[lang = "Err"] Err(E),
-}
-use Result::*;
+}
+"#,
+            r#"
 fn foo() -> i64 {
     let n = 1;
     let k = match fun_name(n) {
@@ -2973,7 +3052,8 @@ fn $0fun_name(n: i32) -> Result<i32, i64> {
     return Err(1);
     let k = 2;
     Ok(k)
-}"##,
+}
+"#,
         );
     }
 
@@ -2982,7 +3062,7 @@ fn $0fun_name(n: i32) -> Result<i32, i64> {
         cov_mark::check!(external_control_flow_break_and_continue);
         check_assist_not_applicable(
             extract_function,
-            r##"
+            r#"
 fn foo() {
     loop {
         let n = 1;
@@ -2993,7 +3073,8 @@ fn foo() {
         let k = k + 1;$0
         let r = n + k;
     }
-}"##,
+}
+"#,
         );
     }
 
@@ -3002,7 +3083,7 @@ fn foo() {
         cov_mark::check!(external_control_flow_return_and_bc);
         check_assist_not_applicable(
             extract_function,
-            r##"
+            r#"
 fn foo() {
     loop {
         let n = 1;
@@ -3013,7 +3094,8 @@ fn foo() {
         let k = k + 1;$0
         let r = n + k;
     }
-}"##,
+}
+"#,
         );
     }
 
@@ -3021,7 +3103,7 @@ fn foo() {
     fn break_loop_with_if() {
         check_assist(
             extract_function,
-            r##"
+            r#"
 fn foo() {
     loop {
         let mut n = 1;
@@ -3030,8 +3112,9 @@ fn foo() {
         n += m;$0
         let h = 1 + n;
     }
-}"##,
-            r##"
+}
+"#,
+            r#"
 fn foo() {
     loop {
         let mut n = 1;
@@ -3047,7 +3130,8 @@ fn $0fun_name(n: &mut i32) -> bool {
     return true;
     *n += m;
     false
-}"##,
+}
+"#,
         );
     }
 
@@ -3055,7 +3139,7 @@ fn $0fun_name(n: &mut i32) -> bool {
     fn break_loop_nested() {
         check_assist(
             extract_function,
-            r##"
+            r#"
 fn foo() {
     loop {
         let mut n = 1;
@@ -3065,8 +3149,9 @@ fn foo() {
         }$0
         let h = 1;
     }
-}"##,
-            r##"
+}
+"#,
+            r#"
 fn foo() {
     loop {
         let mut n = 1;
@@ -3083,7 +3168,8 @@ fn $0fun_name(n: i32) -> bool {
         return true;
     }
     false
-}"##,
+}
+"#,
         );
     }
 
@@ -3091,7 +3177,7 @@ fn $0fun_name(n: i32) -> bool {
     fn return_from_nested_loop() {
         check_assist(
             extract_function,
-            r##"
+            r#"
 fn foo() {
     loop {
         let n = 1;
@@ -3103,8 +3189,9 @@ fn foo() {
         let m = k + 1;$0
         let h = 1 + m;
     }
-}"##,
-            r##"
+}
+"#,
+            r#"
 fn foo() {
     loop {
         let n = 1;
@@ -3123,7 +3210,8 @@ fn $0fun_name() -> Option<i32> {
     }
     let m = k + 1;
     Some(m)
-}"##,
+}
+"#,
         );
     }
 
@@ -3131,7 +3219,7 @@ fn $0fun_name() -> Option<i32> {
     fn break_from_nested_loop() {
         check_assist(
             extract_function,
-            r##"
+            r#"
 fn foo() {
     loop {
         let n = 1;
@@ -3142,8 +3230,9 @@ fn foo() {
         let m = k + 1;$0
         let h = 1 + m;
     }
-}"##,
-            r##"
+}
+"#,
+            r#"
 fn foo() {
     loop {
         let n = 1;
@@ -3159,7 +3248,8 @@ fn $0fun_name() -> i32 {
     }
     let m = k + 1;
     m
-}"##,
+}
+"#,
         );
     }
 
@@ -3167,7 +3257,7 @@ fn $0fun_name() -> i32 {
     fn break_from_nested_and_outer_loops() {
         check_assist(
             extract_function,
-            r##"
+            r#"
 fn foo() {
     loop {
         let n = 1;
@@ -3181,8 +3271,9 @@ fn foo() {
         let m = k + 1;$0
         let h = 1 + m;
     }
-}"##,
-            r##"
+}
+"#,
+            r#"
 fn foo() {
     loop {
         let n = 1;
@@ -3204,7 +3295,8 @@ fn $0fun_name() -> Option<i32> {
     }
     let m = k + 1;
     Some(m)
-}"##,
+}
+"#,
         );
     }
 
@@ -3212,7 +3304,7 @@ fn $0fun_name() -> Option<i32> {
     fn return_from_nested_fn() {
         check_assist(
             extract_function,
-            r##"
+            r#"
 fn foo() {
     loop {
         let n = 1;
@@ -3223,8 +3315,9 @@ fn foo() {
         let m = k + 1;$0
         let h = 1 + m;
     }
-}"##,
-            r##"
+}
+"#,
+            r#"
 fn foo() {
     loop {
         let n = 1;
@@ -3240,7 +3333,8 @@ fn $0fun_name() -> i32 {
     }
     let m = k + 1;
     m
-}"##,
+}
+"#,
         );
     }
 
@@ -3248,7 +3342,7 @@ fn $0fun_name() -> i32 {
     fn break_with_value() {
         check_assist(
             extract_function,
-            r##"
+            r#"
 fn foo() -> i32 {
     loop {
         let n = 1;
@@ -3259,8 +3353,9 @@ fn foo() -> i32 {
         let m = k + 1;$0
         let h = 1;
     }
-}"##,
-            r##"
+}
+"#,
+            r#"
 fn foo() -> i32 {
     loop {
         let n = 1;
@@ -3278,7 +3373,8 @@ fn $0fun_name() -> Option<i32> {
     }
     let m = k + 1;
     None
-}"##,
+}
+"#,
         );
     }
 
@@ -3286,7 +3382,7 @@ fn $0fun_name() -> Option<i32> {
     fn break_with_value_and_return() {
         check_assist(
             extract_function,
-            r##"
+            r#"
 fn foo() -> i64 {
     loop {
         let n = 1;
@@ -3298,8 +3394,9 @@ fn foo() -> i64 {
         let m = k + 1;$0
         let h = 1 + m;
     }
-}"##,
-            r##"
+}
+"#,
+            r#"
 fn foo() -> i64 {
     loop {
         let n = 1;
@@ -3318,7 +3415,8 @@ fn $0fun_name() -> Result<i32, i64> {
     }
     let m = k + 1;
     Ok(m)
-}"##,
+}
+"#,
         );
     }
 
@@ -3326,9 +3424,8 @@ fn $0fun_name() -> Result<i32, i64> {
     fn try_option() {
         check_assist(
             extract_function,
-            r##"
-enum Option<T> { None, Some(T), }
-use Option::*;
+            r#"
+//- minicore: option
 fn bar() -> Option<i32> { None }
 fn foo() -> Option<()> {
     let n = bar()?;
@@ -3336,10 +3433,9 @@ fn foo() -> Option<()> {
     let m = k + 1;$0
     let h = 1 + m;
     Some(())
-}"##,
-            r##"
-enum Option<T> { None, Some(T), }
-use Option::*;
+}
+"#,
+            r#"
 fn bar() -> Option<i32> { None }
 fn foo() -> Option<()> {
     let n = bar()?;
@@ -3352,7 +3448,8 @@ fn $0fun_name() -> Option<i32> {
     let k = foo()?;
     let m = k + 1;
     Some(m)
-}"##,
+}
+"#,
         );
     }
 
@@ -3360,19 +3457,17 @@ fn $0fun_name() -> Option<i32> {
     fn try_option_unit() {
         check_assist(
             extract_function,
-            r##"
-enum Option<T> { None, Some(T), }
-use Option::*;
+            r#"
+//- minicore: option
 fn foo() -> Option<()> {
     let n = 1;
     $0let k = foo()?;
     let m = k + 1;$0
     let h = 1 + n;
     Some(())
-}"##,
-            r##"
-enum Option<T> { None, Some(T), }
-use Option::*;
+}
+"#,
+            r#"
 fn foo() -> Option<()> {
     let n = 1;
     fun_name()?;
@@ -3384,7 +3479,8 @@ fn $0fun_name() -> Option<()> {
     let k = foo()?;
     let m = k + 1;
     Some(())
-}"##,
+}
+"#,
         );
     }
 
@@ -3392,19 +3488,17 @@ fn $0fun_name() -> Option<()> {
     fn try_result() {
         check_assist(
             extract_function,
-            r##"
-enum Result<T, E> { Ok(T), Err(E), }
-use Result::*;
+            r#"
+//- minicore: result
 fn foo() -> Result<(), i64> {
     let n = 1;
     $0let k = foo()?;
     let m = k + 1;$0
     let h = 1 + m;
     Ok(())
-}"##,
-            r##"
-enum Result<T, E> { Ok(T), Err(E), }
-use Result::*;
+}
+"#,
+            r#"
 fn foo() -> Result<(), i64> {
     let n = 1;
     let m = fun_name()?;
@@ -3416,7 +3510,8 @@ fn $0fun_name() -> Result<i32, i64> {
     let k = foo()?;
     let m = k + 1;
     Ok(m)
-}"##,
+}
+"#,
         );
     }
 
@@ -3424,9 +3519,8 @@ fn $0fun_name() -> Result<i32, i64> {
     fn try_option_with_return() {
         check_assist(
             extract_function,
-            r##"
-enum Option<T> { None, Some(T) }
-use Option::*;
+            r#"
+//- minicore: option
 fn foo() -> Option<()> {
     let n = 1;
     $0let k = foo()?;
@@ -3436,10 +3530,9 @@ fn foo() -> Option<()> {
     let m = k + 1;$0
     let h = 1 + m;
     Some(())
-}"##,
-            r##"
-enum Option<T> { None, Some(T) }
-use Option::*;
+}
+"#,
+            r#"
 fn foo() -> Option<()> {
     let n = 1;
     let m = fun_name()?;
@@ -3454,7 +3547,8 @@ fn $0fun_name() -> Option<i32> {
     }
     let m = k + 1;
     Some(m)
-}"##,
+}
+"#,
         );
     }
 
@@ -3462,9 +3556,8 @@ fn $0fun_name() -> Option<i32> {
     fn try_result_with_return() {
         check_assist(
             extract_function,
-            r##"
-enum Result<T, E> { Ok(T), Err(E), }
-use Result::*;
+            r#"
+//- minicore: result
 fn foo() -> Result<(), i64> {
     let n = 1;
     $0let k = foo()?;
@@ -3474,10 +3567,9 @@ fn foo() -> Result<(), i64> {
     let m = k + 1;$0
     let h = 1 + m;
     Ok(())
-}"##,
-            r##"
-enum Result<T, E> { Ok(T), Err(E), }
-use Result::*;
+}
+"#,
+            r#"
 fn foo() -> Result<(), i64> {
     let n = 1;
     let m = fun_name()?;
@@ -3492,7 +3584,8 @@ fn $0fun_name() -> Result<i32, i64> {
     }
     let m = k + 1;
     Ok(m)
-}"##,
+}
+"#,
         );
     }
 
@@ -3501,9 +3594,8 @@ fn $0fun_name() -> Result<i32, i64> {
         cov_mark::check!(external_control_flow_try_and_bc);
         check_assist_not_applicable(
             extract_function,
-            r##"
-enum Option<T> { None, Some(T) }
-use Option::*;
+            r#"
+//- minicore: option
 fn foo() -> Option<()> {
     loop {
         let n = Some(1);
@@ -3514,7 +3606,8 @@ fn foo() -> Option<()> {
         let r = n + k;
     }
     Some(())
-}"##,
+}
+"#,
         );
     }
 
@@ -3523,9 +3616,8 @@ fn foo() -> Option<()> {
         cov_mark::check!(external_control_flow_try_and_return_non_err);
         check_assist_not_applicable(
             extract_function,
-            r##"
-enum Result<T, E> { Ok(T), Err(E), }
-use Result::*;
+            r#"
+//- minicore: result
 fn foo() -> Result<(), i64> {
     let n = 1;
     $0let k = foo()?;
@@ -3535,7 +3627,8 @@ fn foo() -> Result<(), i64> {
     let m = k + 1;$0
     let h = 1 + m;
     Ok(())
-}"##,
+}
+"#,
         );
     }
 
@@ -3543,7 +3636,7 @@ fn foo() -> Result<(), i64> {
     fn param_usage_in_macro() {
         check_assist(
             extract_function,
-            r"
+            r#"
 macro_rules! m {
     ($val:expr) => { $val };
 }
@@ -3552,8 +3645,9 @@ fn foo() {
     let n = 1;
     $0let k = n * m!(n);$0
     let m = k + 1;
-}",
-            r"
+}
+"#,
+            r#"
 macro_rules! m {
     ($val:expr) => { $val };
 }
@@ -3567,7 +3661,8 @@ fn foo() {
 fn $0fun_name(n: i32) -> i32 {
     let k = n * m!(n);
     k
-}",
+}
+"#,
         );
     }
 
@@ -3575,7 +3670,8 @@ fn $0fun_name(n: i32) -> i32 {
     fn extract_with_await() {
         check_assist(
             extract_function,
-            r#"fn main() {
+            r#"
+fn main() {
     $0some_function().await;$0
 }
 
@@ -3603,7 +3699,8 @@ async fn some_function() {
     fn extract_with_await_in_args() {
         check_assist(
             extract_function,
-            r#"fn main() {
+            r#"
+fn main() {
     $0function_call("a", some_function().await);$0
 }
 
diff --git a/crates/ide_assists/src/handlers/extract_struct_from_enum_variant.rs b/crates/ide_assists/src/handlers/extract_struct_from_enum_variant.rs
index da6df9106..430710448 100644
--- a/crates/ide_assists/src/handlers/extract_struct_from_enum_variant.rs
+++ b/crates/ide_assists/src/handlers/extract_struct_from_enum_variant.rs
@@ -48,6 +48,7 @@ pub(crate) fn extract_struct_from_enum_variant(
     let variant_name = variant.name()?;
     let variant_hir = ctx.sema.to_def(&variant)?;
     if existing_definition(ctx.db(), &variant_name, &variant_hir) {
+        cov_mark::hit!(test_extract_enum_not_applicable_if_struct_exists);
         return None;
     }
 
@@ -300,18 +301,10 @@ fn reference_to_node(
 
 #[cfg(test)]
 mod tests {
-    use ide_db::helpers::FamousDefs;
-
     use crate::tests::{check_assist, check_assist_not_applicable};
 
     use super::*;
 
-    fn check_not_applicable(ra_fixture: &str) {
-        let fixture =
-            format!("//- /main.rs crate:main deps:core\n{}\n{}", ra_fixture, FamousDefs::FIXTURE);
-        check_assist_not_applicable(extract_struct_from_enum_variant, &fixture)
-    }
-
     #[test]
     fn test_extract_struct_several_fields_tuple() {
         check_assist(
@@ -699,29 +692,33 @@ fn foo() {
 
     #[test]
     fn test_extract_enum_not_applicable_for_element_with_no_fields() {
-        check_not_applicable("enum A { $0One }");
+        check_assist_not_applicable(extract_struct_from_enum_variant, r#"enum A { $0One }"#);
     }
 
     #[test]
     fn test_extract_enum_not_applicable_if_struct_exists() {
-        check_not_applicable(
-            r#"struct One;
-        enum A { $0One(u8, u32) }"#,
+        cov_mark::check!(test_extract_enum_not_applicable_if_struct_exists);
+        check_assist_not_applicable(
+            extract_struct_from_enum_variant,
+            r#"
+struct One;
+enum A { $0One(u8, u32) }
+"#,
         );
     }
 
     #[test]
     fn test_extract_not_applicable_one_field() {
-        check_not_applicable(r"enum A { $0One(u32) }");
+        check_assist_not_applicable(extract_struct_from_enum_variant, r"enum A { $0One(u32) }");
     }
 
     #[test]
     fn test_extract_not_applicable_no_field_tuple() {
-        check_not_applicable(r"enum A { $0None() }");
+        check_assist_not_applicable(extract_struct_from_enum_variant, r"enum A { $0None() }");
     }
 
     #[test]
     fn test_extract_not_applicable_no_field_named() {
-        check_not_applicable(r"enum A { $0None {} }");
+        check_assist_not_applicable(extract_struct_from_enum_variant, r"enum A { $0None {} }");
     }
 }
diff --git a/crates/ide_assists/src/handlers/fill_match_arms.rs b/crates/ide_assists/src/handlers/fill_match_arms.rs
index cd0f6dba9..318faa0fc 100644
--- a/crates/ide_assists/src/handlers/fill_match_arms.rs
+++ b/crates/ide_assists/src/handlers/fill_match_arms.rs
@@ -481,26 +481,21 @@ fn main() {
         check_assist(
             fill_match_arms,
             r#"
-enum Option<T> { Some(T), None }
-use Option::*;
-
+//- minicore: option
 fn main() {
     match None$0 {
         None => {}
     }
 }
-            "#,
+"#,
             r#"
-enum Option<T> { Some(T), None }
-use Option::*;
-
 fn main() {
     match None {
         None => {}
         Some(${0:_}) => todo!(),
     }
 }
-            "#,
+"#,
         );
     }
 
diff --git a/crates/ide_assists/src/handlers/remove_dbg.rs b/crates/ide_assists/src/handlers/remove_dbg.rs
index b20fe992d..5866d8974 100644
--- a/crates/ide_assists/src/handlers/remove_dbg.rs
+++ b/crates/ide_assists/src/handlers/remove_dbg.rs
@@ -35,14 +35,14 @@ pub(crate) fn remove_dbg(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
                             .prev_sibling_or_token()
                             .and_then(whitespace_start)
                             .map(|start| TextRange::new(start, macro_call.syntax().text_range().end()))
-                            .unwrap_or(macro_call.syntax().text_range())
+                            .unwrap_or_else(|| macro_call.syntax().text_range())
                     },
                     ast::ExprStmt(it) => {
                         let start = it
                             .syntax()
                             .prev_sibling_or_token()
                             .and_then(whitespace_start)
-                            .unwrap_or(it.syntax().text_range().start());
+                            .unwrap_or_else(|| it.syntax().text_range().start());
                         let end = it.syntax().text_range().end();
 
                         TextRange::new(start, end)
diff --git a/crates/ide_assists/src/handlers/replace_if_let_with_match.rs b/crates/ide_assists/src/handlers/replace_if_let_with_match.rs
index 9404aa26d..f37aa0d53 100644
--- a/crates/ide_assists/src/handlers/replace_if_let_with_match.rs
+++ b/crates/ide_assists/src/handlers/replace_if_let_with_match.rs
@@ -262,9 +262,7 @@ impl VariantData {
         check_assist(
             replace_if_let_with_match,
             r#"
-enum Option<T> { Some(T), None }
-use Option::*;
-
+//- minicore: option
 fn foo(x: Option<i32>) {
     $0if let Some(x) = x {
         println!("{}", x)
@@ -272,18 +270,15 @@ fn foo(x: Option<i32>) {
         println!("none")
     }
 }
-           "#,
+"#,
             r#"
-enum Option<T> { Some(T), None }
-use Option::*;
-
 fn foo(x: Option<i32>) {
     match x {
         Some(x) => println!("{}", x),
         None => println!("none"),
     }
 }
-           "#,
+"#,
         );
     }
 
@@ -292,9 +287,7 @@ fn foo(x: Option<i32>) {
         check_assist(
             replace_if_let_with_match,
             r#"
-enum Option<T> { Some(T), None }
-use Option::*;
-
+//- minicore: option
 fn foo(x: Option<i32>) {
     $0if let None = x {
         println!("none")
@@ -302,18 +295,15 @@ fn foo(x: Option<i32>) {
         println!("some")
     }
 }
-           "#,
+"#,
             r#"
-enum Option<T> { Some(T), None }
-use Option::*;
-
 fn foo(x: Option<i32>) {
     match x {
         None => println!("none"),
         Some(_) => println!("some"),
     }
 }
-           "#,
+"#,
         );
     }
 
@@ -322,9 +312,7 @@ fn foo(x: Option<i32>) {
         check_assist(
             replace_if_let_with_match,
             r#"
-enum Result<T, E> { Ok(T), Err(E) }
-use Result::*;
-
+//- minicore: result
 fn foo(x: Result<i32, ()>) {
     $0if let Ok(x) = x {
         println!("{}", x)
@@ -332,18 +320,15 @@ fn foo(x: Result<i32, ()>) {
         println!("none")
     }
 }
-           "#,
+"#,
             r#"
-enum Result<T, E> { Ok(T), Err(E) }
-use Result::*;
-
 fn foo(x: Result<i32, ()>) {
     match x {
         Ok(x) => println!("{}", x),
         Err(_) => println!("none"),
     }
 }
-           "#,
+"#,
         );
     }
 
@@ -352,9 +337,7 @@ fn foo(x: Result<i32, ()>) {
         check_assist(
             replace_if_let_with_match,
             r#"
-enum Result<T, E> { Ok(T), Err(E) }
-use Result::*;
-
+//- minicore: result
 fn foo(x: Result<i32, ()>) {
     $0if let Err(x) = x {
         println!("{}", x)
@@ -362,18 +345,15 @@ fn foo(x: Result<i32, ()>) {
         println!("ok")
     }
 }
-           "#,
+"#,
             r#"
-enum Result<T, E> { Ok(T), Err(E) }
-use Result::*;
-
 fn foo(x: Result<i32, ()>) {
     match x {
         Err(x) => println!("{}", x),
         Ok(_) => println!("ok"),
     }
 }
-           "#,
+"#,
         );
     }
 
@@ -488,20 +468,15 @@ impl VariantData {
         check_assist(
             replace_match_with_if_let,
             r#"
-enum Option<T> { Some(T), None }
-use Option::*;
-
+//- minicore: option
 fn foo(x: Option<i32>) {
     $0match x {
         Some(x) => println!("{}", x),
         None => println!("none"),
     }
 }
-           "#,
+"#,
             r#"
-enum Option<T> { Some(T), None }
-use Option::*;
-
 fn foo(x: Option<i32>) {
     if let Some(x) = x {
         println!("{}", x)
@@ -509,7 +484,7 @@ fn foo(x: Option<i32>) {
         println!("none")
     }
 }
-           "#,
+"#,
         );
     }
 
@@ -518,20 +493,15 @@ fn foo(x: Option<i32>) {
         check_assist(
             replace_match_with_if_let,
             r#"
-enum Result<T, E> { Ok(T), Err(E) }
-use Result::*;
-
+//- minicore: result
 fn foo(x: Result<i32, ()>) {
     $0match x {
         Ok(x) => println!("{}", x),
         Err(_) => println!("none"),
     }
 }
-           "#,
+"#,
             r#"
-enum Result<T, E> { Ok(T), Err(E) }
-use Result::*;
-
 fn foo(x: Result<i32, ()>) {
     if let Ok(x) = x {
         println!("{}", x)
@@ -539,7 +509,7 @@ fn foo(x: Result<i32, ()>) {
         println!("none")
     }
 }
-           "#,
+"#,
         );
     }
 
diff --git a/crates/ide_assists/src/handlers/replace_unwrap_with_match.rs b/crates/ide_assists/src/handlers/replace_unwrap_with_match.rs
index a3bfa221c..f39c48d8f 100644
--- a/crates/ide_assists/src/handlers/replace_unwrap_with_match.rs
+++ b/crates/ide_assists/src/handlers/replace_unwrap_with_match.rs
@@ -20,17 +20,16 @@ use ide_db::ty_filter::TryEnum;
 // Replaces `unwrap` with a `match` expression. Works for Result and Option.
 //
 // ```
-// enum Result<T, E> { Ok(T), Err(E) }
+// # //- minicore: result
 // fn main() {
-//     let x: Result<i32, i32> = Result::Ok(92);
+//     let x: Result<i32, i32> = Ok(92);
 //     let y = x.$0unwrap();
 // }
 // ```
 // ->
 // ```
-// enum Result<T, E> { Ok(T), Err(E) }
 // fn main() {
-//     let x: Result<i32, i32> = Result::Ok(92);
+//     let x: Result<i32, i32> = Ok(92);
 //     let y = match x {
 //         Ok(it) => it,
 //         $0_ => unreachable!(),
@@ -97,25 +96,24 @@ mod tests {
     fn test_replace_result_unwrap_with_match() {
         check_assist(
             replace_unwrap_with_match,
-            r"
-enum Result<T, E> { Ok(T), Err(E) }
+            r#"
+//- minicore: result
 fn i<T>(a: T) -> T { a }
 fn main() {
-    let x: Result<i32, i32> = Result::Ok(92);
+    let x: Result<i32, i32> = Ok(92);
     let y = i(x).$0unwrap();
 }
-            ",
-            r"
-enum Result<T, E> { Ok(T), Err(E) }
+"#,
+            r#"
 fn i<T>(a: T) -> T { a }
 fn main() {
-    let x: Result<i32, i32> = Result::Ok(92);
+    let x: Result<i32, i32> = Ok(92);
     let y = match i(x) {
         Ok(it) => it,
         $0_ => unreachable!(),
     };
 }
-            ",
+"#,
         )
     }
 
@@ -123,25 +121,24 @@ fn main() {
     fn test_replace_option_unwrap_with_match() {
         check_assist(
             replace_unwrap_with_match,
-            r"
-enum Option<T> { Some(T), None }
+            r#"
+//- minicore: option
 fn i<T>(a: T) -> T { a }
 fn main() {
-    let x = Option::Some(92);
+    let x = Some(92);
     let y = i(x).$0unwrap();
 }
-            ",
-            r"
-enum Option<T> { Some(T), None }
+"#,
+            r#"
 fn i<T>(a: T) -> T { a }
 fn main() {
-    let x = Option::Some(92);
+    let x = Some(92);
     let y = match i(x) {
         Some(it) => it,
         $0_ => unreachable!(),
     };
 }
-            ",
+"#,
         );
     }
 
@@ -149,25 +146,24 @@ fn main() {
     fn test_replace_result_unwrap_with_match_chaining() {
         check_assist(
             replace_unwrap_with_match,
-            r"
-enum Result<T, E> { Ok(T), Err(E) }
+            r#"
+//- minicore: result
 fn i<T>(a: T) -> T { a }
 fn main() {
-    let x: Result<i32, i32> = Result::Ok(92);
+    let x: Result<i32, i32> = Ok(92);
     let y = i(x).$0unwrap().count_zeroes();
 }
-            ",
-            r"
-enum Result<T, E> { Ok(T), Err(E) }
+"#,
+            r#"
 fn i<T>(a: T) -> T { a }
 fn main() {
-    let x: Result<i32, i32> = Result::Ok(92);
+    let x: Result<i32, i32> = Ok(92);
     let y = match i(x) {
         Ok(it) => it,
         $0_ => unreachable!(),
     }.count_zeroes();
 }
-            ",
+"#,
         )
     }
 
@@ -175,14 +171,14 @@ fn main() {
     fn replace_unwrap_with_match_target() {
         check_assist_target(
             replace_unwrap_with_match,
-            r"
-enum Option<T> { Some(T), None }
+            r#"
+//- minicore: option
 fn i<T>(a: T) -> T { a }
 fn main() {
-    let x = Option::Some(92);
+    let x = Some(92);
     let y = i(x).$0unwrap();
 }
-            ",
+"#,
             r"i(x).unwrap()",
         );
     }