chore: add additional test

crates/rome_cli/tests/main.rs

@@ -819,6 +819,54 @@ mod format {
         assert_cli_snapshot(module_path!(), "applies_custom_configuration", fs, console);
     }
 
+    #[test]
+    fn applies_custom_configuration_over_config_file() {
+        let mut fs = MemoryFileSystem::default();
+        let mut console = BufferConsole::default();
+
+        let file_path = Path::new("rome.json");
+        fs.insert(file_path.into(), CONFIG_FORMAT.as_bytes());
+
+        let file_path = Path::new("file.js");
+        fs.insert(file_path.into(), CUSTOM_CONFIGURATION_BEFORE.as_bytes());
+
+        let result = run_cli(
+            DynRef::Borrowed(&mut fs),
+            DynRef::Borrowed(&mut console),
+            Arguments::from_vec(vec![
+                OsString::from("format"),
+                OsString::from("--line-width"),
+                OsString::from("10"),
+                OsString::from("--indent-style"),
+                OsString::from("space"),
+                OsString::from("--indent-size"),
+                OsString::from("8"),
+                OsString::from("--write"),
+                file_path.as_os_str().into(),
+            ]),
+        );
+
+        assert!(result.is_ok(), "run_cli returned {result:?}");
+
+        let mut file = fs
+            .open(file_path)
+            .expect("formatting target file was removed by the CLI");
+
+        let mut content = String::new();
+        file.read_to_string(&mut content)
+            .expect("failed to read file from memory FS");
+
+        assert_eq!(content, CUSTOM_CONFIGURATION_AFTER);
+
+        drop(file);
+        assert_cli_snapshot(
+            module_path!(),
+            "applies_custom_configuration_over_config_file",
+            fs,
+            console,
+        );
+    }
+
     #[test]
     fn applies_custom_quote_style() {
         let mut fs = MemoryFileSystem::default();

crates/rome_cli/tests/snapshots/main_format/applies_custom_configuration_over_config_file.snap

@@ -0,0 +1,33 @@
+---
+source: crates/rome_cli/tests/snap_test.rs
+expression: content
+---
+## `rome.json`
+
+```json
+{
+  "formatter": {
+    "enabled": true,
+    "lineWidth": 160,
+    "indentStyle": "space",
+    "indentSize": 6
+  }
+}
+
+```
+
+## `file.js`
+
+```js
+function f() {
+        return {
+                a,
+                b,
+        };
+}
+
+```
+
+# Emitted Messages
+
+