Share immutable in-memory filesystems

internal/framework/readonlyfs/readonly_fs_test.go

@@ -0,0 +1,153 @@
+package readonlyfs
+
+import (
+	"errors"
+	"io"
+	"io/fs"
+	"testing"
+	"testing/fstest"
+)
+
+func TestNewPassesFSTest(t *testing.T) {
+	for _, test := range []struct {
+		name  string
+		files map[string][]byte
+		paths []string
+	}{
+		{name: "empty", files: map[string][]byte{}, paths: nil},
+		{name: "single file", files: map[string][]byte{"message.txt": []byte("hello")}, paths: []string{"message.txt"}},
+		{name: "nested tree", files: map[string][]byte{"a/one.txt": []byte("one"), "a/b/two.txt": []byte("two")}, paths: []string{"a/one.txt", "a/b/two.txt"}},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			fsys, err := New(test.files)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if err := fstest.TestFS(fsys, test.paths...); err != nil {
+				t.Fatal(err)
+			}
+		})
+	}
+}
+
+func TestNewOwnsConstructionAndReadBytes(t *testing.T) {
+	input := []byte("value")
+	fsys, err := New(map[string][]byte{"value.txt": input})
+	if err != nil {
+		t.Fatal(err)
+	}
+	input[0] = 'x'
+	first, err := fsys.ReadFile("value.txt")
+	if err != nil {
+		t.Fatal(err)
+	}
+	first[0] = 'y'
+	second, err := fsys.ReadFile("value.txt")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(second) != "value" {
+		t.Fatalf("ReadFile() = %q, want owned bytes", second)
+	}
+}
+
+func TestFilesystemStandardBehavior(t *testing.T) {
+	fsys, err := New(map[string][]byte{
+		"z.txt":       []byte("z"),
+		"nested/a.md": []byte("abc"),
+		"nested/b.md": []byte("b"),
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	entries, err := fsys.ReadDir("nested")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(entries) != 2 || entries[0].Name() != "a.md" || entries[1].Name() != "b.md" {
+		t.Fatalf("ReadDir(nested) = %#v, want sorted entries", entries)
+	}
+	info, err := entries[0].Info()
+	if err != nil || info.Mode().Perm() != 0o444 || info.Size() != 3 {
+		t.Fatalf("file info = %#v, %v", info, err)
+	}
+	root, err := fsys.Open(".")
+	if err != nil {
+		t.Fatal(err)
+	}
+	rootInfo, err := root.Stat()
+	if err != nil || !rootInfo.IsDir() || rootInfo.Mode() != fs.ModeDir|0o555 {
+		t.Fatalf("root info = %#v, %v", rootInfo, err)
+	}
+	directory := root.(fs.ReadDirFile)
+	first, err := directory.ReadDir(1)
+	if err != nil || len(first) != 1 || first[0].Name() != "nested" {
+		t.Fatalf("first directory page = %#v, %v", first, err)
+	}
+	second, err := directory.ReadDir(1)
+	if err != nil || len(second) != 1 || second[0].Name() != "z.txt" {
+		t.Fatalf("second directory page = %#v, %v", second, err)
+	}
+	if _, err := directory.ReadDir(1); !errors.Is(err, io.EOF) {
+		t.Fatalf("final directory page error = %v, want EOF", err)
+	}
+	secondRoot, err := fsys.Open(".")
+	if err != nil {
+		t.Fatal(err)
+	}
+	secondDirectory := secondRoot.(fs.ReadDirFile)
+	firstAgain, err := secondDirectory.ReadDir(1)
+	if err != nil || len(firstAgain) != 1 || firstAgain[0].Name() != "nested" {
+		t.Fatalf("independent directory handle page = %#v, %v", firstAgain, err)
+	}
+
+	left, err := fsys.Open("nested/a.md")
+	if err != nil {
+		t.Fatal(err)
+	}
+	right, err := fsys.Open("nested/a.md")
+	if err != nil {
+		t.Fatal(err)
+	}
+	leftByte := make([]byte, 1)
+	rightByte := make([]byte, 1)
+	if _, err := left.Read(leftByte); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := right.Read(rightByte); err != nil {
+		t.Fatal(err)
+	}
+	if string(leftByte) != "a" || string(rightByte) != "a" {
+		t.Fatalf("independent file handles read %q and %q", leftByte, rightByte)
+	}
+	for _, test := range []struct {
+		name string
+		op   func() error
+		want error
+	}{
+		{name: "invalid open path", op: func() error { _, err := fsys.Open("../value"); return err }, want: fs.ErrInvalid},
+		{name: "missing file", op: func() error { _, err := fsys.Open("missing"); return err }, want: fs.ErrNotExist},
+		{name: "read directory", op: func() error { _, err := fsys.ReadFile("nested"); return err }, want: errIsDirectory},
+		{name: "read directory from file", op: func() error { _, err := fsys.ReadDir("z.txt"); return err }, want: errNotDirectory},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			if err := test.op(); !errors.Is(err, test.want) {
+				t.Fatalf("operation error = %v, want %v", err, test.want)
+			}
+		})
+	}
+}
+
+func TestNewRejectsInvalidAndConflictingPaths(t *testing.T) {
+	for _, files := range []map[string][]byte{
+		{".": []byte("root")},
+		{"": []byte("empty")},
+		{"../outside": []byte("outside")},
+		{"nested//file": []byte("invalid")},
+		{"file": []byte("file"), "file/nested": []byte("nested")},
+	} {
+		if _, err := New(files); err == nil {
+			t.Fatalf("New(%#v) error = nil, want rejection", files)
+		}
+	}
+}