test only relevant packages for subnet-evm (#4345)

Signed-off-by: Ceyhun Onur <[email protected]>

Author: ceyonur

tests/imports_test.go

@@ -12,16 +12,25 @@ import (
 	"github.com/ava-labs/avalanchego/utils/packages"
 )
 
+// TestMustNotImport tests that we do not import certain packages (like coreth's customtypes package) that would configure libevm globals.
+// Libevm panics if a package tries to register a custom type or extra after the globals have been configured (re-registration).
+// E2E test packages are used both from Subnet-EVM and Coreth.
+// Registering the libevm globals here in these packages does not necessarily break avalanchego e2e testing, but Subnet-EVM (or Coreth) E2E testing.
+// So any illegal use here will only be a problem once Subnet-EVM or Coreth bumps the avalanchego version, breaking the release cycles of
+// AvalancheGo and other repositories.
+// Transitory imports are also checked with packages.GetDependencies.
 func TestMustNotImport(t *testing.T) {
 	require := require.New(t)
 
+	// These packages configure libevm globally by registering custom types and extras.
+	illegalPaths := []string{
+		"github.com/ava-labs/coreth/params",
+		"github.com/ava-labs/coreth/plugin/evm/customtypes",
+	}
 	mustNotImport := map[string][]string{
-		// Importing these packages configures libevm globally. This must not be
-		// done to support both coreth and subnet-evm.
-		"tests/...": {
-			"github.com/ava-labs/coreth/params",
-			"github.com/ava-labs/coreth/plugin/evm/customtypes",
-		},
+		"tests/":            illegalPaths,
+		"tests/antithesis/": illegalPaths,
+		"tests/fixture/...": illegalPaths,
 	}
 	for packageName, forbiddenImports := range mustNotImport {
 		packagePath := path.Join("github.com/ava-labs/avalanchego", packageName)