Use os.UserCacheDir as first fallback if cacheDir is not set

We will now try

1. cacheDir (or, commonly set in environment as `HUGO_CACHEDIR`)
2. if on Netlify we use `/opt/build/cache/hugo_cache/`
3. os.UserCacheDir
4. A temp dir

Storing the cache, especially the module cache, in a temporary idea has had lots of hard to debug issues, especially on MacOS,
which this commit tries to fix.

This should also make it easier to locate the Hugo cache:

>UserCacheDir returns the default root directory to use for user-specific cached data. Users should create their own
application-specific subdirectory within this one and use that.
>
>On Unix systems, it returns $XDG_CACHE_HOME as specified by
https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html if non-empty, else $HOME/.cache. On Darwin, it
returns $HOME/Library/Caches. On Windows, it returns %LocalAppData%. On Plan 9, it returns $home/lib/cache.
>
>If the location cannot be determined (for example, $HOME is not defined), then it will return an error.

Fixes #11286
Fixes #11291

1 files changed, 17 insertions, 2 deletions

diff --git a/main_test.go b/main_test.go
index 6274cd9bb..c5a59828f 100644
--- a/main_test.go
+++ b/main_test.go
@@ -375,8 +375,23 @@ func testSetupFunc() func(env *testscript.Env) error {
 	return func(env *testscript.Env) error {
 		var keyVals []string
 		keyVals = append(keyVals, "HUGO_TESTRUN", "true")
-		hugoCachedDir := filepath.Join(env.WorkDir, "hugocache")
-		keyVals = append(keyVals, "HUGO_CACHEDIR", hugoCachedDir)
+		keyVals = append(keyVals, "HUGO_CACHEDIR", filepath.Join(env.WorkDir, "hugocache"))
+		xdghome := filepath.Join(env.WorkDir, "xdgcachehome")
+		keyVals = append(keyVals, "XDG_CACHE_HOME", xdghome)
+		home := filepath.Join(env.WorkDir, "home")
+		keyVals = append(keyVals, "HOME", home)
+
+		if runtime.GOOS == "darwin" {
+			if err := os.MkdirAll(filepath.Join(home, "Library", "Caches"), 0777); err != nil {
+				return err
+			}
+		}
+
+		if runtime.GOOS == "linux" {
+			if err := os.MkdirAll(xdghome, 0777); err != nil {
+				return err
+			}
+		}
 
 		keyVals = append(keyVals, "SOURCE", sourceDir)