1 files changed, 177 insertions, 0 deletions
diff --git a/tester/tester.go b/tester/tester.go
new file mode 100644
index 0000000..ef3ca61
--- /dev/null
+++ b/tester/tester.go
@@ -0,0 +1,177 @@
+package tester
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+	"path/filepath"
+	"runtime/debug"
+	"strings"
+
+	"github.com/nihei9/vartan/driver"
+	gspec "github.com/nihei9/vartan/spec/grammar"
+	tspec "github.com/nihei9/vartan/spec/test"
+)
+
+type TestResult struct {
+	TestCasePath string
+	Error        error
+	Diffs        []*tspec.TreeDiff
+}
+
+func (r *TestResult) String() string {
+	if r.Error != nil {
+		const indent1 = "    "
+		const indent2 = indent1 + indent1
+
+		msgLines := strings.Split(r.Error.Error(), "\n")
+		msg := fmt.Sprintf("Failed %v:\n%v%v", r.TestCasePath, indent1, strings.Join(msgLines, "\n"+indent1))
+		if len(r.Diffs) == 0 {
+			return msg
+		}
+		var diffLines []string
+		for _, diff := range r.Diffs {
+			diffLines = append(diffLines, diff.Message)
+			diffLines = append(diffLines, fmt.Sprintf("%vexpected path: %v", indent1, diff.ExpectedPath))
+			diffLines = append(diffLines, fmt.Sprintf("%vactual path:   %v", indent1, diff.ActualPath))
+		}
+		return fmt.Sprintf("%v\n%v%v", msg, indent2, strings.Join(diffLines, "\n"+indent2))
+	}
+	return fmt.Sprintf("Passed %v", r.TestCasePath)
+}
+
+type TestCaseWithMetadata struct {
+	TestCase *tspec.TestCase
+	FilePath string
+	Error    error
+}
+
+func ListTestCases(testPath string) []*TestCaseWithMetadata {
+	fi, err := os.Stat(testPath)
+	if err != nil {
+		return []*TestCaseWithMetadata{
+			{
+				FilePath: testPath,
+				Error:    err,
+			},
+		}
+	}
+	if !fi.IsDir() {
+		c, err := parseTestCase(testPath)
+		return []*TestCaseWithMetadata{
+			{
+				TestCase: c,
+				FilePath: testPath,
+				Error:    err,
+			},
+		}
+	}
+
+	es, err := os.ReadDir(testPath)
+	if err != nil {
+		return []*TestCaseWithMetadata{
+			{
+				FilePath: testPath,
+				Error:    err,
+			},
+		}
+	}
+	var cases []*TestCaseWithMetadata
+	for _, e := range es {
+		cs := ListTestCases(filepath.Join(testPath, e.Name()))
+		cases = append(cases, cs...)
+	}
+	return cases
+}
+
+func parseTestCase(testCasePath string) (*tspec.TestCase, error) {
+	f, err := os.Open(testCasePath)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	return tspec.ParseTestCase(f)
+}
+
+type Tester struct {
+	Grammar *gspec.CompiledGrammar
+	Cases   []*TestCaseWithMetadata
+}
+
+func (t *Tester) Run() []*TestResult {
+	var rs []*TestResult
+	for _, c := range t.Cases {
+		rs = append(rs, runTest(t.Grammar, c))
+	}
+	return rs
+}
+
+func runTest(g *gspec.CompiledGrammar, c *TestCaseWithMetadata) *TestResult {
+	var p *driver.Parser
+	var tb *driver.DefaulSyntaxTreeBuilder
+	{
+		gram := driver.NewGrammar(g)
+		toks, err := driver.NewTokenStream(g, bytes.NewReader(c.TestCase.Source))
+		if err != nil {
+			return &TestResult{
+				TestCasePath: c.FilePath,
+				Error:        err,
+			}
+		}
+		tb = driver.NewDefaultSyntaxTreeBuilder()
+		p, err = driver.NewParser(toks, gram, driver.SemanticAction(driver.NewASTActionSet(gram, tb)))
+		if err != nil {
+			return &TestResult{
+				TestCasePath: c.FilePath,
+				Error:        err,
+			}
+		}
+	}
+
+	err := p.Parse()
+	if err != nil {
+		return &TestResult{
+			TestCasePath: c.FilePath,
+			Error:        err,
+		}
+	}
+
+	if tb.Tree() == nil {
+		var err error
+		if len(p.SyntaxErrors()) > 0 {
+			err = fmt.Errorf("parse tree was not generated: syntax error occurred")
+		} else {
+			// The parser should always generate a parse tree in the vartan-test command, so if there is no parse
+			// tree, it is a bug. We also include a stack trace in the error message to be sure.
+			err = fmt.Errorf("parse tree was not generated: no syntax error:\n%v", string(debug.Stack()))
+		}
+		return &TestResult{
+			TestCasePath: c.FilePath,
+			Error:        err,
+		}
+	}
+
+	// When a parse tree exists, the test continues regardless of whether or not syntax errors occurred.
+	diffs := tspec.DiffTree(genTree(tb.Tree()).Fill(), c.TestCase.Output)
+	if len(diffs) > 0 {
+		return &TestResult{
+			TestCasePath: c.FilePath,
+			Error:        fmt.Errorf("output mismatch"),
+			Diffs:        diffs,
+		}
+	}
+	return &TestResult{
+		TestCasePath: c.FilePath,
+	}
+}
+
+func genTree(dTree *driver.Node) *tspec.Tree {
+	var children []*tspec.Tree
+	if len(dTree.Children) > 0 {
+		children = make([]*tspec.Tree, len(dTree.Children))
+		for i, c := range dTree.Children {
+			children[i] = genTree(c)
+		}
+	}
+	return tspec.NewTree(dTree.KindName, children...)
+}