Add tests for some edition lints

cargo-fix/tests/all/edition_upgrade.rs

@@ -44,3 +44,127 @@ fn prepare_for_2018() {
     assert!(p.read("src/lib.rs").contains("use crate::foo::FOO;"));
     assert!(p.read("src/lib.rs").contains("let x = crate::foo::FOO;"));
 }
+
+#[test]
+fn local_paths() {
+    let p = project()
+        .file(
+            "src/lib.rs",
+            r#"
+                #![feature(rust_2018_preview)]
+
+                use test::foo;
+
+                mod test {
+                    pub fn foo() {}
+                }
+
+                pub fn f() {
+                    foo();
+                }
+            "#,
+        )
+        .build();
+
+    let stderr = "\
+[CHECKING] foo v0.1.0 (CWD)
+[FIXING] src/lib.rs (1 fix)
+[FINISHED] dev [unoptimized + debuginfo]
+";
+    p.expect_cmd("cargo-fix fix --prepare-for 2018")
+        .stdout("")
+        .stderr(stderr)
+        .run();
+
+    println!("{}", p.read("src/lib.rs"));
+    assert!(p.read("src/lib.rs").contains("use crate::test::foo;"));
+}
+
+#[test]
+fn local_paths_no_fix() {
+    let p = project()
+        .file(
+            "src/lib.rs",
+            r#"
+                use test::foo;
+
+                mod test {
+                    pub fn foo() {}
+                }
+
+                pub fn f() {
+                    foo();
+                }
+            "#,
+        )
+        .build();
+
+    let stderr = "\
+[CHECKING] foo v0.1.0 (CWD)
+[FINISHED] dev [unoptimized + debuginfo]
+";
+    p.expect_cmd("cargo-fix fix --prepare-for 2018")
+        .stdout("")
+        .stderr(stderr)
+        .run();
+}
+
+#[test]
+fn upgrade_extern_crate() {
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                cargo-features = ["edition"]
+
+                [package]
+                name = "foo"
+                version = "0.1.0"
+                edition = '2018'
+
+                [workspace]
+
+                [dependencies]
+                bar = { path = 'bar' }
+            "#,
+        )
+        .file(
+            "src/lib.rs",
+            r#"
+                #![warn(rust_2018_migration)]
+
+                extern crate bar;
+
+                use bar::bar;
+
+                pub fn foo() {
+                    ::bar::bar();
+                    bar();
+                }
+            "#,
+        )
+        .file(
+            "bar/Cargo.toml",
+            r#"
+                [package]
+                name = "bar"
+                version = "0.1.0"
+            "#,
+        )
+        .file("bar/src/lib.rs", "pub fn bar() {}")
+        .build();
+
+    let stderr = "\
+[CHECKING] bar v0.1.0 (CWD/bar)
+[CHECKING] foo v0.1.0 (CWD)
+[FIXING] src/lib.rs (1 fix)
+[FINISHED] dev [unoptimized + debuginfo]
+";
+    p.expect_cmd("cargo-fix fix")
+        .stdout("")
+        .stderr(stderr)
+        .run();
+
+    println!("{}", p.read("src/lib.rs"));
+    assert!(!p.read("src/lib.rs").contains("extern crate"));
+}