test: add tests for fixing edition and edition idioms

Signed-off-by: Rustin170506 <techregister@pm.me>

Author: 0xPoe

tests/testsuite/fix.rs

@@ -197,6 +197,103 @@ fn prepare_for_2018() {
         .contains("let x = crate::foo::FOO;"));
 }
 
+#[cargo_test]
+fn fix_tests_with_edition() {
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                [package]
+                name = "foo"
+                version = "0.1.0"
+                edition = "2018"
+            "#,
+        )
+        .file(
+            "src/lib.rs",
+            r#"
+                #![allow(ellipsis_inclusive_range_patterns)]
+                pub fn foo() {}
+
+                #[cfg(test)]
+                mod tests {
+                    #[test]
+                    fn it_works() {
+                        f();
+                    }
+                    fn f() -> bool {
+                        let x = 123;
+                        match x {
+                            0...100 => true,
+                            _ => false,
+                        }
+                    }
+                }
+            "#,
+        )
+        .build();
+
+    p.cargo("fix --edition --allow-no-vcs")
+        .with_stderr_data(str![[r#"
+[MIGRATING] Cargo.toml from 2018 edition to 2021
+[CHECKING] foo v0.1.0 ([ROOT]/foo)
+[MIGRATING] src/lib.rs from 2018 edition to 2021
+[FIXED] src/lib.rs (1 fix)
+[FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
+
+"#]])
+        .with_stdout_data("")
+        .run();
+    // Check that the test is fixed.
+    assert!(p.read_file("src/lib.rs").contains(r#"0..=100 => true,"#));
+}
+
+#[cargo_test]
+fn fix_tests_with_edition_idioms() {
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                [package]
+                name = 'foo'
+                version = '0.1.0'
+                edition = '2018'
+            "#,
+        )
+        .file(
+            "src/lib.rs",
+            r#"
+                pub fn foo() {}
+
+                #[cfg(test)]
+                mod tests {
+                    #[test]
+                    fn it_works() {
+                        f();
+                    }
+
+                    use std::any::Any;
+                    pub fn f() {
+                        let _x: Box<Any> = Box::new(3);
+                    }
+                }
+            "#,
+        )
+        .build();
+
+    p.cargo("fix --edition-idioms --allow-no-vcs")
+        .with_stderr_data(str![[r#"
+[CHECKING] foo v0.1.0 ([ROOT]/foo)
+[FIXED] src/lib.rs (1 fix)
+[FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
+
+"#]])
+        .with_stdout_data("")
+        .run();
+    // Check that the test is fixed.
+    assert!(p.read_file("src/lib.rs").contains("Box<dyn Any>"));
+}
+
 #[cargo_test]
 fn local_paths() {
     let p = project()