test: add import compliance tests

vms/evm/imports_test.go

@@ -0,0 +1,168 @@
+// Copyright (C) 2019-2025, Ava Labs, Inc. All rights reserved.
+// See the file LICENSE for licensing terms.
+
+package tests
+
+import (
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"os"
+	"path/filepath"
+	"regexp"
+	"slices"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/ava-labs/avalanchego/utils/set"
+)
+
+// TestDoNotImportFromGraft ensures proper import rules for graft packages:
+// - graft/coreth can be imported anywhere EXCEPT vms/evm (but vms/evm/emulate is an exception)
+// - graft/subnet-evm cannot be imported anywhere EXCEPT vms/evm/emulate
+func TestEnforceGraftImportBoundaries(t *testing.T) {
+	graftRegex := regexp.MustCompile(`^github\.com/ava-labs/avalanchego/graft(/|$)`)
+
+	// Find all graft imports in the entire repository
+	foundImports, err := findImportsMatchingPattern("..", graftRegex, func(path string, importPath string, _ *ast.ImportSpec) bool {
+		// Skip generated files and test-specific files
+		filename := filepath.Base(path)
+		if strings.HasPrefix(filename, "gen_") ||
+			strings.Contains(path, "graft/*/core/main_test.go") ||
+			strings.Contains(path, "graft/*/tempextrastest/") {
+			return true
+		}
+
+		// Skip files in the graft directory itself - they can import from graft
+		if strings.Contains(path, "/graft/") {
+			return true
+		}
+
+		isInEmulate := strings.Contains(path, "/vms/evm/emulate/")
+		isInVmsEvm := strings.Contains(path, "/vms/evm/")
+		isCoreth := strings.Contains(importPath, "/graft/coreth")
+		isSubnetEVM := strings.Contains(importPath, "/graft/subnet-evm")
+
+		// graft/coreth: illegal in vms/evm except vms/evm/emulate
+		if isCoreth && isInVmsEvm && !isInEmulate {
+			return false
+		}
+
+		// graft/subnet-evm: illegal everywhere except vms/evm/emulate
+		if isSubnetEVM && !isInEmulate {
+			return false
+		}
+
+		return true
+	})
+	require.NoError(t, err, "Failed to find graft imports")
+
+	if len(foundImports) == 0 {
+		return // no violations found
+	}
+
+	header := "Graft import rules violated!\n" +
+		"Rules:\n" +
+		"  - graft/coreth can be imported anywhere EXCEPT vms/evm (but vms/evm/emulate is an exception)\n" +
+		"  - graft/subnet-evm cannot be imported anywhere EXCEPT vms/evm/emulate\n\n"
+	require.Fail(t, formatImportViolations(foundImports, header))
+}
+
+// TestDoNotImportLibevmPseudo ensures that no code in the repository imports
+// the libevm/pseudo package, which is for internal libevm use only.
+func TestDoNotImportLibevmPseudo(t *testing.T) {
+	// Find imports from the forbidden libevm/pseudo package
+	pseudoRegex := regexp.MustCompile(`^github\.com/ava-labs/libevm/libevm/pseudo`)
+	foundImports, err := findImportsMatchingPattern("../..", pseudoRegex, nil)
+	require.NoError(t, err, "Failed to scan for libevm/pseudo imports")
+
+	if len(foundImports) == 0 {
+		return // no violations found
+	}
+
+	header := "Files must not import libevm/pseudo!\n" +
+		"The pseudo package is for internal libevm use only.\n\n"
+	require.Fail(t, formatImportViolations(foundImports, header))
+}
+
+// formatImportViolations formats a map of import violations into an error message
+func formatImportViolations(violations map[string]set.Set[string], header string) string {
+	sortedViolations := make([]string, 0, len(violations))
+	for importPath := range violations {
+		sortedViolations = append(sortedViolations, importPath)
+	}
+	slices.Sort(sortedViolations)
+
+	var errorMsg strings.Builder
+	errorMsg.WriteString(header)
+	errorMsg.WriteString("Violations:\n\n")
+
+	for _, importPath := range sortedViolations {
+		files := violations[importPath]
+		fileList := files.List()
+		slices.Sort(fileList)
+
+		errorMsg.WriteString(fmt.Sprintf("- %s\n", importPath))
+		errorMsg.WriteString(fmt.Sprintf("   Used in %d file(s):\n", len(fileList)))
+		for _, file := range fileList {
+			errorMsg.WriteString(fmt.Sprintf("   • %s\n", file))
+		}
+		errorMsg.WriteString("\n")
+	}
+
+	return errorMsg.String()
+}
+
+// findImportsMatchingPattern is a generalized function that finds all imports
+// matching a given regex pattern in the specified directory.
+// The filterFunc can be used to skip certain files or imports (return true to skip).
+// Returns a map of import paths to the set of files that contain them.
+func findImportsMatchingPattern(
+	rootDir string,
+	importRegex *regexp.Regexp,
+	filterFunc func(filePath string, importPath string, importSpec *ast.ImportSpec) bool,
+) (map[string]set.Set[string], error) {
+	imports := make(map[string]set.Set[string])
+
+	err := filepath.Walk(rootDir, func(path string, _ os.FileInfo, err error) error {
+		if err != nil || !strings.HasSuffix(path, ".go") {
+			return err
+		}
+
+		node, err := parser.ParseFile(token.NewFileSet(), path, nil, parser.ParseComments)
+		if err != nil {
+			return fmt.Errorf("failed to parse %s: %w", path, err)
+		}
+
+		for _, imp := range node.Imports {
+			if imp.Path == nil {
+				continue
+			}
+
+			importPath := strings.Trim(imp.Path.Value, `"`)
+			if !importRegex.MatchString(importPath) {
+				continue
+			}
+
+			if filterFunc != nil && filterFunc(path, importPath, imp) {
+				continue
+			}
+
+			if _, exists := imports[importPath]; !exists {
+				imports[importPath] = set.Set[string]{}
+			}
+			fileSet := imports[importPath]
+			fileSet.Add(path)
+			imports[importPath] = fileSet
+		}
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return imports, nil
+}