1 files changed, 15 insertions, 0 deletions
diff --git a/subplotlib/src/steplibrary/files.rs b/subplotlib/src/steplibrary/files.rs
index fd84e1c..b94155f 100644
--- a/subplotlib/src/steplibrary/files.rs
+++ b/subplotlib/src/steplibrary/files.rs
@@ -232,6 +232,21 @@ pub fn file_contains(context: &Datadir, filename: &str, data: &str) {
     }
 }
 
+/// Check if a file lacks a given sequence of characters
+///
+/// # `then file (?P<filename>\S+) does not contain "(?P<data>.*)"`
+///
+/// This will load the content of the named file and ensure it lacks the given string.
+/// Note: this assumes everything is utf-8 encoded.  If not, things will fail.
+#[step]
+pub fn file_doesnt_contain(context: &Datadir, filename: &str, data: &str) {
+    let full_path = context.canonicalise_filename(filename)?;
+    let body = fs::read_to_string(full_path)?;
+    if body.contains(data) {
+        throw!("unexpected file content found");
+    }
+}
+
 /// Check if a file's content matches the given regular expression
 ///
 /// # `then file (?P<filename>\S+) matches regex /(?P<regex>.*)/`