Rework custom_build_name test to use a fixture

Instead of creating a new package on the fly

fixtures/custom_build_name/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "custom_build_name"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+build = "custom_build_name.rs"

fixtures/custom_build_name/custom_build_name.rs

@@ -0,0 +1 @@
+../../tests/cases/ping.rs

fixtures/custom_build_name/src/lib.rs

@@ -0,0 +1 @@
+

tests/custom_build_name.rs

@@ -1,18 +1,13 @@
-use anyhow::Result;
-use std::{
-    fs::{copy, create_dir, write},
-    path::Path,
-};
-use tempfile::{tempdir, TempDir};
+use std::path::Path;
 
 pub mod util;
 
 #[test]
 fn custom_build_name() {
-    let temp_package = temp_package(Path::new("tests/cases/ping.rs")).unwrap();
+    let dir = Path::new("fixtures/custom_build_name");
 
     let mut command = util::build_with_build_wrap();
-    command.current_dir(&temp_package);
+    command.current_dir(dir);
 
     let output = util::exec(command, false).unwrap();
     assert!(!output.status.success());
@@ -23,28 +18,3 @@ fn custom_build_name() {
         "stderr does not contain expected string:\n```\n{stderr}\n```",
     );
 }
-
-#[allow(clippy::disallowed_methods)]
-fn temp_package(build_script_path: &Path) -> Result<TempDir> {
-    let tempdir = tempdir()?;
-
-    write(tempdir.path().join("Cargo.toml"), CARGO_TOML)?;
-    copy(
-        build_script_path,
-        tempdir.path().join("custom_build_name.rs"),
-    )?;
-    create_dir(tempdir.path().join("src"))?;
-    write(tempdir.path().join("src/lib.rs"), "")?;
-
-    Ok(tempdir)
-}
-
-const CARGO_TOML: &str = r#"
-[package]
-name = "temp-package"
-version = "0.1.0"
-edition = "2021"
-publish = false
-
-build = "custom_build_name.rs"
-"#;