Add zipfile module (#826)

- Also required for the MARTA sample app using GTFS protocol buffers as their
- Basically just importing a starlib module, but wrapping slightly to make usage more consistent with other pixlet
- The style that starlib used here is familiar from working with starlark at Google, but my guess is it's not familiar to most users, and it also isn't consistent with other starlib modules ¯\_(ツ)_/¯

docs/modules.md

@@ -29,6 +29,7 @@ individual modules, please refer to the Starlib documentation.
 | Module | Description |
 | --- | --- |
 | [`compress/gzip.star`](https://github.com/qri-io/starlib/blob/master/compress/gzip) | gzip decompressing |
+| [`compress/zipfile.star`](https://github.com/qri-io/starlib/blob/master/zipfile) | zip decompressing |
 | [`encoding/base64.star`](https://github.com/qri-io/starlib/tree/master/encoding/base64) | Base 64 encoding and decoding |
 | [`encoding/csv.star`](https://github.com/qri-io/starlib/tree/master/encoding/csv) | CSV decoding |
 | [`encoding/json.star`](https://github.com/qri-io/starlib/tree/master/encoding/json) | JSON encoding and decoding |

runtime/applet.go

@@ -13,6 +13,7 @@ import (
 	starlibhash "github.com/qri-io/starlib/hash"
 	starlibhtml "github.com/qri-io/starlib/html"
 	starlibre "github.com/qri-io/starlib/re"
+	starlibzip "github.com/qri-io/starlib/zipfile"
 	starlibjson "go.starlark.net/lib/json"
 	starlibmath "go.starlark.net/lib/math"
 	starlibtime "go.starlark.net/lib/time"
@@ -320,6 +321,19 @@ func (a *Applet) loadModule(thread *starlark.Thread, module string) (starlark.St
 			starlibgzip.Module.Name: starlibgzip.Module,
 		}, nil
 
+	case "compress/zipfile.star":
+		// Starlib expects you to load the ZipFile function directly, rather than having it be part of a namespace.
+		// Wraps this to be more consistent with other pixlet modules, as follows:
+		//   load("compress/zipfile.star", "zipfile")
+		//   archive = zipfile.ZipFile("/tmp/foo.zip")
+		m, _ := starlibzip.LoadModule()
+		return starlark.StringDict{
+			"zipfile": &starlarkstruct.Module{
+				Name: "zipfile",
+				Members: m,
+			},
+		}, nil
+
 	case "encoding/base64.star":
 		return starlibbase64.LoadModule()
 

runtime/applet_test.go

@@ -1,6 +1,8 @@
 package runtime
 
 import (
+	"archive/zip"
+	"bytes"
 	"fmt"
 	"testing"
 
@@ -263,7 +265,7 @@ def main():
 }
 
 func TestTimezoneDatabase(t *testing.T) {
-	src:= `
+	src := `
 load("render.star", "render")
 load("time.star", "time")
 def main():
@@ -279,4 +281,56 @@ def main():
 	assert.NoError(t, err)
 }
 
+func TestZipModule(t *testing.T) {
+	// Create a new zip file to read from starlark
+	// https://go.dev/src/archive/zip/example_test.go
+	buf := new(bytes.Buffer)
+	w := zip.NewWriter(buf)
+	var files = []struct {
+		Name, Body string
+	}{
+		{"readme.txt", "This archive contains some text files."},
+		{"gopher.txt", "Gopher names:\nGeorge\nGeoffrey\nGonzo"},
+		{"todo.txt", "Get animal handling licence.\nWrite more examples."},
+	}
+	for _, file := range files {
+		f, err := w.Create(file.Name)
+		assert.NoError(t, err)
+		_, err = f.Write([]byte(file.Body))
+		assert.NoError(t, err)
+	}
+	err := w.Close()
+	assert.NoError(t, err)
+
+	// override the print function of the thread so we can check we got correct
+	// values from the zip module.
+	var printedText []string
+	initializer := func(thread *starlark.Thread) *starlark.Thread {
+		thread.Print = func(thread *starlark.Thread, msg string) {
+			printedText = append(printedText, msg)
+		}
+		return thread
+	}
+
+	src := `
+load("compress/zipfile.star", "zipfile")
+def main(config):
+    z = zipfile.ZipFile(config.get("ZIP_BYTES"))
+    print(z.namelist())
+    zf = z.open("readme.txt")
+    print(zf.read())
+    return []
+`
+
+	app := &Applet{}
+	err = app.Load("test.star", []byte(src), nil)
+	_, err = app.Run(map[string]string{"ZIP_BYTES": buf.String()}, initializer)
+	assert.NoError(t, err)
+
+	assert.Equal(t, []string{
+		"[\"readme.txt\", \"gopher.txt\", \"todo.txt\"]",
+		"This archive contains some text files.",
+	}, printedText)
+}
+
 // TODO: test Screens, especially Screens.Render()