Safely escape files with backticks

1 files changed, 60 insertions, 1 deletions

diff --git a/src/renderer.rs b/src/renderer.rs
index 518abd8..4965963 100644
--- a/src/renderer.rs
+++ b/src/renderer.rs
@@ -4,11 +4,32 @@ pub fn render(project_name: &str, files: &[(&str, &str)]) -> String {
         output.push_str("\n## Files\n");
     }
     for (filename, content) in files {
-        output.push_str(&format!("\n### {}\n```\n{}\n```\n", filename, content));
+        let outer_backticks = outer_backticks(content);
+        output.push_str(&format!(
+            "\n### {}\n{}\n{}\n{}\n",
+            filename, outer_backticks, content, outer_backticks
+        ));
     }
     output
 }
 
+fn outer_backticks(contents: &str) -> String {
+    let mut max_ticks = 0;
+    let mut current_count = 0;
+    for char in contents.chars() {
+        if char == '`' {
+            current_count += 1;
+            if current_count > max_ticks {
+                max_ticks = current_count;
+            }
+        } else {
+            current_count = 0;
+        }
+    }
+    let fence_len = std::cmp::max(3, max_ticks + 1);
+    "`".repeat(fence_len)
+}
+
 #[cfg(test)]
 mod tests {
     use super::render;
@@ -35,4 +56,42 @@ mod tests {
             ```\n"
         );
     }
+
+    #[test]
+    fn multiple_files_are_rendered_in_order() {
+        let files = vec![("main.rs", "fn main() {}"), ("lib.rs", "pub fn hello() {}")];
+
+        let output = render("Project name", &files);
+
+        assert_eq!(
+            output,
+            "# Project name\n\n\
+            ## Files\n\n\
+            ### main.rs\n\
+            ```\n\
+            fn main() {}\n\
+            ```\n\n\
+            ### lib.rs\n\
+            ```\n\
+            pub fn hello() {}\n\
+            ```\n"
+        );
+    }
+
+    #[test]
+    fn file_with_backticks_is_handled_safely() {
+        let files = vec![("example.rs", "fn main() { println!(\"``` inside\"); }")];
+
+        let output = render("Project name", &files);
+
+        assert_eq!(
+            output,
+            "# Project name\n\n\
+            ## Files\n\n\
+            ### example.rs\n\
+            ````\n\
+            fn main() { println!(\"``` inside\"); }\n\
+            ````\n"
+        );
+    }
 }