From cfd03ee39e5fd5bef42e1de229a0868fae909c33 Mon Sep 17 00:00:00 2001
From: Lars Wirzenius <liw@liw.fi>
Date: Sun, 5 Dec 2021 21:01:44 +0200
Subject: feat: create a temporary directory for test data

Sponsored-by: author
---
 Cargo.lock                 |  1 +
 Cargo.toml                 |  1 +
 src/bin/obnam-benchmark.rs |  2 +-
 src/data.rs                | 13 +++++++++----
 src/state.rs               | 20 ++++++++++++++------
 5 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index bd4e55c..3673319 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -587,6 +587,7 @@ dependencies = [
  "structopt",
  "subplot-build",
  "subplotlib",
+ "tempfile",
  "thiserror",
 ]
 
diff --git a/Cargo.toml b/Cargo.toml
index 2979f4d..79ea8d2 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -12,6 +12,7 @@ serde = { version = "1.0.101", features = ["derive"] }
 serde_json = "1.0.72"
 serde_yaml = "0.8.21"
 structopt = "0.3.25"
+tempfile = "3.2.0"
 thiserror = "1.0.30"
 
 [build-dependencies]
diff --git a/src/bin/obnam-benchmark.rs b/src/bin/obnam-benchmark.rs
index 418a46e..0ad8491 100644
--- a/src/bin/obnam-benchmark.rs
+++ b/src/bin/obnam-benchmark.rs
@@ -53,7 +53,7 @@ struct Run {
 impl Run {
     fn run(&self) -> anyhow::Result<()> {
         let spec = Specification::from_file(&self.spec)?;
-        let mut state = State::new();
+        let mut state = State::new()?;
         let mut result = Result::default();
         for step in spec.steps() {
             if let Some(m) = state.execute(&step)? {
diff --git a/src/data.rs b/src/data.rs
index aaaebc9..04376bc 100644
--- a/src/data.rs
+++ b/src/data.rs
@@ -1,4 +1,5 @@
 use crate::specification::{Create, FileCount};
+use std::path::{Path, PathBuf};
 
 /// Test data management for Obnam benchmarks.
 ///
@@ -6,7 +7,9 @@ use crate::specification::{Create, FileCount};
 /// that backup. That data is later cleaned up. Is all handled by this
 /// structure.
 #[derive(Debug)]
-pub struct Data {}
+pub struct Data {
+    tempdir: PathBuf,
+}
 
 /// Possible errors from managing data.
 #[derive(Debug, thiserror::Error)]
@@ -14,12 +17,14 @@ pub enum DataError {
 }
 
 impl Data {
-    pub(crate) fn new() -> Result<Self, DataError> {
-        Ok(Self {})
+    pub(crate) fn new(tempdir: &Path) -> Result<Self, DataError> {
+        Ok(Self {
+            tempdir: tempdir.to_path_buf(),
+        })
     }
 
     pub(crate) fn create(&self, create: &Create) -> Result<(), DataError> {
-        println!("create {:?}", create);
+        println!("create {:?} in {}", create, self.tempdir.display());
         Ok(())
     }
 
diff --git a/src/state.rs b/src/state.rs
index bce5115..b925656 100644
--- a/src/state.rs
+++ b/src/state.rs
@@ -2,10 +2,13 @@ use crate::data::{Data, DataError};
 use crate::result::{Measurement, OpMeasurements, Operation};
 use crate::step::Step;
 use std::time::Instant;
+use std::path::{Path};
+use tempfile::{tempdir, TempDir};
 
 /// Runtime state for running Obnam benchmarks.
 pub struct State {
     current_benchmark: Option<CurrentBenchmark>,
+    tempdir: TempDir,
 }
 
 /// Possible errors from changing benchmark state.
@@ -15,16 +18,21 @@ pub enum StateError {
     #[error("Internal error: step expected inside a benchmark")]
     OutOfStep,
 
+    /// Failed to create a temporary directory.
+    #[error(transparent)]
+    CreateTemp(#[from] std::io::Error),
+
     /// Error managing test data.
     #[error(transparent)]
     Data(#[from] DataError),
 }
 
 impl State {
-    pub fn new() -> Self {
-        Self {
+    pub fn new() -> Result<Self, StateError> {
+        Ok(Self {
             current_benchmark: None,
-        }
+            tempdir: tempdir()?,
+        })
     }
 
     fn current(&self) -> Result<&CurrentBenchmark, StateError> {
@@ -39,7 +47,7 @@ impl State {
         let now = Instant::now();
         let om = match step {
             Step::Start(name) => {
-                self.current_benchmark = Some(CurrentBenchmark::new(name)?);
+                self.current_benchmark = Some(CurrentBenchmark::new(name, self.tempdir.path())?);
                 None
             }
             Step::Stop(_) => {
@@ -93,10 +101,10 @@ struct CurrentBenchmark {
 }
 
 impl CurrentBenchmark {
-    fn new(name: &str) -> Result<Self, DataError> {
+    fn new(name: &str, tempdir: &Path) -> Result<Self, DataError> {
         Ok(Self {
             name: name.to_string(),
-            data: Data::new()?,
+            data: Data::new(tempdir)?,
         })
     }
 }
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