test: Fix `write_to_file` race condition

Have each `write_to_file` test pass in a custom filename to the helper
function. This way each test has its own file to deal with, eliminating
the race condition when running tests in parallel (the default).

1 files changed, 21 insertions, 16 deletions

diff --git a/src/tests.rs b/src/tests.rs
index f00d103..15b5ae8 100644
--- a/src/tests.rs
+++ b/src/tests.rs
@@ -122,23 +122,23 @@ fn update_alias_id_increments_alias() {
 }
 
 
-fn alias_write_to_file_helper<F>(alias: &mut Alias, f: F) -> String
+fn alias_write_to_file_helper<F>(alias: &mut Alias, filename: &str, f: F) -> String
     where F: Fn(&Alias, &str) {
     // Create a new test file
-    let test_file = "./testdata/write_to_file";
-    fs::copy("./testdata/aliases", test_file).expect("Alias file copy failed");
+    let test_file = format!("./testdata/{}", filename);
+    fs::copy("./testdata/aliases", &test_file).expect("Alias file copy failed");
 
-    f(alias, test_file);
+    f(alias, &test_file);
 
     // Write our new alias to the file
-    alias.write_to_file(test_file).expect("`write_to_file` failed");
+    alias.write_to_file(&test_file).expect("`write_to_file` failed");
 
     // Get the file's contents for testing
-    let mut f = File::open(test_file).expect("Failed to open test file");
+    let mut f = File::open(&test_file).expect("Failed to open test file");
     let mut file_contents = String::new();
     f.read_to_string(&mut file_contents).expect("Failed to read test file contents");
     let file_contents: Vec<&str> = file_contents.split('\n').collect();
-    fs::remove_file(test_file).expect("Failed to delete test file");
+    fs::remove_file(&test_file).expect("Failed to delete test file");
 
     file_contents[file_contents.len() - 2].to_string()
 }
@@ -146,15 +146,19 @@ fn alias_write_to_file_helper<F>(alias: &mut Alias, f: F) -> String
 #[test]
 fn alias_write_to_file_must_write_unique_alias_to_file_if_one_already_exists() {
     let mut alias = update_alias_id_sample_alias();
-    let alias_line = alias_write_to_file_helper(&mut alias, |alias: &Alias, filename: &str| {
-        // Write a duplicate alias so that `write_to_file` is able to append a
-        // new one
-        let mut f = OpenOptions::new().append(true).open(filename)
-            .expect("Failed to open test file for appending");
-        writeln!(f, "{}", Alias { email: "derpy@home.pv".to_owned(), .. alias.clone() }
-                .to_string())
-            .expect("Failed to append matching alias");
-    });
+    let alias_line = alias_write_to_file_helper(
+        &mut alias,
+        "alias_write_to_file_must_write_unique_alias_to_file_if_one_already_exists",
+        |alias: &Alias, filename: &str| {
+            // Write a duplicate alias so that `write_to_file` is able to append a
+            // new one
+            let mut f = OpenOptions::new().append(true).open(filename)
+                .expect("Failed to open test file for appending");
+            writeln!(f, "{}", Alias { email: "derpy@home.pv".to_owned(), .. alias.clone() }
+                    .to_string())
+                .expect("Failed to append matching alias");
+        }
+    );
 
     assert_eq!(alias.to_string(), alias_line);
 }
@@ -165,6 +169,7 @@ fn alias_write_to_file_must_write_given_alias_to_file() {
     let mut alias = update_alias_id_sample_alias();
     let alias_line = alias_write_to_file_helper(
         &mut alias,
+        "alias_write_to_file_must_write_given_alias_to_file",
         |alias: &Alias, filename: &str| {});
 
     assert_eq!(alias.to_string(), alias_line);