fix(rustfmt): load nested out-of-line mods correctly

2 files changed, 26 insertions, 0 deletions

diff --git a/src/test/mod.rs b/src/test/mod.rs
index ce56a223f2b..cb52346a13a 100644
--- a/src/test/mod.rs
+++ b/src/test/mod.rs
@@ -16,6 +16,7 @@ use crate::source_file;
 use crate::{is_nightly_channel, FormatReport, FormatReportFormatterBuilder, Input, Session};
 
 mod configuration_snippet;
+mod mod_resolver;
 mod parser;
 
 const DIFF_CONTEXT_SIZE: usize = 3;
diff --git a/src/test/mod_resolver.rs b/src/test/mod_resolver.rs
new file mode 100644
index 00000000000..e0b55e3efb2
--- /dev/null
+++ b/src/test/mod_resolver.rs
@@ -0,0 +1,25 @@
+use std::io;
+use std::path::PathBuf;
+
+use super::read_config;
+
+use crate::{FileName, Input, Session};
+
+#[test]
+fn nested_out_of_line_mods_loaded() {
+    // See also https://github.com/rust-lang/rustfmt/issues/4874
+    let filename = "tests/mod-resolver/issue-4874/main.rs";
+    let input_file = PathBuf::from(filename);
+    let config = read_config(&input_file);
+    let mut session = Session::<io::Stdout>::new(config, None);
+    let report = session
+        .format(Input::File(filename.into()))
+        .expect("Should not have had any execution errors");
+    let errors_by_file = &report.internal.borrow().0;
+    assert!(errors_by_file.contains_key(&FileName::Real(PathBuf::from(
+        "tests/mod-resolver/issue-4874/bar/baz.rs",
+    ))));
+    assert!(errors_by_file.contains_key(&FileName::Real(PathBuf::from(
+        "tests/mod-resolver/issue-4874/foo/qux.rs",
+    ))));
+}