Add artifact writer

Summary: We write artifacts in several places through the TD. This unifies and dedupes them.

Reviewed By: ndmitchell

Differential Revision: D62555601

fbshipit-source-id: 613c36ba79ca771a90d2268cd6ef3f570c1aabd1

td_util/src/file_writer.rs

@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under both the MIT license found in the
+ * LICENSE-MIT file in the root directory of this source tree and the Apache
+ * License, Version 2.0 found in the LICENSE-APACHE file in the root directory
+ * of this source tree.
+ */
+
+use std::fs::OpenOptions;
+use std::io::BufWriter;
+use std::io::Write;
+use std::path::PathBuf;
+
+use anyhow::Context;
+
+pub fn file_writer(file_path: &PathBuf) -> anyhow::Result<impl Write> {
+    let file = OpenOptions::new()
+        .write(true)
+        .create(true)
+        .truncate(true)
+        .open(file_path)
+        .with_context(|| format!("Unable to open file `{}` for writing", file_path.display()))?;
+    Ok(BufWriter::new(file))
+}
+
+#[cfg(test)]
+mod tests {
+    use std::fs;
+    use std::io::Write;
+    use std::path::PathBuf;
+
+    use tempfile::TempDir;
+
+    use crate::file_writer::file_writer;
+
+    static DATA: &str = "Artifact data";
+
+    #[test]
+    pub fn test_write_success() {
+        let out_dir = TempDir::new().unwrap();
+        let out_path = out_dir.path().join("test_artifact.json");
+
+        file_writer(&out_path)
+            .unwrap()
+            .write_all(DATA.as_bytes())
+            .unwrap();
+
+        let written = fs::read_to_string(&out_path).unwrap();
+        assert_eq!(written, DATA);
+    }
+
+    #[test]
+    pub fn test_write_error() {
+        assert!(file_writer(&PathBuf::from("/invalid/file/path")).is_err());
+    }
+}

td_util/src/lib.rs

@@ -13,6 +13,7 @@ pub mod cli;
 pub mod command;
 pub mod directives;
 pub mod executor;
+pub mod file_writer;
 pub mod json;
 pub mod knobs;
 pub mod no_hash;