Add Prepare method for reusing state across linter runs (#1506)

This paves the way for moving initialization logic to Rego
later: #359

As well as moving the `DetermineEnabledRules` and
`DetermineEnabledAggregateRules` methods to instead use the
same query later on.

Fixes #1394

Signed-off-by: Anders Eknert <anders@styra.com>

Author: anderseknert

bundle/regal/rules/imports/circular-import/circular_import.rego

@@ -12,9 +12,8 @@ import data.regal.result
 import data.regal.util
 
 _refs contains ref if {
-	r := ast.found.refs[_][_]
-
-	r.value[0].value == "data"
+	some r
+	ast.found.refs[_][r].value[0].value == "data"
 
 	ast.static_ref(r)
 

cmd/fix.go

@@ -411,8 +411,7 @@ please run fix from a clean state to support the use of git to undo, or use --fo
 
 	if !params.dryRun {
 		for _, file := range fileProvider.DeletedFiles() {
-			err := os.Remove(file)
-			if err != nil {
+			if err := os.Remove(file); err != nil {
 				return fmt.Errorf("failed to delete file %s: %w", file, err)
 			}
 

cmd/lint.go

@@ -249,8 +249,7 @@ func lint(args []string, params *lintCommandParams) (report.Report, error) {
 		m.Timer(regalmetrics.RegalConfigSearch).Stop()
 	}
 
-	regal := linter.NewEmptyLinter().
-		WithAddedBundle(&rbundle.LoadedBundle).
+	regal := linter.NewLinter().
 		WithDisableAll(params.disableAll).
 		WithDisabledCategories(params.disableCategory.v...).
 		WithDisabledRules(params.disable.v...).
@@ -330,6 +329,11 @@ func lint(args []string, params *lintCommandParams) (report.Report, error) {
 
 	go updateCheckAndWarn(params, &rbundle.LoadedBundle, &userConfig)
 
+	regal, err = regal.Prepare(ctx)
+	if err != nil {
+		return report.Report{}, fmt.Errorf("failed to prepare for linting: %w", err)
+	}
+
 	result, err := regal.Lint(ctx)
 	if err != nil {
 		return report.Report{}, formatError(params.format, fmt.Errorf("error(s) encountered while linting: %w", err))

e2e/cli_test.go

@@ -22,6 +22,7 @@ import (
 
 	"github.com/open-policy-agent/opa/v1/tester"
 
+	"github.com/styrainc/regal/internal/mode"
 	"github.com/styrainc/regal/internal/testutil"
 	"github.com/styrainc/regal/pkg/config"
 	"github.com/styrainc/regal/pkg/report"
@@ -181,10 +182,11 @@ func TestLintNonExistentDir(t *testing.T) {
 	}
 }
 
-// NOTE(ae): this test *will fail* when run via "go test -e2e" and a normal development binary is used for the test.
-// This is because proposing fixes is only enabled when regal is built with the "regal_standalone" build tag. I spent
-// way more time on chasing that down than I would have wanted, so leaving this here for future me and others.
 func TestLintProposeToRunFix(t *testing.T) {
+	if !mode.Standalone {
+		t.Skip("test requires regal to be built with the 'regal_standalone' build tag")
+	}
+
 	t.Parallel()
 	stdout, stderr := bytes.Buffer{}, bytes.Buffer{}
 
@@ -1045,8 +1047,7 @@ allow := true
 func TestFixWithConflicts(t *testing.T) {
 	t.Parallel()
 
-	stdout := bytes.Buffer{}
-	stderr := bytes.Buffer{}
+	stdout, stderr := bytes.Buffer{}, bytes.Buffer{}
 
 	initialState := map[string]string{
 		".regal/config.yaml": "", // needed to find the root in the right place
@@ -1112,8 +1113,7 @@ Cannot move multiple files to: bar/bar.rego
 func TestFixWithConflictRenaming(t *testing.T) {
 	t.Parallel()
 
-	stdout := bytes.Buffer{}
-	stderr := bytes.Buffer{}
+	stdout, stderr := bytes.Buffer{}, bytes.Buffer{}
 
 	initialState := map[string]string{
 		".regal/config.yaml": "", // needed to find the root in the right place
@@ -1292,8 +1292,7 @@ rules:
 func TestLintAnnotationCustomAttributeMultipleItems(t *testing.T) {
 	t.Parallel()
 
-	stdout := bytes.Buffer{}
-	stderr := bytes.Buffer{}
+	stdout, stderr := bytes.Buffer{}, bytes.Buffer{}
 	cwd := testutil.Must(os.Getwd())(t)
 
 	err := regal(&stdout, &stderr)(

internal/io/io.go

@@ -17,6 +17,7 @@ import (
 	"github.com/open-policy-agent/opa/v1/loader/filter"
 	"github.com/open-policy-agent/opa/v1/rego"
 	"github.com/open-policy-agent/opa/v1/types"
+	outil "github.com/open-policy-agent/opa/v1/util"
 
 	"github.com/styrainc/roast/pkg/encoding"
 )
@@ -182,6 +183,55 @@ func FindManifestLocations(root string) ([]string, error) {
 	return foundBundleRoots, nil
 }
 
+func ModulesFromCustomRuleFS(customRuleFS files.FS, rootPath string) (map[string]*ast.Module, error) {
+	modules := make(map[string]*ast.Module)
+	filter := ExcludeTestFilter()
+
+	err := files.WalkDir(customRuleFS, rootPath, func(path string, d files.DirEntry, err error) error {
+		if err != nil {
+			return fmt.Errorf("failed to walk custom rule FS: %w", err)
+		}
+
+		if d.IsDir() {
+			return nil
+		}
+
+		info, err := d.Info()
+		if err != nil {
+			return fmt.Errorf("failed to get info for custom rule file: %w", err)
+		}
+
+		if filter("", info, 0) {
+			return nil
+		}
+
+		f, err := customRuleFS.Open(path)
+		if err != nil {
+			return fmt.Errorf("failed to open custom rule file: %w", err)
+		}
+		defer f.Close()
+
+		bs, err := io.ReadAll(f)
+		if err != nil {
+			return fmt.Errorf("failed to read custom rule file: %w", err)
+		}
+
+		m, err := ast.ParseModule(path, outil.ByteSliceToString(bs))
+		if err != nil {
+			return fmt.Errorf("failed to parse custom rule file %q: %w", path, err)
+		}
+
+		modules[path] = m
+
+		return nil
+	})
+	if err != nil {
+		return nil, fmt.Errorf("failed to walk custom rule FS: %w", err)
+	}
+
+	return modules, nil
+}
+
 // NOTE: These are mirrored here merely to provide correct capabilities for the
 // parser. Can't import other packages from here as almost all of them depend on
 // this package. We should probably move these definitions to somewhere where all