slicer/test: Support for custom packages

Currently we only test with the embedded base-files files package. This
quite limits what we can test. But since commit a3315e3
("testutil/pkgdata: Create deb programatically") we have the ability to
define our own custom package content.

Add support for testing with custom packages. These can be defined in
each test case per archive name. The content can be defined directly in
test case definition with the help of testutil.MustMakeDeb().

The package content is wrapped in the testPackage structure. This
introduces one level of nesting in each test case package definition. In
future, we will add package metadata to the package definition, namely
version. So wrapping the package content in the structure now and later
just adding a new field to it the structure later will make the future
diff much smaller.

internal/slicer/slicer_test.go

@@ -16,9 +16,20 @@ import (
 	"github.com/canonical/chisel/internal/testutil"
 )
 
+var (
+	Reg = testutil.Reg
+	Dir = testutil.Dir
+	Lnk = testutil.Lnk
+)
+
+type testPackage struct {
+	content []byte
+}
+
 type slicerTest struct {
 	summary string
 	arch    string
+	pkgs    map[string]map[string]testPackage
 	release map[string]string
 	slices  []setup.SliceKey
 	hackopt func(c *C, opts *slicer.RunOptions)
@@ -515,6 +526,77 @@ var slicerTests = []slicerTest{{
 		"/usr/bin/":      "dir 0755",
 		"/usr/bin/hello": "file 0775 eaf29575",
 	},
+}, {
+	summary: "Custom archives with custom packages",
+	pkgs: map[string]map[string]testPackage{
+		"leptons": {
+			"electron": testPackage{
+				content: testutil.MustMakeDeb([]testutil.TarEntry{
+					Dir(0755, "./"),
+					Dir(0755, "./mass/"),
+					Reg(0644, "./mass/electron", "9.1093837015E−31 kg\n"),
+					Dir(0755, "./usr/"),
+					Dir(0755, "./usr/share/"),
+					Dir(0755, "./usr/share/doc/"),
+					Dir(0755, "./usr/share/doc/electron/"),
+					Reg(0644, "./usr/share/doc/electron/copyright", ""),
+				}),
+			},
+		},
+		"hadrons": {
+			"proton": testPackage{
+				content: testutil.MustMakeDeb([]testutil.TarEntry{
+					Dir(0755, "./"),
+					Dir(0755, "./mass/"),
+					Reg(0644, "./mass/proton", "1.67262192369E−27 kg\n"),
+				}),
+			},
+		},
+	},
+	release: map[string]string{
+		"chisel.yaml": `
+			format: chisel-v1
+			archives:
+				leptons:
+					version: 1
+					suites: [main]
+					components: [main, universe]
+					default: true
+				hadrons:
+					version: 1
+					suites: [main]
+					components: [main]
+		`,
+		"slices/mydir/electron.yaml": `
+			package: electron
+			slices:
+				mass:
+					contents:
+						/mass/electron:
+		`,
+		"slices/mydir/proton.yaml": `
+			package: proton
+			archive: hadrons
+			slices:
+				mass:
+					contents:
+						/mass/proton:
+		`,
+	},
+	slices: []setup.SliceKey{
+		{"electron", "mass"},
+		{"proton", "mass"},
+	},
+	result: map[string]string{
+		"/mass/":                            "dir 0755",
+		"/mass/electron":                    "file 0644 a1258e30",
+		"/mass/proton":                      "file 0644 a2390d10",
+		"/usr/":                             "dir 0755",
+		"/usr/share/":                       "dir 0755",
+		"/usr/share/doc/":                   "dir 0755",
+		"/usr/share/doc/electron/":          "dir 0755",
+		"/usr/share/doc/electron/copyright": "file 0644 empty",
+	},
 }}
 
 const defaultChiselYaml = `
@@ -527,7 +609,7 @@ const defaultChiselYaml = `
 
 type testArchive struct {
 	options archive.Options
-	pkgs    map[string][]byte
+	pkgs    map[string]testPackage
 }
 
 func (a *testArchive) Options() *archive.Options {
@@ -536,7 +618,7 @@ func (a *testArchive) Options() *archive.Options {
 
 func (a *testArchive) Fetch(pkg string) (io.ReadCloser, error) {
 	if data, ok := a.pkgs[pkg]; ok {
-		return io.NopCloser(bytes.NewBuffer(data)), nil
+		return io.NopCloser(bytes.NewBuffer(data.content)), nil
 	}
 	return nil, fmt.Errorf("attempted to open %q package", pkg)
 }
@@ -569,16 +651,23 @@ func (s *S) TestRun(c *C) {
 		selection, err := setup.Select(release, test.slices)
 		c.Assert(err, IsNil)
 
-		pkgs := map[string][]byte{
-			"base-files": testutil.PackageData["base-files"],
+		pkgs := map[string]testPackage{
+			"base-files": testPackage{content: testutil.PackageData["base-files"]},
 		}
 		for name, entries := range packageEntries {
 			deb, err := testutil.MakeDeb(entries)
 			c.Assert(err, IsNil)
-			pkgs[name] = deb
+			pkgs[name] = testPackage{content: deb}
 		}
 		archives := map[string]archive.Archive{}
 		for name, setupArchive := range release.Archives {
+			var archivePkgs map[string]testPackage
+			if test.pkgs != nil {
+				archivePkgs = test.pkgs[name]
+			}
+			if archivePkgs == nil {
+				archivePkgs = pkgs
+			}
 			archive := &testArchive{
 				options: archive.Options{
 					Label:      setupArchive.Name,
@@ -587,7 +676,7 @@ func (s *S) TestRun(c *C) {
 					Components: setupArchive.Components,
 					Arch:       test.arch,
 				},
-				pkgs: pkgs,
+				pkgs: archivePkgs,
 			}
 			archives[name] = archive
 		}
@@ -611,8 +700,15 @@ func (s *S) TestRun(c *C) {
 
 		if test.result != nil {
 			result := make(map[string]string, len(copyrightEntries)+len(test.result))
-			for k, v := range copyrightEntries {
-				result[k] = v
+			if test.pkgs == nil {
+				// This was added in order to not specify copyright entries for each
+				// existing test. These tests use only the base-files embedded
+				// package. Custom packages may not include copyright entries
+				// though. So if a test defines any custom packages, it must include
+				// copyright entries explicitly in the results.
+				for k, v := range copyrightEntries {
+					result[k] = v
+				}
 			}
 			for k, v := range test.result {
 				result[k] = v