check the default user cachedir if GOCACHE is not explicitly set

tools/osutils/cmd.go

@@ -63,17 +63,3 @@ func YesNoPrompt(message string, fallback bool) bool {
 		}
 	}
 }
-
-// IsProbablyGoRun loosely checks if the current executable is running
-// as a result of "go run".
-func IsProbablyGoRun() bool {
-	runDirs := []string{os.TempDir(), os.Getenv("GOCACHE")}
-
-	for _, dir := range runDirs {
-		if dir != "" && strings.HasPrefix(os.Args[0], dir) {
-			return true
-		}
-	}
-
-	return false
-}

tools/osutils/cmd_test.go

@@ -64,40 +64,3 @@ func TestYesNoPrompt(t *testing.T) {
 		})
 	}
 }
-
-func TestIsProbablyGoRun(t *testing.T) {
-	scenarios := []struct {
-		arg      string
-		envs     map[string]string
-		expected bool
-	}{
-		{"", nil, false},
-		{"a/b/c", nil, false},
-		{"/a/b/c", nil, false},
-		{"/a/b/c", map[string]string{"GOCACHE": "/b/"}, false},
-		{"/a/b/c", map[string]string{"GOCACHE": "/a/"}, true},
-		{os.TempDir() + "/a/b/c", nil, true},
-	}
-
-	originalArgs := os.Args
-	defer func() {
-		os.Args = originalArgs
-	}()
-
-	for _, s := range scenarios {
-		t.Run(s.arg, func(t *testing.T) {
-			os.Args = []string{s.arg}
-
-			for k, v := range s.envs {
-				defer os.Setenv(k, os.Getenv(k))
-				os.Setenv(k, v)
-			}
-
-			result := osutils.IsProbablyGoRun()
-
-			if result != s.expected {
-				t.Fatalf("Expected %v, got %v", s.expected, result)
-			}
-		})
-	}
-}

tools/osutils/run.go

@@ -0,0 +1,33 @@
+package osutils
+
+import (
+	"os"
+	"strings"
+)
+
+var runDirs = []string{os.TempDir(), cacheDir()}
+
+// IsProbablyGoRun loosely checks if the current executable is running
+// as a result of "go run".
+func IsProbablyGoRun() bool {
+	for _, dir := range runDirs {
+		if dir != "" && strings.HasPrefix(os.Args[0], dir) {
+			return true
+		}
+	}
+
+	return false
+}
+
+func cacheDir() string {
+	dir := os.Getenv("GOCACHE")
+	if dir == "off" {
+		return ""
+	}
+
+	if dir == "" {
+		dir, _ = os.UserCacheDir()
+	}
+
+	return dir
+}

tools/osutils/run_test.go

@@ -0,0 +1,45 @@
+package osutils
+
+import (
+	"os"
+	"strconv"
+	"testing"
+)
+
+func TestIsProbablyGoRun(t *testing.T) {
+	scenarios := []struct {
+		arg0     string
+		runDirs  []string
+		expected bool
+	}{
+		{"", nil, false},
+		{"/a/b", nil, false},
+		{"/a/b", []string{""}, false},
+		{"/a/b", []string{"/b/"}, false},
+		{"/a/b", []string{"/a/"}, true},
+		{"/a/b", []string{"", "/b/", "/a/"}, true},
+	}
+
+	originalArgs := os.Args
+	defer func() {
+		os.Args = originalArgs
+	}()
+
+	originalRunDirs := runDirs
+	defer func() {
+		runDirs = originalRunDirs
+	}()
+
+	for i, s := range scenarios {
+		t.Run(strconv.Itoa(i)+"_"+s.arg0, func(t *testing.T) {
+			os.Args = []string{s.arg0}
+			runDirs = s.runDirs
+
+			result := IsProbablyGoRun()
+
+			if result != s.expected {
+				t.Fatalf("Expected %v, got %v", s.expected, result)
+			}
+		})
+	}
+}