internal/proxydir: add an internal package for file-based proxies

Both packagestest and the gopls regtests need to write module data to
the filesystem in proxy structure. Since this seems like a common and
self-contained concerned, factor this out into a shared package.

Change-Id: I5275dbc0cd7b13290061e8bb559d6dd287fbb275
Reviewed-on: https://go-review.googlesource.com/c/tools/+/227841
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>

1 files changed, 112 insertions, 0 deletions

diff --git a/internal/proxydir/proxydir_test.go b/internal/proxydir/proxydir_test.go
new file mode 100644
index 000000000..54401fb16
--- /dev/null
+++ b/internal/proxydir/proxydir_test.go
@@ -0,0 +1,112 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package proxydir
+
+import (
+	"archive/zip"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestWriteModuleVersion(t *testing.T) {
+	tests := []struct {
+		modulePath, version string
+		files               map[string][]byte
+	}{
+		{
+			modulePath: "mod.test/module",
+			version:    "v1.2.3",
+			files: map[string][]byte{
+				"go.mod":   []byte("module mod.com\n\ngo 1.12"),
+				"const.go": []byte("package module\n\nconst Answer = 42"),
+			},
+		},
+		{
+			modulePath: "mod.test/module",
+			version:    "v1.2.4",
+			files: map[string][]byte{
+				"go.mod":   []byte("module mod.com\n\ngo 1.12"),
+				"const.go": []byte("package module\n\nconst Answer = 43"),
+			},
+		},
+		{
+			modulePath: "mod.test/nogomod",
+			version:    "v0.9.0",
+			files: map[string][]byte{
+				"const.go": []byte("package module\n\nconst Other = \"Other\""),
+			},
+		},
+	}
+	dir, err := ioutil.TempDir("", "proxydirtest-")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(dir)
+	for _, test := range tests {
+		// Since we later assert on the contents of /list, don't use subtests.
+		if err := WriteModuleVersion(dir, test.modulePath, test.version, test.files); err != nil {
+			t.Fatal(err)
+		}
+		rootDir := filepath.Join(dir, filepath.FromSlash(test.modulePath), "@v")
+		gomod, err := ioutil.ReadFile(filepath.Join(rootDir, test.version+".mod"))
+		if err != nil {
+			t.Fatal(err)
+		}
+		wantMod, ok := test.files["go.mod"]
+		if !ok {
+			wantMod = []byte("module " + test.modulePath)
+		}
+		if got, want := string(gomod), string(wantMod); got != want {
+			t.Errorf("reading %s/@v/%s.mod: got %q, want %q", test.modulePath, test.version, got, want)
+		}
+		zr, err := zip.OpenReader(filepath.Join(rootDir, test.version+".zip"))
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer zr.Close()
+
+		for _, zf := range zr.File {
+			r, err := zf.Open()
+			if err != nil {
+				t.Fatal(err)
+			}
+			defer r.Close()
+			content, err := ioutil.ReadAll(r)
+			if err != nil {
+				t.Fatal(err)
+			}
+			name := strings.TrimPrefix(zf.Name, fmt.Sprintf("%s@%s/", test.modulePath, test.version))
+			if got, want := string(content), string(test.files[name]); got != want {
+				t.Errorf("unzipping %q: got %q, want %q", zf.Name, got, want)
+			}
+			delete(test.files, name)
+		}
+		for name := range test.files {
+			t.Errorf("file %q not present in the module zip", name)
+		}
+	}
+
+	lists := []struct {
+		modulePath, want string
+	}{
+		{"mod.test/module", "v1.2.3\nv1.2.4\n"},
+		{"mod.test/nogomod", "v0.9.0\n"},
+	}
+
+	for _, test := range lists {
+		fp := filepath.Join(dir, filepath.FromSlash(test.modulePath), "@v", "list")
+		list, err := ioutil.ReadFile(fp)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if got := string(list); got != test.want {
+			t.Errorf("%q/@v/list: got %q, want %q", test.modulePath, got, test.want)
+		}
+	}
+}