Test cfg_match! support

Author: CAD97

src/test/mod.rs

@@ -42,6 +42,8 @@ const FILE_SKIP_LIST: &[&str] = &[
     "issue-3253/foo.rs",
     "issue-3253/bar.rs",
     "issue-3253/paths",
+    // This directory is directly tested by format_files_find_new_files_via_cfg_match
+    "cfg_match",
     // These files and directory are a part of modules defined inside `cfg_attr(..)`.
     "cfg_mod/dir",
     "cfg_mod/bar.rs",
@@ -468,6 +470,45 @@ fn format_files_find_new_files_via_cfg_if() {
     });
 }
 
+#[test]
+fn format_files_find_new_files_via_cfg_match() {
+    init_log();
+    run_test_with(&TestSetting::default(), || {
+        // We load these two files into the same session to test cfg_match!
+        // transparent mod discovery, and to ensure that it does not suffer
+        // from a similar issue as cfg_if! support did with issue-4656.
+        let files = vec![
+            Path::new("tests/source/cfg_match/lib2.rs"),
+            Path::new("tests/source/cfg_match/lib.rs"),
+        ];
+
+        let config = Config::default();
+        let mut session = Session::<io::Stdout>::new(config, None);
+
+        let mut write_result = HashMap::new();
+        for file in files {
+            assert!(file.exists());
+            let result = session.format(Input::File(file.into())).unwrap();
+            assert!(!session.has_formatting_errors());
+            assert!(!result.has_warnings());
+            let mut source_file = SourceFile::new();
+            mem::swap(&mut session.source_file, &mut source_file);
+
+            for (filename, text) in source_file {
+                if let FileName::Real(ref filename) = filename {
+                    write_result.insert(filename.to_owned(), text);
+                }
+            }
+        }
+        assert_eq!(
+            3,
+            write_result.len(),
+            "Should have uncovered an extra file (format_me_please.rs) via lib.rs"
+        );
+        assert!(handle_result(write_result, None).is_ok());
+    });
+}
+
 #[test]
 fn stdin_formatting_smoke_test() {
     init_log();

tests/source/cfg_match/format_me_please.rs

@@ -0,0 +1,2 @@
+
+pub fn     hello(   )  {     }

tests/source/cfg_match/lib.rs

@@ -0,0 +1,5 @@
+std::cfg_match! {
+    target_family = "unix" => {
+        mod format_me_please;
+    }
+}

tests/source/cfg_match/lib2.rs

@@ -0,0 +1,3 @@
+its_a_macro! {
+    // Contents
+}

tests/target/cfg_match/format_me_please.rs

@@ -0,0 +1 @@
+pub fn hello() {}

tests/target/cfg_match/lib.rs

@@ -0,0 +1,5 @@
+std::cfg_match! {
+    target_family = "unix" => {
+        mod format_me_please;
+    }
+}

tests/target/cfg_match/lib2.rs

@@ -0,0 +1,3 @@
+its_a_macro! {
+    // Contents
+}