build basic test runner from package source and test files

* c2f6784 AST
* 9e4d962 Use x/tools/imports to insert import statement
* bb7649f move builder to godog package
* 2892dd1 add build func documentation

builder.go

@@ -0,0 +1,129 @@
+package godog
+
+import (
+	"bytes"
+	"go/ast"
+	"go/format"
+	"go/parser"
+	"go/token"
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"golang.org/x/tools/imports"
+)
+
+var mainTpl = `package main
+
+import (
+	"github.com/DATA-DOG/godog"
+	"os"
+)
+
+func main() {
+	godog.Run()
+	os.Exit(0)
+}
+`
+
+type builder struct {
+	files map[string]*ast.File
+	fset  *token.FileSet
+}
+
+func newBuilder() *builder {
+	return &builder{
+		files: make(map[string]*ast.File),
+		fset:  token.NewFileSet(),
+	}
+}
+
+func (b *builder) parseFile(path string) error {
+	f, err := parser.ParseFile(b.fset, path, nil, 0)
+	if err != nil {
+		return err
+	}
+	b.deleteMainFunc(f)
+	b.deleteImports(f)
+	b.files[f.Name.Name] = f
+	return nil
+}
+
+func (b *builder) deleteImports(f *ast.File) {
+	var decls []ast.Decl
+	for _, d := range f.Decls {
+		fun, ok := d.(*ast.GenDecl)
+		if !ok {
+			decls = append(decls, d)
+			continue
+		}
+		if fun.Tok != token.IMPORT {
+			decls = append(decls, fun)
+		}
+	}
+	f.Decls = decls
+}
+
+func (b *builder) deleteMainFunc(f *ast.File) {
+	var decls []ast.Decl
+	for _, d := range f.Decls {
+		fun, ok := d.(*ast.FuncDecl)
+		if !ok {
+			decls = append(decls, d)
+			continue
+		}
+		if fun.Name.Name != "main" {
+			decls = append(decls, fun)
+		}
+	}
+	f.Decls = decls
+}
+
+func (b *builder) merge() (*ast.File, error) {
+	f, err := parser.ParseFile(b.fset, "", mainTpl, 0)
+	if err != nil {
+		log.Println("fail here")
+		return nil, err
+	}
+	b.deleteImports(f)
+	b.files["main.go"] = f
+
+	pkg, _ := ast.NewPackage(b.fset, b.files, nil, nil)
+	pkg.Name = "main"
+
+	return ast.MergePackageFiles(pkg, ast.FilterImportDuplicates), nil
+}
+
+// Build creates a runnable godog executable
+// from current package go files
+func Build() ([]byte, error) {
+	b := newBuilder()
+	err := filepath.Walk(".", func(path string, file os.FileInfo, err error) error {
+		if file.IsDir() && file.Name() != "." {
+			return filepath.SkipDir
+		}
+		if err == nil && strings.HasSuffix(path, ".go") {
+			if err := b.parseFile(path); err != nil {
+				return err
+			}
+		}
+		return err
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	merged, err := b.merge()
+	if err != nil {
+		return nil, err
+	}
+
+	var buf bytes.Buffer
+
+	if err := format.Node(&buf, b.fset, merged); err != nil {
+		return nil, err
+	}
+
+	return imports.Process("", buf.Bytes(), nil)
+}

cmd/godog/main.go

@@ -1,5 +1,29 @@
 package main
 
+import (
+	"os"
+
+	"github.com/DATA-DOG/godog"
+)
+
 func main() {
-	// well, not runnable yet
+	builtFile := os.TempDir() + "/godog_build.go"
+	if err := os.Remove(builtFile); err != nil && !os.IsNotExist(err) {
+		panic(err)
+	}
+
+	buf, err := godog.Build()
+	if err != nil {
+		panic(err)
+	}
+
+	w, err := os.Create(builtFile)
+	if err != nil {
+		panic(err)
+	}
+	_, err = w.Write(buf)
+	if err != nil {
+		panic(err)
+	}
+	w.Close()
 }

runner.go

@@ -0,0 +1,7 @@
+package godog
+
+import "log"
+
+func Run() {
+	log.Println("running godoc, num registered steps:", len(stepHandlers))
+}

steps_test.go

@@ -0,0 +1,14 @@
+package godog
+
+import (
+	"log"
+	"regexp"
+)
+
+func init() {
+	f := StepHandlerFunc(func(args ...interface{}) error {
+		log.Println("step triggered")
+		return nil
+	})
+	Step(regexp.MustCompile("hello"), f)
+}