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package eval_test
import (
"bytes"
"fmt"
"os"
"os/exec"
"path/filepath"
"runtime"
"strings"
"sync"
"sync/atomic"
"testing"
"github.com/nixos/lix/gonix/eval"
)
// ---------------------------------------------------------------------------
// Unit tests: ParseNixJSON round-trip
// ---------------------------------------------------------------------------
func TestParseNixJSON_Literal(t *testing.T) {
json := `{"_type":"ExprLiteral","value":42,"valueType":"Int"}`
n, err := eval.ParseNixJSON([]byte(json))
if err != nil {
t.Fatal(err)
}
if n.Type != "ExprLiteral" || n.LitValueType != "Int" || n.LitValue != int64(42) {
t.Errorf("got %+v", n)
}
}
func TestParseNixJSON_Var(t *testing.T) {
json := `{"_type":"ExprVar","value":"foo"}`
n, err := eval.ParseNixJSON([]byte(json))
if err != nil {
t.Fatal(err)
}
if n.Type != "ExprVar" || n.VarName != "foo" {
t.Errorf("got %+v", n)
}
}
func TestParseNixJSON_Lambda(t *testing.T) {
json := `{
"_type": "ExprLambda",
"arg": "x",
"body": {"_type":"ExprVar","value":"x"},
"formals": {"a": null, "b": {"_type":"ExprLiteral","value":1,"valueType":"Int"}},
"formalsEllipsis": true
}`
n, err := eval.ParseNixJSON([]byte(json))
if err != nil {
t.Fatal(err)
}
if n.LambdaArg != "x" {
t.Errorf("arg = %q", n.LambdaArg)
}
if !n.LambdaEllipsis {
t.Error("expected ellipsis")
}
if n.LambdaFormals["a"] != nil {
t.Error("formal a should have nil default")
}
if n.LambdaFormals["b"] == nil || n.LambdaFormals["b"].LitValue != int64(1) {
t.Error("formal b should have default 1")
}
}
// ---------------------------------------------------------------------------
// Unit tests: ExprToNode
// ---------------------------------------------------------------------------
func TestExprToNode_IntLiteral(t *testing.T) {
symbols := eval.NewSymbolTable()
expr := eval.NewExprInt(eval.PosIdx(0), 42)
n := eval.ExprToNode(expr, symbols)
if n.Type != "ExprLiteral" || n.LitValueType != "Int" || n.LitValue != int64(42) {
t.Errorf("got %+v", n)
}
}
func TestExprToNode_Var(t *testing.T) {
symbols := eval.NewSymbolTable()
sym := symbols.Create("foo")
expr := &eval.ExprVar{Name: sym}
n := eval.ExprToNode(expr, symbols)
if n.Type != "ExprVar" || n.VarName != "foo" {
t.Errorf("got %+v", n)
}
}
// ---------------------------------------------------------------------------
// Integration: compare Go parser against nix-instantiate --parse
// ---------------------------------------------------------------------------
// nixInstantiateParse runs `nix-instantiate --parse <file>` and returns the
// JSON output. Returns an error if the command fails.
func nixInstantiateParse(filePath string) ([]byte, error) {
cmd := exec.Command("nix-instantiate", "--parse", filePath)
var stdout, stderr bytes.Buffer
cmd.Stdout = &stdout
cmd.Stderr = &stderr
if err := cmd.Run(); err != nil {
return nil, fmt.Errorf("%v: %s", err, stderr.String())
}
return stdout.Bytes(), nil
}
// compareFileAST parses a .nix file with both nix-instantiate and our Go parser,
// then compares the resulting ASTs.
func compareFileAST(t *testing.T, filePath string, symbols *eval.SymbolTable, builtinNames []string) []eval.Diff {
t.Helper()
// Get nix-instantiate --parse output
nixJSON, err := nixInstantiateParse(filePath)
if err != nil {
t.Fatalf("nix-instantiate --parse %s: %v", filePath, err)
}
nixNode, err := eval.ParseNixJSON(nixJSON)
if err != nil {
t.Fatalf("ParseNixJSON for %s: %v", filePath, err)
}
// Parse with Go native parser
src, err := os.ReadFile(filePath)
if err != nil {
t.Fatalf("read %s: %v", filePath, err)
}
basePath := filepath.Dir(filePath) + "/"
goExpr, err := eval.NativeParseExpr(src, basePath, filePath, symbols, builtinNames)
if err != nil {
t.Fatalf("NativeParseExpr %s: %v", filePath, err)
}
goNode := eval.ExprToNode(goExpr, symbols)
return eval.CompareAST(nixNode, goNode)
}
// TestASTCompare_SimpleExprs tests the comparison on inline expressions.
// We write them to temp files so nix-instantiate can parse them.
func TestASTCompare_SimpleExprs(t *testing.T) {
if _, err := exec.LookPath("nix-instantiate"); err != nil {
t.Skip("nix-instantiate not in PATH")
}
requireWasm(t)
exprs := []struct {
name string
src string
}{
{"int", "42"},
{"float", "3.14"},
{"string", `"hello world"`},
{"true", "a: true"},
{"null", "a: null"},
{"lambda_simple", "x: x"},
{"lambda_formals", "{ a, b ? 1, ...}@args: a"},
{"lambda_formals_no_at", "{ a, b }: a"},
{"call", "a: b: a b"},
{"call_multi", "f: a: b: f a b"},
{"attrset", "{ a = 1; b = 2; }"},
{"attrset_rec", "rec { a = 1; b = a; }"},
{"attrset_nested", "{ a.b = 1; a.c = 2; }"},
{"let", "let a = 1; in a"},
{"let_inherit", "a: let inherit a; b = 1; in b"},
{"with", "x: with x; x"},
{"if", "a: if a then 1 else 2"},
{"assert", "a: assert a; a"},
{"list", "[ 1 2 3 ]"},
{"select", "a: a.b"},
{"select_or", "a: a.b or 1"},
{"has_attr", "a: a ? b"},
{"not", "a: !a"},
{"eq", "a: b: a == b"},
{"neq", "a: b: a != b"},
{"and", "a: b: a && b"},
{"or", "a: b: a || b"},
{"impl", "a: b: a -> b"},
{"update", "a: b: a // b"},
{"concat_lists", "a: b: a ++ b"},
{"add", "a: b: a + b"},
{"sub", "a: b: a - b"},
{"mul", "a: b: a * b"},
{"div", "a: b: a / b"},
{"lt", "a: b: a < b"},
{"gt", "a: b: a > b"},
{"le", "a: b: a <= b"},
{"ge", "a: b: a >= b"},
{"negate", "a: -a"},
{"concat_strings", `a: "hello ${a} world"`},
{"inherit_from", "a: { inherit (a) b c; }"},
{"search_path", "a: <nixpkgs>"},
{"cur_pos", "a: __curPos"},
{"indented_string", "a: ''\n hello ${a}\n world\n''"},
{"path_absolute", "a: /foo/bar"},
{"dynamic_attr_select", "a: b: a.${b}"},
{"mixed_inherit", "a: b: { inherit a; inherit (b) c; d = 1; }"},
}
for _, tc := range exprs {
t.Run(tc.name, func(t *testing.T) {
// Write to temp file
tmpFile := filepath.Join(t.TempDir(), "in.nix")
if err := os.WriteFile(tmpFile, []byte(tc.src), 0644); err != nil {
t.Fatal(err)
}
symbols := eval.NewSymbolTable()
diffs := compareFileAST(t, tmpFile, symbols, testBuiltinNames)
if len(diffs) > 0 {
t.Errorf("AST diff for %q:\n%s", tc.src, eval.FormatDiffs(diffs))
}
})
}
}
// ---------------------------------------------------------------------------
// Mass comparison: all .nix files in a directory tree
// ---------------------------------------------------------------------------
// TestASTCompare_Nixpkgs runs the AST comparison against every .nix file in
// the directory specified by the NIXPKGS_PATH environment variable.
//
// Usage:
//
// NIXPKGS_PATH=~/nixpkgs go test ./eval -run TestASTCompare_Nixpkgs -count=1 -timeout=30m
func TestASTCompare_Nixpkgs(t *testing.T) {
nixpkgsPath := os.Getenv("NIXPKGS_PATH")
if nixpkgsPath == "" {
t.Skip("NIXPKGS_PATH not set; skipping nixpkgs AST comparison")
}
if _, err := exec.LookPath("nix-instantiate"); err != nil {
t.Skip("nix-instantiate not in PATH")
}
requireWasm(t)
// Collect all .nix files
var files []string
err := filepath.Walk(nixpkgsPath, func(path string, info os.FileInfo, err error) error {
if err != nil {
return nil // skip unreadable dirs
}
// Skip .git and other hidden directories
if info.IsDir() && strings.HasPrefix(info.Name(), ".") {
return filepath.SkipDir
}
if !info.IsDir() && strings.HasSuffix(path, ".nix") {
files = append(files, path)
}
return nil
})
if err != nil {
t.Fatalf("walking %s: %v", nixpkgsPath, err)
}
t.Logf("found %d .nix files in %s", len(files), nixpkgsPath)
// Determine parallelism
numWorkers := runtime.NumCPU()
if numWorkers > 16 {
numWorkers = 16
}
var (
total atomic.Int64
passed atomic.Int64
nixFailed atomic.Int64 // nix-instantiate --parse failed
goFailed atomic.Int64 // Go parser failed
bothFailed atomic.Int64 // both failed (expected — e.g. syntax errors)
diffCount atomic.Int64 // AST mismatch
mu sync.Mutex
diffFiles []string // files with AST differences (collect first N)
)
const maxDiffReport = 50
// Work queue
fileCh := make(chan string, numWorkers*2)
var wg sync.WaitGroup
for i := 0; i < numWorkers; i++ {
wg.Add(1)
go func() {
defer wg.Done()
// Each worker gets its own SymbolTable to avoid contention
symbols := eval.NewSymbolTable()
for filePath := range fileCh {
total.Add(1)
// Run nix-instantiate --parse
nixJSON, nixErr := nixInstantiateParse(filePath)
// Run Go native parser
src, readErr := os.ReadFile(filePath)
if readErr != nil {
continue
}
basePath := filepath.Dir(filePath) + "/"
goExpr, goErr := eval.NativeParseExpr(src, basePath, filePath, symbols, testBuiltinNames)
if nixErr != nil && goErr != nil {
// Both failed — expected for malformed files
bothFailed.Add(1)
continue
}
if nixErr != nil {
// nix-instantiate failed but Go succeeded — nix rejects but we accept
nixFailed.Add(1)
continue
}
if goErr != nil {
// Go parser failed but nix-instantiate succeeded — parser bug
goFailed.Add(1)
mu.Lock()
if len(diffFiles) < maxDiffReport {
diffFiles = append(diffFiles, fmt.Sprintf("GO_PARSE_FAIL: %s: %v", filePath, goErr))
}
mu.Unlock()
continue
}
// Both succeeded — compare ASTs
nixNode, err := eval.ParseNixJSON(nixJSON)
if err != nil {
mu.Lock()
if len(diffFiles) < maxDiffReport {
diffFiles = append(diffFiles, fmt.Sprintf("JSON_PARSE_FAIL: %s: %v", filePath, err))
}
mu.Unlock()
continue
}
goNode := eval.ExprToNode(goExpr, symbols)
diffs := eval.CompareAST(nixNode, goNode)
if len(diffs) > 0 {
diffCount.Add(1)
mu.Lock()
if len(diffFiles) < maxDiffReport {
// Show first diff only for brevity
diffFiles = append(diffFiles, fmt.Sprintf("DIFF: %s: %s", filePath, diffs[0].String()))
}
mu.Unlock()
} else {
passed.Add(1)
}
}
}()
}
// Feed files to workers
for _, f := range files {
fileCh <- f
}
close(fileCh)
wg.Wait()
// Report
t.Logf("Results:")
t.Logf(" total: %d", total.Load())
t.Logf(" passed: %d", passed.Load())
t.Logf(" both failed: %d (expected)", bothFailed.Load())
t.Logf(" nix rejected: %d (nix failed, go succeeded)", nixFailed.Load())
t.Logf(" go failed: %d (go failed, nix succeeded)", goFailed.Load())
t.Logf(" AST diff: %d", diffCount.Load())
if len(diffFiles) > 0 {
t.Logf("\nFirst %d issues:", len(diffFiles))
for _, s := range diffFiles {
t.Logf(" %s", s)
}
}
goFailedN := goFailed.Load()
diffN := diffCount.Load()
if goFailedN > 0 || diffN > 0 {
t.Errorf("%d parse failures + %d AST mismatches (see above)", goFailedN, diffN)
}
}
|