archiver creates a single empty file

go.mod

@@ -0,0 +1,10 @@
+module github.com/pzip
+
+go 1.20
+
+require github.com/alecthomas/assert/v2 v2.3.0
+
+require (
+	github.com/alecthomas/repr v0.2.0 // indirect
+	github.com/hexops/gotextdiff v1.0.3 // indirect
+)

go.sum

@@ -0,0 +1,6 @@
+github.com/alecthomas/assert/v2 v2.3.0 h1:mAsH2wmvjsuvyBvAmCtm7zFsBlb8mIHx5ySLVdDZXL0=
+github.com/alecthomas/assert/v2 v2.3.0/go.mod h1:pXcQ2Asjp247dahGEmsZ6ru0UVwnkhktn7S0bBDLxvQ=
+github.com/alecthomas/repr v0.2.0 h1:HAzS41CIzNW5syS8Mf9UwXhNH1J9aix/BvDRf1Ml2Yk=
+github.com/alecthomas/repr v0.2.0/go.mod h1:Fr0507jx4eOXV7AlPV6AVZLYrLIuIeSOWtW57eE/O/4=
+github.com/hexops/gotextdiff v1.0.3 h1:gitA9+qJrrTCsiCl7+kh75nPqQt1cx4ZkudSTLoUqJM=
+github.com/hexops/gotextdiff v1.0.3/go.mod h1:pSWU5MAI3yDq+fZBTazCSJysOMbxWL1BSow5/V2vxeg=

main.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"archive/zip"
+	"io"
+	"os"
+)
+
+func Archive(archive *os.File, r io.Reader) {
+	writer := zip.NewWriter(archive)
+	defer writer.Close()
+
+	writer.Create("hello.txt")
+}
+
+func main() {
+
+}

main_test.go

@@ -0,0 +1,42 @@
+package main
+
+import (
+	"archive/zip"
+	"fmt"
+	"os"
+	"strings"
+	"testing"
+
+	"github.com/alecthomas/assert/v2"
+)
+
+func TestArchive(t *testing.T) {
+	t.Run("archives a single empty file", func(t *testing.T) {
+		file := strings.NewReader("")
+		archive, cleanup := createTempArchive(t, "testdata/archive.zip")
+		defer cleanup()
+
+		Archive(archive, file)
+
+		archiveReader, err := zip.OpenReader(archive.Name())
+		assert.NoError(t, err)
+		defer archiveReader.Close()
+
+		assert.Equal(t, 1, len(archiveReader.File))
+	})
+
+}
+
+func createTempArchive(t testing.TB, name string) (*os.File, func()) {
+	t.Helper()
+
+	archive, err := os.Create(name)
+	assert.NoError(t, err, fmt.Sprintf("could not create archive %s: %v", name, err))
+
+	cleanup := func() {
+		archive.Close()
+		os.RemoveAll(archive.Name())
+	}
+
+	return archive, cleanup
+}