Only pass --color if not always to work around custom runners (#491)

CHANGELOG.md

@@ -5,10 +5,16 @@ All notable changes to insta and cargo-insta are documented here.
 ## 1.39.0
 
 - Fixed a bug in `require_full_match`.  #485
+
 - Fixed a bug that caused snapshot and module names to sometimes be inaccurate.  #483
+
 - Insta will no longer error when removing snapshots that were already removed.  #484
+
 - Added support for trailing commas in inline snapshots.  #472
 
+- Don't pass `--color` in all cases to `libtest` any more to work around limitations
+  with custom test harnesses.  #491
+
 ## 1.38.0
 
 - `Filters` is now constructible from `IntoIterator`.  #400

cargo-insta/src/cli.rs

@@ -954,11 +954,11 @@ fn prepare_test_runner<'snapshot_ref>(
     // Currently libtest uses a different approach to color, so we need to pass
     // it again to get output from the test runner as well as cargo. See
     // https://github.com/rust-lang/cargo/issues/1983 for more
-    match test_runner {
-        TestRunner::CargoTest | TestRunner::Auto => {
-            proc.arg(format!("--color={}", color));
-        }
-        _ => {}
+    // We also only want to do this if we override auto as some custom test runners
+    // do not handle --color and then we at least fix the default case.
+    // https://github.com/mitsuhiko/insta/issues/473
+    if color != "auto" && matches!(test_runner, TestRunner::CargoTest | TestRunner::Auto) {
+        proc.arg(format!("--color={}", color));
     };
     Ok((proc, snapshot_ref_file, prevents_doc_run))
 }