refactor: tests: port multi_rewrite to a snapshot test

`git` didn't recognize this as a pure move, but it is.

This test was supposed to test if changes are visible across `commit`s,
even when those changes aren't written to the original file
(like with the `--rewrite-mode alongside` used by [`refactor`],
and unlike with `--rewrite-mode inplace`).
However, `commit` is currently broken (see #1605),
so this test is not actually testing what it's meant to.
The places where `commit`s are supposed to go
are left as comments for now until we fix `commit`.

Author: kkysen

c2rust-refactor/tests/multi_rewrite/new.rs

@@ -327,6 +327,28 @@ fn test_matcher_typed() {
         .test();
 }
 
+/// This test was supposed to test if changes are visible across `commit`s,
+/// even when those changes aren't written to the original file
+/// (like with the `--rewrite-mode alongside` used by [`refactor`],
+/// and unlike with `--rewrite-mode inplace`).
+/// However, `commit` is currently broken (see #1605),
+/// so this test is not actually testing what it's meant to.
+/// The places where `commit`s are supposed to go
+/// are left as comments for now until we fix `commit`.
+#[test]
+fn test_multi_rewrite() {
+    refactor("rewrite_expr")
+        .command_args(&["1", "2"])
+        .named("multi_rewrite.rs")
+        .test();
+    // commit
+    refactor("rewrite_expr")
+        .command_args(&["2", "3"])
+        .named("multi_rewrite.new")
+        .test();
+    // commit
+}
+
 /// TODO Broken.
 /// This panics with the error:
 ///

c2rust-refactor/tests/multi_rewrite/run.sh

@@ -0,0 +1,7 @@
+---
+source: c2rust-refactor/tests/snapshots.rs
+expression: c2rust-refactor rewrite_expr 2 3 --rewrite-mode alongside -- tests/snapshots/multi_rewrite.new --edition 2021
+---
+fn main() {
+    let x = 3;
+}

c2rust-refactor/tests/snapshots.rs

@@ -0,0 +1,7 @@
+---
+source: c2rust-refactor/tests/snapshots.rs
+expression: c2rust-refactor rewrite_expr 1 2 --rewrite-mode alongside -- tests/snapshots/multi_rewrite.rs --edition 2021
+---
+fn main() {
+    let x = 2;
+}