Add tests for go1.21 and fix issues building on go1.21 (#137)

* Move gin tests to go1.21

* Create archive directories if needed

* Extract go.env from archive tarball

* Remove unneeded code

* Add a changelog entry around installing go.env

* Update fixture package name

CHANGELOG.md

@@ -7,7 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+- Ensure $GOROOT/go.env is installed.
 - Added go1.21.0.
+
 ## [0.1.7] - 2023-08-07
 
 - Added go1.19.12, go1.20.7, go1.21rc4.
@@ -52,4 +54,4 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 [0.1.3]: https://github.com/heroku/buildpacks-go/compare/v0.1.2...v0.1.3
 [0.1.2]: https://github.com/heroku/buildpacks-go/compare/v0.1.1...v0.1.2
 [0.1.1]: https://github.com/heroku/buildpacks-go/compare/v0.1.0...v0.1.1
-[0.1.0]: https://github.com/heroku/buildpacks-go/releases/tag/v0.1.0
+[0.1.0]: https://github.com/heroku/buildpacks-go/releases/tag/v0.1.0

src/layers/dist.rs

@@ -49,7 +49,7 @@ impl Layer for DistLayer {
         tgz::fetch_strip_filter_extract_verify(
             self.artifact.mirror_tarball_url(),
             "go",
-            ["bin", "src", "pkg", "LICENSE"].into_iter(),
+            ["bin", "src", "pkg", "go.env", "LICENSE"].into_iter(),
             layer_path,
             &self.artifact.sha_checksum,
         )

src/tgz.rs

@@ -3,7 +3,7 @@ use sha2::{
     digest::{generic_array::GenericArray, OutputSizeUser},
     Digest, Sha256,
 };
-use std::{io::Read, path::StripPrefixError};
+use std::{fs, io::Read, path::StripPrefixError};
 use tar::Archive;
 
 #[derive(thiserror::Error, Debug)]
@@ -23,6 +23,9 @@ pub(crate) enum Error {
     #[error("Failed to validate archive checksum; expected {0}, but found {1}")]
     Checksum(String, String),
 
+    #[error("Error creating archive directory: {0}")]
+    Directory(std::io::Error),
+
     #[error("Error writing archive entry: {0}")]
     Unpack(std::io::Error),
 
@@ -65,6 +68,9 @@ pub(crate) fn fetch_strip_filter_extract_verify<'a>(
             .iter()
             .any(|prefix| path.starts_with(destination.join(prefix)))
         {
+            if let Some(parent) = path.parent() {
+                fs::create_dir_all(parent).map_err(Error::Directory)?;
+            }
             file.unpack(&path).map_err(Error::Unpack)?;
         }
     }

tests/fixtures/modules_gin_118/go.mod → tests/fixtures/modules_gin_121/go.mod

@@ -1,6 +1,6 @@
-module example.com/modules_gin_118
+module example.com/modules_gin_121
 
-go 1.18
+go 1.21
 
 require github.com/gin-gonic/gin v1.8.1
 

tests/fixtures/modules_gin_118/main.go → tests/fixtures/modules_gin_121/main.go

@@ -7,7 +7,7 @@ import (
 func main() {
 	r := gin.Default()
 	r.GET("/", func(c *gin.Context) {
-		c.String(200, "modules_gin_118")
+		c.String(200, "modules_gin_121")
 	})
 	r.Run()
 }

tests/integration_test.rs

@@ -83,27 +83,27 @@ fn vendor_gorilla_117_22() {
     test_vendor_gorilla_117("heroku/builder:22");
 }
 
-fn test_modules_gin_118(builder: &str) {
+fn test_modules_gin_121(builder: &str) {
     test_go_fixture(
-        "modules_gin_118",
+        "modules_gin_121",
         builder,
         &[
-            "Detected Go version requirement: =1.18",
-            "Installing Go 1.18",
+            "Detected Go version requirement: =1.21",
+            "Installing Go 1.21",
             "downloading github.com/gin-gonic/gin v1.8.1",
         ],
         &[],
     );
 }
 #[test]
 #[ignore = "integration test"]
-fn modules_gin_118_20() {
-    test_modules_gin_118("heroku/buildpacks:20");
+fn modules_gin_121_20() {
+    test_modules_gin_121("heroku/buildpacks:20");
 }
 #[test]
 #[ignore = "integration test"]
-fn modules_gin_118_22() {
-    test_modules_gin_118("heroku/builder:22");
+fn modules_gin_121_22() {
+    test_modules_gin_121("heroku/builder:22");
 }
 
 fn test_worker_http_118(builder: &str) {