testserver: add artifact mock server

Author: hiddeco

internal/testserver/artifact.go

@@ -0,0 +1,96 @@
+/*
+Copyright 2020 The Flux CD contributors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package testserver
+
+import (
+	"archive/tar"
+	"compress/gzip"
+	"crypto/sha1"
+	"errors"
+	"fmt"
+	"os"
+	"path"
+	"path/filepath"
+)
+
+func NewTempArtifactServer() (*ArtifactServer, error) {
+	server, err := NewTempHTTPServer()
+	if err != nil {
+		return nil, err
+	}
+	artifact := &ArtifactServer{server}
+	return artifact, nil
+}
+
+type ArtifactServer struct {
+	*HTTPServer
+}
+
+type File struct {
+	Name string
+	Body string
+}
+
+// ArtifactFromBytes creates a tar.gz artifact from the given files and
+// returns the file name of the artifact.
+func (s *ArtifactServer) ArtifactFromBytes(files []File) (string, error) {
+	fileName := calculateArtifactName(files)
+	filePath := filepath.Join(s.docroot, fileName)
+	gzFile, err := os.Create(filePath)
+	if err != nil {
+		return "", err
+	}
+	defer gzFile.Close()
+
+	gw := gzip.NewWriter(gzFile)
+	defer gw.Close()
+
+	tw := tar.NewWriter(gw)
+	defer tw.Close()
+
+	for _, file := range files {
+		hdr := &tar.Header{
+			Name: file.Name,
+			Mode: 0600,
+			Size: int64(len(file.Body)),
+		}
+		if err := tw.WriteHeader(hdr); err != nil {
+			return "", err
+		}
+		if _, err := tw.Write([]byte(file.Body)); err != nil {
+			return "", err
+		}
+	}
+	return fileName, nil
+}
+
+// URLForFile returns the URL the given file path can be reached at or
+// an error if the server has not been started.
+func (s *ArtifactServer) URLForFile(file string) (string, error) {
+	if s.URL() == "" {
+		return "", errors.New("server must be started to be able to determine the URL of the given file")
+	}
+	return path.Join(s.URL(), file), nil
+}
+
+func calculateArtifactName(files []File) string {
+	h := sha1.New()
+	for _, f := range files {
+		h.Write([]byte(f.Body))
+	}
+	return fmt.Sprintf("%x.tar.gz", h.Sum(nil))
+}