2 files changed, 46 insertions, 0 deletions
diff --git a/src/main.rs b/src/main.rs
index e7a11a9..bbea60f 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,3 +1,35 @@
+use std::io::{Read, Write};
+
+use repo2markdown::renderer::render;
+
 fn main() {
     println!("Hello, world!");
 }
+
+pub fn run<R: Read, W: Write>(mut input: R, mut output: W) -> Result<(), Box<dyn std::error::Error>> {
+    let mut buf = Vec::new();
+    input.read_to_end(&mut buf)?;
+    let rendered = render("Project name", &[])?;
+    output.write_all(rendered.as_bytes())?;
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::run;
+
+    #[test]
+    fn cli_with_empty_input_produces_empty_project() {
+        use std::io::Cursor;
+
+        let input = Cursor::new(b"");
+        let mut output = Vec::new();
+
+        run(input, &mut output).unwrap();
+
+        assert_eq!(
+            String::from_utf8(output).unwrap(),
+            "# Project name\n"
+        );
+    }
+}
diff --git a/src/renderer.rs b/src/renderer.rs
index 7162d1f..583730a 100644
--- a/src/renderer.rs
+++ b/src/renderer.rs
@@ -1,8 +1,22 @@
+use std::fmt;
+
 #[derive(Debug)]
 pub enum RenderError {
     BinaryFile(String),
 }
 
+impl fmt::Display for RenderError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            RenderError::BinaryFile(filename) => {
+                write!(f, "Binary file encountered: {}", filename)
+            }
+        }
+    }
+}
+
+impl std::error::Error for RenderError {}
+
 pub fn render(project_name: &str, files: &[(&str, &[u8])]) -> Result<String, RenderError> {
     let mut output = format!("# {}\n", project_name);
     if !files.is_empty() {