fix: prevent false positive recursion detection in tests (Fixes #564)

Problem: When building goenv AUR package with goenv-installed Go (not system Go), all exec tests fail with 'infinite recursion detected' error. This happens because _GOENV_EXEC_ACTIVE=1 is inherited from parent shell when tests run under goenv-managed Go.

Root Cause: Simple boolean check (if env var != '') creates false positive when tests inherit _GOENV_EXEC_ACTIVE from parent shell. Pattern: User has goenv Go active → runs 'paru -S goenv' → build runs 'make check' → 'go test' calls goenv exec internally → recursion guard finds inherited env var → FALSE POSITIVE.

Solution: Changed recursion guard from simple boolean check to PID-based detection. Now checks if env var value equals parent PID (os.Getppid()), indicating actual shim → exec → shim → exec recursion chain, not just inherited environment. Also added os.Unsetenv('_GOENV_EXEC_ACTIVE') in test setup as defensive measure.

Testing: All exec tests now pass (TestExecCommand with 9 subtests, TestExecEnvironmentVariables, TestExecWithShims). PID-based approach prevents false positives while still catching real infinite recursion.

Author: ChronosMasterOfAllTime

cmd/shims/exec.go

@@ -63,9 +63,13 @@ func runExec(cmd *cobra.Command, args []string) error {
 		args = args[1:]
 	}
 
-	// Recursion guard: detect if we're being called from a shim that we spawned
+	// Recursion guard: detect if we're being called from a shim that we spawned.
+	// We only treat this as recursion if the value equals our parent PID, indicating
+	// we were spawned by another goenv exec (shim → exec → shim → exec).
+	// This avoids false positives when running tests under goenv-managed Go.
 	const recursionEnvVar = "_GOENV_EXEC_ACTIVE"
-	if os.Getenv(recursionEnvVar) != "" {
+	parentPIDStr := fmt.Sprintf("%d", os.Getppid())
+	if os.Getenv(recursionEnvVar) == parentPIDStr {
 		return fmt.Errorf("goenv: infinite recursion detected — shim is calling goenv exec again. Run 'goenv rehash' to regenerate shims")
 	}
 
@@ -312,8 +316,9 @@ func runExec(cmd *cobra.Command, args []string) error {
 	}
 
 	// Execute with the modified environment
-	// Set recursion guard so shims don't re-enter goenv exec
-	execEnv = setEnvVar(execEnv, recursionEnvVar, "1")
+	// Set recursion guard so shims don't re-enter goenv exec.
+	// Use our PID as the value so the child can detect if it's being called recursively.
+	execEnv = setEnvVar(execEnv, recursionEnvVar, fmt.Sprintf("%d", os.Getpid()))
 	execCmd := exec.Command(commandPath, commandArgs...)
 	execCmd.Env = execEnv
 	execCmd.Stdin = os.Stdin

cmd/shims/exec_test.go

@@ -108,6 +108,10 @@ func TestExecCommand(t *testing.T) {
 			t.Setenv(utils.GoenvEnvVarVersion.String(), "")
 			os.Unsetenv("GOENV_VERSION")
 
+			// Clear _GOENV_EXEC_ACTIVE to avoid false recursion detection
+			// This can be set when tests are run via goenv-managed Go (e.g., during package builds)
+			os.Unsetenv("_GOENV_EXEC_ACTIVE")
+
 			// Setup test versions
 			for _, version := range tt.setupVersions {
 				cmdtest.CreateTestVersion(t, testRoot, version)