Implement file.write (#251)

docs/_docs/user-guide/eldritch.md

@@ -220,7 +220,8 @@ The <b>file.timestomp</b> method is very cool, and will be even cooler when Nick
 ### file.write
 `file.write(path: str, content: str) -> None`
 
-The <b>file.write</b> method is very cool, and will be even cooler when Nick documents it.
+The <b>file.write</b> method writes to a given file path with the given content.
+If a file or directory already exists at this path, the method will fail.
 
 ---
 

implants/lib/eldritch/src/file/write_impl.rs

@@ -1,5 +1,54 @@
-use anyhow::Result;
+use anyhow::{anyhow, Result};
+use std::{fs::File, io::Write, path::Path};
 
-pub fn write(_path: String, _content: String) -> Result<()> {
-    unimplemented!("Method unimplemented")
-}
+pub fn write(path: String, content: String) -> Result<()> {
+    if Path::new(&path).exists() {
+        return Err(anyhow!("File already exists"));
+    }
+    let mut f = File::create(&path).map_err(|err| anyhow!("File could not be created: {err}"))?;
+    f.write_all(content.as_bytes())
+        .map_err(|err| anyhow!("Failed to write to file: {err}"))?;
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tempfile::{tempdir, NamedTempFile};
+
+    #[test]
+    fn test_write_file_success() -> anyhow::Result<()> {
+        // Write to a file where we know it doesn't already exist
+        let tempdir = tempdir()?;
+        let path = tempdir
+            .path()
+            .join("writetest.txt")
+            .to_string_lossy()
+            .to_string();
+
+        assert!(write(path, "Hello World!".to_string()).is_ok());
+        tempdir.close()?;
+        Ok(())
+    }
+
+    #[test]
+    fn test_write_fail_file_exists() -> anyhow::Result<()> {
+        // Attempt to write to a file that already exists and fail
+        let tmp_file = NamedTempFile::new()?;
+        let path = String::from(tmp_file.path().to_str().unwrap()).clone();
+
+        assert!(write(path, "Hello World!".to_string()).is_err());
+        tmp_file.close()?;
+        Ok(())
+    }
+
+    #[test]
+    fn test_write_fail_directory_exists() -> anyhow::Result<()> {
+        // Attempt to write to a file that is currently a directory and fail
+        let dir = tempdir()?;
+        let path = String::from(dir.path().to_str().unwrap());
+
+        assert!(write(path, "Hello World!".to_string()).is_err());
+        Ok(())
+    }
+}