Dumped in posix tests.

samples/memfs/memfs_test.go

@@ -15,6 +15,7 @@
 package memfs_test
 
 import (
+	"io"
 	"io/ioutil"
 	"log"
 	"os"
@@ -79,6 +80,9 @@ func timespecToTime(ts syscall.Timespec) time.Time {
 type MemFSTest struct {
 	clock timeutil.SimulatedClock
 	mfs   *fuse.MountedFileSystem
+
+	// Files to close when tearing down. Nil entries are skipped.
+	toClose []io.Closer
 }
 
 var _ SetUpInterface = &MemFSTest{}
@@ -110,6 +114,18 @@ func (t *MemFSTest) SetUp(ti *TestInfo) {
 }
 
 func (t *MemFSTest) TearDown() {
+	// Close any files we opened.
+	for _, c := range t.toClose {
+		if c == nil {
+			continue
+		}
+
+		err := c.Close()
+		if err != nil {
+			panic(err)
+		}
+	}
+
 	// Unmount the file system. Try again on "resource busy" errors.
 	delay := 10 * time.Millisecond
 	for {
@@ -558,6 +574,164 @@ func (t *MemFSTest) FileReadsAndWrites() {
 	AssertTrue(false, "TODO")
 }
 
-func (t *MemFSTest) FileReadsAndWrites_BeyondEOF() {
-	AssertTrue(false, "TODO")
+func (t *MemFSTest) WriteOverlapsEndOfFile() {
+	var err error
+	var n int
+
+	// Create a file.
+	f, err := os.Create(path.Join(t.mfs.Dir(), "foo"))
+	t.toClose = append(t.toClose, f)
+	AssertEq(nil, err)
+
+	// Make it 4 bytes long.
+	err = f.Truncate(4)
+	AssertEq(nil, err)
+
+	// Write the range [2, 6).
+	n, err = f.WriteAt([]byte("taco"), 2)
+	AssertEq(nil, err)
+	AssertEq(4, n)
+
+	// Read the full contents of the file.
+	contents, err := ioutil.ReadAll(f)
+	AssertEq(nil, err)
+	ExpectEq("\x00\x00taco", string(contents))
+}
+
+func (t *MemFSTest) WriteStartsAtEndOfFile() {
+	var err error
+	var n int
+
+	// Create a file.
+	f, err := os.Create(path.Join(t.mfs.Dir(), "foo"))
+	t.toClose = append(t.toClose, f)
+	AssertEq(nil, err)
+
+	// Make it 2 bytes long.
+	err = f.Truncate(2)
+	AssertEq(nil, err)
+
+	// Write the range [2, 6).
+	n, err = f.WriteAt([]byte("taco"), 2)
+	AssertEq(nil, err)
+	AssertEq(4, n)
+
+	// Read the full contents of the file.
+	contents, err := ioutil.ReadAll(f)
+	AssertEq(nil, err)
+	ExpectEq("\x00\x00taco", string(contents))
+}
+
+func (t *MemFSTest) WriteStartsPastEndOfFile() {
+	var err error
+	var n int
+
+	// Create a file.
+	f, err := os.Create(path.Join(t.mfs.Dir(), "foo"))
+	t.toClose = append(t.toClose, f)
+	AssertEq(nil, err)
+
+	// Write the range [2, 6).
+	n, err = f.WriteAt([]byte("taco"), 2)
+	AssertEq(nil, err)
+	AssertEq(4, n)
+
+	// Read the full contents of the file.
+	contents, err := ioutil.ReadAll(f)
+	AssertEq(nil, err)
+	ExpectEq("\x00\x00taco", string(contents))
+}
+
+func (t *MemFSTest) WriteAtDoesntChangeOffset_NotAppendMode() {
+	var err error
+	var n int
+
+	// Create a file.
+	f, err := os.Create(path.Join(t.mfs.Dir(), "foo"))
+	t.toClose = append(t.toClose, f)
+	AssertEq(nil, err)
+
+	// Make it 16 bytes long.
+	err = f.Truncate(16)
+	AssertEq(nil, err)
+
+	// Seek to offset 4.
+	_, err = f.Seek(4, 0)
+	AssertEq(nil, err)
+
+	// Write the range [10, 14).
+	n, err = f.WriteAt([]byte("taco"), 2)
+	AssertEq(nil, err)
+	AssertEq(4, n)
+
+	// We should still be at offset 4.
+	offset, err := getFileOffset(f)
+	AssertEq(nil, err)
+	ExpectEq(4, offset)
+}
+
+func (t *MemFSTest) WriteAtDoesntChangeOffset_AppendMode() {
+	var err error
+	var n int
+
+	// Create a file in append mode.
+	f, err := os.OpenFile(
+		path.Join(t.mfs.Dir(), "foo"),
+		os.O_RDWR|os.O_APPEND|os.O_CREATE,
+		0600)
+
+	t.toClose = append(t.toClose, f)
+	AssertEq(nil, err)
+
+	// Make it 16 bytes long.
+	err = f.Truncate(16)
+	AssertEq(nil, err)
+
+	// Seek to offset 4.
+	_, err = f.Seek(4, 0)
+	AssertEq(nil, err)
+
+	// Write the range [10, 14).
+	n, err = f.WriteAt([]byte("taco"), 2)
+	AssertEq(nil, err)
+	AssertEq(4, n)
+
+	// We should still be at offset 4.
+	offset, err := getFileOffset(f)
+	AssertEq(nil, err)
+	ExpectEq(4, offset)
+}
+
+func (t *MemFSTest) ReadsPastEndOfFile() {
+	var err error
+	var n int
+	buf := make([]byte, 1024)
+
+	// Create a file.
+	f, err := os.Create(path.Join(t.mfs.Dir(), "foo"))
+	t.toClose = append(t.toClose, f)
+	AssertEq(nil, err)
+
+	// Give it some contents.
+	n, err = f.Write([]byte("taco"))
+	AssertEq(nil, err)
+	AssertEq(4, n)
+
+	// Read a range overlapping EOF.
+	n, err = f.ReadAt(buf[:4], 2)
+	AssertEq(io.EOF, err)
+	ExpectEq(2, n)
+	ExpectEq("co", string(buf[:n]))
+
+	// Read a range starting at EOF.
+	n, err = f.ReadAt(buf[:4], 4)
+	AssertEq(io.EOF, err)
+	ExpectEq(0, n)
+	ExpectEq("", string(buf[:n]))
+
+	// Read a range starting past EOF.
+	n, err = f.ReadAt(buf[:4], 100)
+	AssertEq(io.EOF, err)
+	ExpectEq(0, n)
+	ExpectEq("", string(buf[:n]))
 }