test: parse testcases with gotemplate

this ensures all testcases obey the gotemplate grammar
and we are compatible with the official implementation

test/corpus_test.go

@@ -0,0 +1,122 @@
+package test
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+	"testing"
+	"text/template"
+)
+
+var (
+	TESTCASE_SEPERATOR     = regexp.MustCompile("\n(=+)\n")
+	INPUT_OUTPUT_SEPERATOR = regexp.MustCompile("\n(---)\n")
+	TESTS_DIR              = "./corpus"
+)
+
+func TestCorpus(t *testing.T) {
+	testCases, err := getTestCases()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	fmt.Printf("Got %d test cases\n", len(testCases))
+
+	for _, testCase := range testCases {
+		t.Run(testCase.name, func(t *testing.T) {
+			testTemplate(t, testCase.input, testCase.isError)
+		})
+	}
+}
+
+func testTemplate(t *testing.T, input string, isError bool) {
+	t.Helper()
+
+	input = fmt.Sprintf("{{ $var := 1}} \n %s", input)
+	_, err := template.New("template").Funcs(
+		template.FuncMap{
+			"pipeline":     func() string { return "" },
+			"functionName": func() string { return "" },
+			"condition":    func() string { return "" },
+		},
+	).Parse(input)
+
+	if err != nil && !isError {
+		t.Fatal(err)
+	} else if err == nil && isError {
+		t.Fatal("expected error")
+	}
+}
+
+type TestCase struct {
+	file        string
+	name        string
+	input       string
+	sExpression string
+	isError     bool
+}
+
+func NewTestCase(file, name, input, sExpression string) TestCase {
+	return TestCase{
+		name:        fmt.Sprintf("%s: %s", file, name),
+		input:       input,
+		sExpression: sExpression,
+		isError:     strings.Contains(sExpression, "(ERROR"),
+	}
+}
+
+func getTestCasesForFile(filename string, content string) []TestCase {
+	testCases := []TestCase{}
+	parts := TESTCASE_SEPERATOR.Split(content, -1)
+
+	for i := 0; i < len(parts); i++ {
+		if i%2 == 0 && len(parts) > i+1 {
+
+			testName := strings.TrimSpace(parts[i])
+			testContent := parts[i+1]
+			testParts := INPUT_OUTPUT_SEPERATOR.Split(testContent, -1)
+
+			if len(testParts) != 2 {
+				continue
+			}
+
+			testCases = append(testCases,
+				NewTestCase(
+					filename,
+					testName,
+					testParts[0],
+					testParts[1],
+				),
+			)
+		}
+	}
+
+	return testCases
+}
+
+func getTestCases() ([]TestCase, error) {
+	var testCases []TestCase
+
+	err := filepath.Walk(TESTS_DIR, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if !info.IsDir() && strings.HasSuffix(info.Name(), ".txt") {
+			content, err := os.ReadFile(path)
+			if err != nil {
+				return err
+			}
+
+			testCases = append(testCases, getTestCasesForFile(path, string(content))...)
+		}
+		return nil
+	})
+	if err != nil {
+		fmt.Println("Error walking the path:", err)
+		return nil, err
+	}
+
+	return testCases, nil
+}

test/go.mod

@@ -0,0 +1,3 @@
+module github.com/ngalaiko/tree-sitter-go-template/test
+
+go 1.23.4