1 files changed, 17 insertions, 0 deletions
diff --git a/subplot/benchmark.rs b/subplot/benchmark.rs
index 566ce30..082e02b 100644
--- a/subplot/benchmark.rs
+++ b/subplot/benchmark.rs
@@ -72,3 +72,20 @@ fn read_json_file(filename: &Path) -> anyhow::Result<Value> {
     let file = File::open(filename)?;
     Ok(serde_json::from_reader(&file)?)
 }
+
+#[step]
+#[context(Datadir)]
+#[context(SubplotContext)]
+fn file_is_at_least_this_long(context: &ScenarioContext, filename: &str, number: u64) {
+    context.with(
+        |context: &Datadir| {
+            let filename = context.canonicalise_filename(&filename)?;
+            let meta = std::fs::metadata(&filename)?;
+            if meta.len() < number {
+                panic!("file is {} bytes, wanted at least {} bytes", meta.len(), number);
+            }
+            Ok(())
+        },
+        false,
+    )?;
+}