fix: JSON should be set to "success": false when any transactions failed

libmamba/include/mamba/core/output.hpp

@@ -161,6 +161,25 @@ namespace mamba
         Console(const Context& context);
         ~Console();
 
+        /** Utility to set `"success": false` on destruction of this object
+            when it's destructor is invoked while an exception is in flight.
+
+            This helps avoiding situations where an exception that should be
+            considered a failure of the overall operation is thrown but
+            the json is still set with `"success": true`, while it should be `false`,
+            misleading the testing outputs.
+        */
+        struct JSonFailureOnException
+        {
+            ~JSonFailureOnException()
+            {
+                if (std::uncaught_exceptions() > 0)
+                {
+                    Console::instance().json_write({ { "success", false } });
+                }
+            }
+        };
+
     private:
 
         void json_print();

libmamba/src/core/transaction.cpp

@@ -367,6 +367,9 @@ namespace mamba
     bool
     MTransaction::execute(const Context& ctx, ChannelContext& channel_context, PrefixData& prefix)
     {
+        // If an exception exists this function, we must consider the whole operation a failure.
+        Console::JSonFailureOnException fail_json_on_exception;
+
         // JSON output
         // back to the top level if any action was required
         if (!empty())

micromamba/tests/test_pkg_cache.py

@@ -393,16 +393,15 @@ def test_no_writable_extracted_dir_corrupted(self, tmp_home, tmp_root_prefix, tm
                 f"**{file_to_find_in_package}", recursive=True, root_dir=old_cache_dir
             )
             for file in files:
-                (old_cache_dir / file).unlink()
+                file.unlink()
         helpers.recursive_chmod(tmp_cache, 0o500)
 
         os.environ["CONDA_PKGS_DIRS"] = f"{tmp_cache}"
 
-        # Mamba now handles corrupted extracted directories in read-only caches gracefully
-        # by extracting to a temporary location, so the operation should succeed
-        helpers.create(
-            "-n", "myenv", package_to_check_requirements(), "-vv", "--json", no_dry_run=True
-        )
+        with pytest.raises(subprocess.CalledProcessError):
+            helpers.create(
+                "-n", "myenv", package_to_check_requirements(), "-vv", "--json", no_dry_run=True
+            )
 
     def test_first_writable_extracted_dir_corrupted(
         self, tmp_home, tmp_root_prefix, tmp_cache, tmp_cache_alt