Add ensure-file parser package.

cipd/client/cipd/ensure/good_test.go

Index: cipd/client/cipd/ensure/good_test.go
diff --git a/cipd/client/cipd/ensure/good_test.go b/cipd/client/cipd/ensure/good_test.go
new file mode 100644
index 0000000000000000000000000000000000000000..80b8f7e938f00bd5b1ecd49cb9aafdfba0136208
--- /dev/null
+++ b/cipd/client/cipd/ensure/good_test.go
@@ -0,0 +1,145 @@
+// Copyright 2017 The LUCI Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package ensure
+
+import (
+	"bytes"
+	"errors"
+	"strings"
+	"testing"
+
+	"github.com/luci/luci-go/cipd/client/cipd/common"
+	. "github.com/smartystreets/goconvey/convey"
+)
+
+func f(lines ...string) string {
+	return strings.Join(lines, "\n")
+}
+
+func p(pkg, ver string) common.Pin {
+	return common.Pin{PackageName: pkg, InstanceID: ver}
+}
+
+var goodEnsureFiles = []struct {
+	name   string
+	file   string
+	expect *ResolvedFile
+}{
+	{
+		"old_style",
+		f(
+			"# comment",
+			"",
+			"path/to/package deadbeefdeadbeefdeadbeefdeadbeefdeadbeef",
+			"path/to/other_package some_tag:version",
+			"path/to/yet_another a_ref",
+		),
+		&ResolvedFile{"", map[string][]common.Pin{
+			"": {
+				p("path/to/package", "deadbeefdeadbeefdeadbeefdeadbeefdeadbeef"),
+				p("path/to/other_package", "some_tag:version"),
+				p("path/to/yet_another", "a_ref"),
+			},
+		}},
+	},
+
+	{
+		"templates",
+		f(
+			"path/to/package/${platform}-${arch} latest",
+		),
+		&ResolvedFile{"", map[string][]common.Pin{
+			"": {
+				p("path/to/package/test_plat-test_arch", "latest"),
+			},
+		}},
+	},
+
+	{
+		"optional_templates",
+		f(
+			"path/to/package/${platform}-${arch=neep,test_arch} latest",
+		),
+		&ResolvedFile{"", map[string][]common.Pin{
+			"": {p("path/to/package/test_plat-test_arch", "latest")},
+		}},
+	},
+
+	{
+		"optional_templates_no_match",
+		f(
+			"path/to/package/${platform=spaz}-${arch=neep,test_arch} latest",
+		),
+		&ResolvedFile{"", map[string][]common.Pin{}},
+	},
+
+	{
+		"Root directives",
+		f(
+			"some/package latest",
+			"",
+			"@Root a/subdir with spaces",
+			"some/package canary",
+			"some/other/package tag:value",
+			"",
+			"@Root", // reset back to empty
+			"cool/package beef",
+		),
+		&ResolvedFile{"", map[string][]common.Pin{
+			"": {
+				p("some/package", "latest"),
+				p("cool/package", "beef"),
+			},
+			"a/subdir with spaces": {
+				p("some/package", "canary"),
+				p("some/other/package", "tag:value"),
+			},
+		}},
+	},
+
+	{
+		"ServiceURL setting",
+		f(
+			"$ServiceURL https://cipd.example.com/path/to/thing",
+			"",
+			"some/package version",
+		),
+		&ResolvedFile{"https://cipd.example.com/path/to/thing", map[string][]common.Pin{
+			"": {
+				p("some/package", "version"),
+			},
+		}},
+	},
+
+	{
+		"empty",
+		"",
+		&ResolvedFile{},
+	},
+}
+
+func testResolver(pkg, vers string) (common.Pin, error) {
+	if strings.Contains(vers, "error") {
+		return p("", ""), errors.New("testResolver returned error")
+	}
+	return p(pkg, vers), nil
+}
+
+func TestGoodEnsureFiles(t *testing.T) {
+	t.Parallel()
+
+	Convey("good ensure files", t, func() {
+		for _, tc := range goodEnsureFiles {
+			Convey(tc.name, func() {
+				buf := bytes.NewBufferString(tc.file)
+				f, err := ParseFile(buf)
+				So(err, ShouldBeNil)
+				rf, err := f.ResolveWith("test_arch", "test_plat", testResolver)
+				So(err, ShouldBeNil)
+				So(rf, ShouldResemble, tc.expect)
+			})
+		}
+	})
+}