Auto merge of #5958 - mikerite:fix-fmt-20200825, r=flip1995

Various fmt test improvements

Various fmt test improvements.

changelog: none

Author: bors

.cargo/config

@@ -1,6 +1,6 @@
 [alias]
 uitest = "test --test compile-test"
-dev = "run --package clippy_dev --bin clippy_dev --manifest-path clippy_dev/Cargo.toml --"
+dev = "run --target-dir clippy_dev/target --package clippy_dev --bin clippy_dev --manifest-path clippy_dev/Cargo.toml --"
 
 [build]
 rustflags = ["-Zunstable-options"]

tests/fmt.rs

@@ -7,7 +7,7 @@ fn fmt() {
         return;
     }
 
-    // Skip this test if rustup nightly is unavailable
+    // Skip this test if nightly rustfmt is unavailable
     let rustup_output = Command::new("rustup")
         .args(&["component", "list", "--toolchain", "nightly"])
         .output()
@@ -19,12 +19,9 @@ fn fmt() {
     }
 
     let root_dir = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
-    let dev_dir = root_dir.join("clippy_dev");
-    let target_dir = root_dir.join("target");
-    let target_dir = target_dir.to_str().unwrap();
     let output = Command::new("cargo")
-        .current_dir(dev_dir)
-        .args(&["+nightly", "run", "--target-dir", target_dir, "--", "fmt", "--check"])
+        .current_dir(root_dir)
+        .args(&["dev", "fmt", "--check"])
         .output()
         .unwrap();