BUGFIX: CreateOrInsertIntoFile was not reverting (#180)

* BUGFIX: CreateOrInsertIntoFile was not reverting

* ci prod

* Fixup file naming

* Fix tempdir naming

* fixup

* In a module

* truncate

src/action/base/create_or_insert_into_file.rs

@@ -244,7 +244,7 @@ impl Action for CreateOrInsertIntoFile {
             file_contents.replace_range(start..end, "")
         }
 
-        if buf.is_empty() {
+        if file_contents.is_empty() {
             remove_file(&path)
                 .await
                 .map_err(|e| ActionError::Remove(path.to_owned(), e))?;
@@ -252,10 +252,79 @@ impl Action for CreateOrInsertIntoFile {
             file.seek(SeekFrom::Start(0))
                 .await
                 .map_err(|e| ActionError::Seek(path.to_owned(), e))?;
+            file.set_len(0)
+                .await
+                .map_err(|e| ActionError::Truncate(path.to_owned(), e))?;
             file.write_all(file_contents.as_bytes())
                 .await
                 .map_err(|e| ActionError::Write(path.to_owned(), e))?;
+            file.flush()
+                .await
+                .map_err(|e| ActionError::Flush(path.to_owned(), e))?;
         }
         Ok(())
     }
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[tokio::test]
+    async fn creates_and_deletes_file() -> eyre::Result<()> {
+        let temp_dir = tempdir::TempDir::new("nix_installer_create_or_insert_into_file")?;
+        let test_file = temp_dir.path().join("creates_and_deletes_file");
+        let mut action = CreateOrInsertIntoFile::plan(
+            test_file.clone(),
+            None,
+            None,
+            None,
+            "Test".into(),
+            Position::Beginning,
+        )
+        .await?;
+
+        action.try_execute().await?;
+
+        action.try_revert().await?;
+
+        assert!(!test_file.exists(), "File should have been deleted");
+
+        Ok(())
+    }
+
+    #[tokio::test]
+    async fn edits_and_reverts_file() -> eyre::Result<()> {
+        let temp_dir = tempdir::TempDir::new("nix_installer_create_or_insert_into_file")?;
+        let test_file = temp_dir.path().join("edits_and_reverts_file");
+
+        let test_content = "Some other content";
+        tokio::fs::write(&test_file, test_content)
+            .await
+            .expect("Could not write to test temp file");
+
+        let mut action = CreateOrInsertIntoFile::plan(
+            test_file.clone(),
+            None,
+            None,
+            None,
+            "Test".into(),
+            Position::Beginning,
+        )
+        .await?;
+
+        action.try_execute().await?;
+
+        action.try_revert().await?;
+
+        assert!(test_file.exists(), "File should have not been deleted");
+
+        let read_content = tokio::fs::read_to_string(test_file)
+            .await
+            .expect("Could not read test temp file");
+
+        assert_eq!(test_content, read_content);
+
+        Ok(())
+    }
+}

src/action/mod.rs

@@ -298,6 +298,10 @@ pub enum ActionError {
     Write(std::path::PathBuf, #[source] std::io::Error),
     #[error("Seek path `{0}`")]
     Seek(std::path::PathBuf, #[source] std::io::Error),
+    #[error("Flushing `{0}`")]
+    Flush(std::path::PathBuf, #[source] std::io::Error),
+    #[error("Truncating `{0}`")]
+    Truncate(std::path::PathBuf, #[source] std::io::Error),
     #[error("Getting uid for user `{0}`")]
     UserId(String, #[source] nix::errno::Errno),
     #[error("Getting user `{0}`")]