fix(fmt): --check was broken for CSS, YAML and HTML (#25848)

`deno fmt --check` was broken for CSS, YAML and HTML files.

Before this PR, formatting any of these file types would return a
string, even though the contract in `cli/tools/fmt.rs` is to only return a
string if the formatting changed. This causes wrong flagging of these files
as being badly formatted even though diffs showed nothing (because
they were in fact formatted properly).

Closes https://github.com/denoland/deno/issues/25840

1 files changed, 10 insertions, 2 deletions

diff --git a/tests/specs/fmt/css/__test__.jsonc b/tests/specs/fmt/css/__test__.jsonc
index e58818fbe..a3ded6d43 100644
--- a/tests/specs/fmt/css/__test__.jsonc
+++ b/tests/specs/fmt/css/__test__.jsonc
@@ -1,5 +1,13 @@
 {
   "tempDir": true,
-  "args": "fmt",
-  "output": "[WILDLINE]badly_formatted.css\nChecked 1 file\n"
+  "tests": {
+    "badly_formatted": {
+      "args": "fmt badly_formatted.css",
+      "output": "[WILDLINE]badly_formatted.css\nChecked 1 file\n"
+    },
+    "well_formatted": {
+      "args": "fmt --check well_formatted.css",
+      "output": "Checked 1 file\n"
+    }
+  }
 }