Improved handling of control characters in inline snapshots

Fixes at least some of #712 (not confident it fixes all of it, but wanted to get it out quickly)

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 All notable changes to insta and cargo-insta are documented here.
 
+## 1.42.1
+
+- Improved handling of control characters in inline snapshots.  #713
+
 ## 1.42.0
 
 - Text snapshots no longer contain `snapshot_type: text` in their metadata.  For

insta/src/snapshot.rs

@@ -689,8 +689,11 @@ impl TextSnapshotContents {
         let contents = self.normalize();
         let mut out = String::new();
 
-        // We don't technically need to escape on newlines, but it reduces diffs
-        let is_escape = contents.contains(['\\', '"', '\n']);
+        // We don't technically need to escape on newlines, but it reduces
+        // diffs (and is included in `is_control`).
+        let is_escape = contents
+            .chars()
+            .any(|c| matches!(c, '"' | '\\') || c.is_control());
         // Escape the string if needed, with `r#`, using the required number of `#`s
         let delimiter = if is_escape {
             out.push('r');
@@ -796,6 +799,12 @@ fn test_required_hashes() {
     assert_snapshot!(required_hashes("####"), @"0");
     assert_snapshot!(required_hashes(r###"\"\"##\"\""###), @"3");
     assert_snapshot!(required_hashes(r###"r"#"Raw string"#""###), @"2");
+    assert_snapshot!(required_hashes("foo\rbar"), @"0");
+    assert_snapshot!(required_hashes("foo\tbar"), @"0");
+    assert_snapshot!(required_hashes("foo\0bar"), @"0");
+    assert_snapshot!(required_hashes("foo\x1bbar"), @"0"); // ESC character
+    assert_snapshot!(required_hashes("foo\u{1234}bar"), @"0");
+    assert_snapshot!(required_hashes("foo\nbar"), @"0");
 }
 
 fn count_leading_spaces(value: &str) -> usize {