diff --git a/src/tests/graph.rs b/src/tests/graph.rs
index d454931..e8f1b53 100644
--- a/src/tests/graph.rs
+++ b/src/tests/graph.rs
@@ -13,6 +13,8 @@ type TestResult = Result<(), Box<dyn std::error::Error>>;
 
 const OUTPUT_DIR: &str = "./out/graph";
 const SNAPSHOT_DIR: &str = "./tests/graph";
+// Set this environment variable when Git repository output is needed for graph test debugging.
+const DUMP_GRAPH_TEST_REPOS_ENV: &str = "SERIE_TEST_DUMP_GRAPH_REPOS";
 
 #[test]
 fn straight_001() -> TestResult {
@@ -1506,6 +1508,10 @@ fn create_output_dirs(path: &str) {
 }
 
 fn copy_git_dir(path: &Path, name: &str) {
+    if std::env::var_os(DUMP_GRAPH_TEST_REPOS_ENV).is_none() {
+        return;
+    }
+
     let dst_path = format!("{OUTPUT_DIR}/{name}");
     // dircpy overwrite doesn't seem to work as expected, so delete explicitly
     if Path::new(&dst_path).is_dir() {