X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/7327d3b601a50148abead0ae226176a40937e363..57d3837ca9a8c5e4e71f9741931cc67e908fb3dd:/services/keepstore/volume_generic_test.go

diff --git a/services/keepstore/volume_generic_test.go b/services/keepstore/volume_generic_test.go
index 0c0629c2a1..61088f10fa 100644
--- a/services/keepstore/volume_generic_test.go
+++ b/services/keepstore/volume_generic_test.go
@@ -2,54 +2,687 @@ package main
 
 import (
 	"bytes"
+	"crypto/md5"
+	"fmt"
 	"os"
+	"regexp"
+	"sort"
+	"strings"
 	"testing"
 	"time"
 )
 
 // A TestableVolumeFactory returns a new TestableVolume. The factory
-// function, and the TestableVolume it returns, can use t to write
+// function, and the TestableVolume it returns, can use "t" to write
 // logs, fail the current test, etc.
 type TestableVolumeFactory func(t *testing.T) TestableVolume
 
 // DoGenericVolumeTests runs a set of tests that every TestableVolume
-// is expected to pass. It calls factory to create a new
-// TestableVolume for each test case, to avoid leaking state between
-// tests.
+// is expected to pass. It calls factory to create a new TestableVolume
+// for each test case, to avoid leaking state between tests.
 func DoGenericVolumeTests(t *testing.T, factory TestableVolumeFactory) {
+	testGet(t, factory)
+	testGetNoSuchBlock(t, factory)
+
+	testCompareNonexistent(t, factory)
+	testCompareSameContent(t, factory, TestHash, TestBlock)
+	testCompareSameContent(t, factory, EmptyHash, EmptyBlock)
+	testCompareWithCollision(t, factory, TestHash, TestBlock, []byte("baddata"))
+	testCompareWithCollision(t, factory, TestHash, TestBlock, EmptyBlock)
+	testCompareWithCollision(t, factory, EmptyHash, EmptyBlock, TestBlock)
+	testCompareWithCorruptStoredData(t, factory, TestHash, TestBlock, []byte("baddata"))
+	testCompareWithCorruptStoredData(t, factory, TestHash, TestBlock, EmptyBlock)
+	testCompareWithCorruptStoredData(t, factory, EmptyHash, EmptyBlock, []byte("baddata"))
+
+	testPutBlockWithSameContent(t, factory, TestHash, TestBlock)
+	testPutBlockWithSameContent(t, factory, EmptyHash, EmptyBlock)
+	testPutBlockWithDifferentContent(t, factory, TestHash, TestBlock, TestBlock2)
+	testPutBlockWithDifferentContent(t, factory, TestHash, EmptyBlock, TestBlock)
+	testPutBlockWithDifferentContent(t, factory, TestHash, TestBlock, EmptyBlock)
+	testPutBlockWithDifferentContent(t, factory, EmptyHash, EmptyBlock, TestBlock)
+	testPutMultipleBlocks(t, factory)
+
+	testPutAndTouch(t, factory)
+	testTouchNoSuchBlock(t, factory)
+
+	testMtimeNoSuchBlock(t, factory)
+
+	testIndexTo(t, factory)
+
 	testDeleteNewBlock(t, factory)
 	testDeleteOldBlock(t, factory)
+	testDeleteNoSuchBlock(t, factory)
+
+	testStatus(t, factory)
+
+	testString(t, factory)
+
+	testUpdateReadOnly(t, factory)
+
+	testGetConcurrent(t, factory)
+	testPutConcurrent(t, factory)
+
+	testPutFullBlock(t, factory)
+}
+
+// Put a test block, get it and verify content
+// Test should pass for both writable and read-only volumes
+func testGet(t *testing.T, factory TestableVolumeFactory) {
+	v := factory(t)
+	defer v.Teardown()
+
+	v.PutRaw(TestHash, TestBlock)
+
+	buf, err := v.Get(TestHash)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	bufs.Put(buf)
+
+	if bytes.Compare(buf, TestBlock) != 0 {
+		t.Errorf("expected %s, got %s", string(TestBlock), string(buf))
+	}
+}
+
+// Invoke get on a block that does not exist in volume; should result in error
+// Test should pass for both writable and read-only volumes
+func testGetNoSuchBlock(t *testing.T, factory TestableVolumeFactory) {
+	v := factory(t)
+	defer v.Teardown()
+
+	if _, err := v.Get(TestHash2); err == nil {
+		t.Errorf("Expected error while getting non-existing block %v", TestHash2)
+	}
+}
+
+// Compare() should return os.ErrNotExist if the block does not exist.
+// Otherwise, writing new data causes CompareAndTouch() to generate
+// error logs even though everything is working fine.
+func testCompareNonexistent(t *testing.T, factory TestableVolumeFactory) {
+	v := factory(t)
+	defer v.Teardown()
+
+	err := v.Compare(TestHash, TestBlock)
+	if err != os.ErrNotExist {
+		t.Errorf("Got err %T %q, expected os.ErrNotExist", err, err)
+	}
+}
+
+// Put a test block and compare the locator with same content
+// Test should pass for both writable and read-only volumes
+func testCompareSameContent(t *testing.T, factory TestableVolumeFactory, testHash string, testData []byte) {
+	v := factory(t)
+	defer v.Teardown()
+
+	v.PutRaw(testHash, testData)
+
+	// Compare the block locator with same content
+	err := v.Compare(testHash, testData)
+	if err != nil {
+		t.Errorf("Got err %q, expected nil", err)
+	}
+}
+
+// Test behavior of Compare() when stored data matches expected
+// checksum but differs from new data we need to store. Requires
+// testHash = md5(testDataA).
+//
+// Test should pass for both writable and read-only volumes
+func testCompareWithCollision(t *testing.T, factory TestableVolumeFactory, testHash string, testDataA, testDataB []byte) {
+	v := factory(t)
+	defer v.Teardown()
+
+	v.PutRaw(testHash, testDataA)
+
+	// Compare the block locator with different content; collision
+	err := v.Compare(TestHash, testDataB)
+	if err == nil {
+		t.Errorf("Got err nil, expected error due to collision")
+	}
+}
+
+// Test behavior of Compare() when stored data has become
+// corrupted. Requires testHash = md5(testDataA) != md5(testDataB).
+//
+// Test should pass for both writable and read-only volumes
+func testCompareWithCorruptStoredData(t *testing.T, factory TestableVolumeFactory, testHash string, testDataA, testDataB []byte) {
+	v := factory(t)
+	defer v.Teardown()
+
+	v.PutRaw(TestHash, testDataB)
+
+	err := v.Compare(testHash, testDataA)
+	if err == nil || err == CollisionError {
+		t.Errorf("Got err %+v, expected non-collision error", err)
+	}
+}
+
+// Put a block and put again with same content
+// Test is intended for only writable volumes
+func testPutBlockWithSameContent(t *testing.T, factory TestableVolumeFactory, testHash string, testData []byte) {
+	v := factory(t)
+	defer v.Teardown()
+
+	if v.Writable() == false {
+		return
+	}
+
+	err := v.Put(testHash, testData)
+	if err != nil {
+		t.Errorf("Got err putting block %q: %q, expected nil", TestBlock, err)
+	}
+
+	err = v.Put(testHash, testData)
+	if err != nil {
+		t.Errorf("Got err putting block second time %q: %q, expected nil", TestBlock, err)
+	}
+}
+
+// Put a block and put again with different content
+// Test is intended for only writable volumes
+func testPutBlockWithDifferentContent(t *testing.T, factory TestableVolumeFactory, testHash string, testDataA, testDataB []byte) {
+	v := factory(t)
+	defer v.Teardown()
+
+	if v.Writable() == false {
+		return
+	}
+
+	err := v.Put(testHash, testDataA)
+	if err != nil {
+		t.Errorf("Got err putting block %q: %q, expected nil", testDataA, err)
+	}
+
+	putErr := v.Put(testHash, testDataB)
+	buf, getErr := v.Get(testHash)
+	if putErr == nil {
+		// Put must not return a nil error unless it has
+		// overwritten the existing data.
+		if bytes.Compare(buf, testDataB) != 0 {
+			t.Errorf("Put succeeded but Get returned %+q, expected %+q", buf, testDataB)
+		}
+	} else {
+		// It is permissible for Put to fail, but it must
+		// leave us with either the original data, the new
+		// data, or nothing at all.
+		if getErr == nil && bytes.Compare(buf, testDataA) != 0 && bytes.Compare(buf, testDataB) != 0 {
+			t.Errorf("Put failed but Get returned %+q, which is neither %+q nor %+q", buf, testDataA, testDataB)
+		}
+	}
+	if getErr == nil {
+		bufs.Put(buf)
+	}
+}
+
+// Put and get multiple blocks
+// Test is intended for only writable volumes
+func testPutMultipleBlocks(t *testing.T, factory TestableVolumeFactory) {
+	v := factory(t)
+	defer v.Teardown()
+
+	if v.Writable() == false {
+		return
+	}
+
+	err := v.Put(TestHash, TestBlock)
+	if err != nil {
+		t.Errorf("Got err putting block %q: %q, expected nil", TestBlock, err)
+	}
+
+	err = v.Put(TestHash2, TestBlock2)
+	if err != nil {
+		t.Errorf("Got err putting block %q: %q, expected nil", TestBlock2, err)
+	}
+
+	err = v.Put(TestHash3, TestBlock3)
+	if err != nil {
+		t.Errorf("Got err putting block %q: %q, expected nil", TestBlock3, err)
+	}
+
+	data, err := v.Get(TestHash)
+	if err != nil {
+		t.Error(err)
+	} else {
+		if bytes.Compare(data, TestBlock) != 0 {
+			t.Errorf("Block present, but got %+q, expected %+q", data, TestBlock)
+		}
+		bufs.Put(data)
+	}
+
+	data, err = v.Get(TestHash2)
+	if err != nil {
+		t.Error(err)
+	} else {
+		if bytes.Compare(data, TestBlock2) != 0 {
+			t.Errorf("Block present, but got %+q, expected %+q", data, TestBlock2)
+		}
+		bufs.Put(data)
+	}
+
+	data, err = v.Get(TestHash3)
+	if err != nil {
+		t.Error(err)
+	} else {
+		if bytes.Compare(data, TestBlock3) != 0 {
+			t.Errorf("Block present, but to %+q, expected %+q", data, TestBlock3)
+		}
+		bufs.Put(data)
+	}
+}
+
+// testPutAndTouch
+//   Test that when applying PUT to a block that already exists,
+//   the block's modification time is updated.
+// Test is intended for only writable volumes
+func testPutAndTouch(t *testing.T, factory TestableVolumeFactory) {
+	v := factory(t)
+	defer v.Teardown()
+
+	if v.Writable() == false {
+		return
+	}
+
+	if err := v.Put(TestHash, TestBlock); err != nil {
+		t.Error(err)
+	}
+
+	// We'll verify { t0 < threshold < t1 }, where t0 is the
+	// existing block's timestamp on disk before Put() and t1 is
+	// its timestamp after Put().
+	threshold := time.Now().Add(-time.Second)
+
+	// Set the stored block's mtime far enough in the past that we
+	// can see the difference between "timestamp didn't change"
+	// and "timestamp granularity is too low".
+	v.TouchWithDate(TestHash, time.Now().Add(-20*time.Second))
+
+	// Make sure v.Mtime() agrees the above Utime really worked.
+	if t0, err := v.Mtime(TestHash); err != nil || t0.IsZero() || !t0.Before(threshold) {
+		t.Errorf("Setting mtime failed: %v, %v", t0, err)
+	}
+
+	// Write the same block again.
+	if err := v.Put(TestHash, TestBlock); err != nil {
+		t.Error(err)
+	}
+
+	// Verify threshold < t1
+	if t1, err := v.Mtime(TestHash); err != nil {
+		t.Error(err)
+	} else if t1.Before(threshold) {
+		t.Errorf("t1 %v should be >= threshold %v after v.Put ", t1, threshold)
+	}
+}
+
+// Touching a non-existing block should result in error.
+// Test should pass for both writable and read-only volumes
+func testTouchNoSuchBlock(t *testing.T, factory TestableVolumeFactory) {
+	v := factory(t)
+	defer v.Teardown()
+
+	if err := v.Touch(TestHash); err == nil {
+		t.Error("Expected error when attempted to touch a non-existing block")
+	}
 }
 
-// Calling Delete() for a block immediately after writing it should
-// neither delete the data nor return an error.
+// Invoking Mtime on a non-existing block should result in error.
+// Test should pass for both writable and read-only volumes
+func testMtimeNoSuchBlock(t *testing.T, factory TestableVolumeFactory) {
+	v := factory(t)
+	defer v.Teardown()
+
+	if _, err := v.Mtime("12345678901234567890123456789012"); err == nil {
+		t.Error("Expected error when updating Mtime on a non-existing block")
+	}
+}
+
+// Put a few blocks and invoke IndexTo with:
+// * no prefix
+// * with a prefix
+// * with no such prefix
+// Test should pass for both writable and read-only volumes
+func testIndexTo(t *testing.T, factory TestableVolumeFactory) {
+	v := factory(t)
+	defer v.Teardown()
+
+	v.PutRaw(TestHash, TestBlock)
+	v.PutRaw(TestHash2, TestBlock2)
+	v.PutRaw(TestHash3, TestBlock3)
+
+	// Blocks whose names aren't Keep hashes should be omitted from
+	// index
+	v.PutRaw("fffffffffnotreallyahashfffffffff", nil)
+	v.PutRaw("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF", nil)
+	v.PutRaw("f0000000000000000000000000000000f", nil)
+	v.PutRaw("f00", nil)
+
+	buf := new(bytes.Buffer)
+	v.IndexTo("", buf)
+	indexRows := strings.Split(string(buf.Bytes()), "\n")
+	sort.Strings(indexRows)
+	sortedIndex := strings.Join(indexRows, "\n")
+	m, err := regexp.MatchString(
+		`^\n`+TestHash+`\+\d+ \d+\n`+
+			TestHash3+`\+\d+ \d+\n`+
+			TestHash2+`\+\d+ \d+$`,
+		sortedIndex)
+	if err != nil {
+		t.Error(err)
+	} else if !m {
+		t.Errorf("Got index %q for empty prefix", sortedIndex)
+	}
+
+	for _, prefix := range []string{"f", "f15", "f15ac"} {
+		buf = new(bytes.Buffer)
+		v.IndexTo(prefix, buf)
+
+		m, err := regexp.MatchString(`^`+TestHash2+`\+\d+ \d+\n$`, string(buf.Bytes()))
+		if err != nil {
+			t.Error(err)
+		} else if !m {
+			t.Errorf("Got index %q for prefix %s", string(buf.Bytes()), prefix)
+		}
+	}
+
+	for _, prefix := range []string{"zero", "zip", "zilch"} {
+		buf = new(bytes.Buffer)
+		v.IndexTo(prefix, buf)
+		if err != nil {
+			t.Errorf("Got error on IndexTo with no such prefix %v", err.Error())
+		} else if buf.Len() != 0 {
+			t.Errorf("Expected empty list for IndexTo with no such prefix %s", prefix)
+		}
+	}
+}
+
+// Calling Delete() for a block immediately after writing it (not old enough)
+// should neither delete the data nor return an error.
+// Test is intended for only writable volumes
 func testDeleteNewBlock(t *testing.T, factory TestableVolumeFactory) {
 	v := factory(t)
 	defer v.Teardown()
-	v.Put(TEST_HASH, TEST_BLOCK)
+	blobSignatureTTL = 300 * time.Second
+
+	if v.Writable() == false {
+		return
+	}
 
-	if err := v.Delete(TEST_HASH); err != nil {
+	v.Put(TestHash, TestBlock)
+
+	if err := v.Delete(TestHash); err != nil {
 		t.Error(err)
 	}
-	if data, err := v.Get(TEST_HASH); err != nil {
+	data, err := v.Get(TestHash)
+	if err != nil {
 		t.Error(err)
-	} else if bytes.Compare(data, TEST_BLOCK) != 0 {
-		t.Error("Block still present, but content is incorrect: %+v != %+v", data, TEST_BLOCK)
+	} else {
+		if bytes.Compare(data, TestBlock) != 0 {
+			t.Errorf("Got data %+q, expected %+q", data, TestBlock)
+		}
+		bufs.Put(data)
 	}
 }
 
 // Calling Delete() for a block with a timestamp older than
-// blob_signature_ttl seconds in the past should delete the data.
+// blobSignatureTTL seconds in the past should delete the data.
+// Test is intended for only writable volumes
 func testDeleteOldBlock(t *testing.T, factory TestableVolumeFactory) {
 	v := factory(t)
 	defer v.Teardown()
-	v.Put(TEST_HASH, TEST_BLOCK)
-	v.TouchWithDate(TEST_HASH, time.Now().Add(-2*blob_signature_ttl*time.Second))
+	blobSignatureTTL = 300 * time.Second
+
+	if v.Writable() == false {
+		return
+	}
+
+	v.Put(TestHash, TestBlock)
+	v.TouchWithDate(TestHash, time.Now().Add(-2*blobSignatureTTL))
+
+	if err := v.Delete(TestHash); err != nil {
+		t.Error(err)
+	}
+	if _, err := v.Get(TestHash); err == nil || !os.IsNotExist(err) {
+		t.Errorf("os.IsNotExist(%v) should have been true", err)
+	}
+}
+
+// Calling Delete() for a block that does not exist should result in error.
+// Test should pass for both writable and read-only volumes
+func testDeleteNoSuchBlock(t *testing.T, factory TestableVolumeFactory) {
+	v := factory(t)
+	defer v.Teardown()
+
+	if err := v.Delete(TestHash2); err == nil {
+		t.Errorf("Expected error when attempting to delete a non-existing block")
+	}
+}
+
+// Invoke Status and verify that VolumeStatus is returned
+// Test should pass for both writable and read-only volumes
+func testStatus(t *testing.T, factory TestableVolumeFactory) {
+	v := factory(t)
+	defer v.Teardown()
+
+	// Get node status and make a basic sanity check.
+	status := v.Status()
+	if status.DeviceNum == 0 {
+		t.Errorf("uninitialized device_num in %v", status)
+	}
+
+	if status.BytesFree == 0 {
+		t.Errorf("uninitialized bytes_free in %v", status)
+	}
+
+	if status.BytesUsed == 0 {
+		t.Errorf("uninitialized bytes_used in %v", status)
+	}
+}
+
+// Invoke String for the volume; expect non-empty result
+// Test should pass for both writable and read-only volumes
+func testString(t *testing.T, factory TestableVolumeFactory) {
+	v := factory(t)
+	defer v.Teardown()
 
-	if err := v.Delete(TEST_HASH); err != nil {
+	if id := v.String(); len(id) == 0 {
+		t.Error("Got empty string for v.String()")
+	}
+}
+
+// Putting, updating, touching, and deleting blocks from a read-only volume result in error.
+// Test is intended for only read-only volumes
+func testUpdateReadOnly(t *testing.T, factory TestableVolumeFactory) {
+	v := factory(t)
+	defer v.Teardown()
+
+	if v.Writable() == true {
+		return
+	}
+
+	v.PutRaw(TestHash, TestBlock)
+
+	// Get from read-only volume should succeed
+	_, err := v.Get(TestHash)
+	if err != nil {
+		t.Errorf("got err %v, expected nil", err)
+	}
+
+	// Put a new block to read-only volume should result in error
+	err = v.Put(TestHash2, TestBlock2)
+	if err == nil {
+		t.Errorf("Expected error when putting block in a read-only volume")
+	}
+	_, err = v.Get(TestHash2)
+	if err == nil {
+		t.Errorf("Expected error when getting block whose put in read-only volume failed")
+	}
+
+	// Touch a block in read-only volume should result in error
+	err = v.Touch(TestHash)
+	if err == nil {
+		t.Errorf("Expected error when touching block in a read-only volume")
+	}
+
+	// Delete a block from a read-only volume should result in error
+	err = v.Delete(TestHash)
+	if err == nil {
+		t.Errorf("Expected error when deleting block from a read-only volume")
+	}
+
+	// Overwriting an existing block in read-only volume should result in error
+	err = v.Put(TestHash, TestBlock)
+	if err == nil {
+		t.Errorf("Expected error when putting block in a read-only volume")
+	}
+}
+
+// Launch concurrent Gets
+// Test should pass for both writable and read-only volumes
+func testGetConcurrent(t *testing.T, factory TestableVolumeFactory) {
+	v := factory(t)
+	defer v.Teardown()
+
+	v.PutRaw(TestHash, TestBlock)
+	v.PutRaw(TestHash2, TestBlock2)
+	v.PutRaw(TestHash3, TestBlock3)
+
+	sem := make(chan int)
+	go func(sem chan int) {
+		buf, err := v.Get(TestHash)
+		if err != nil {
+			t.Errorf("err1: %v", err)
+		}
+		bufs.Put(buf)
+		if bytes.Compare(buf, TestBlock) != 0 {
+			t.Errorf("buf should be %s, is %s", string(TestBlock), string(buf))
+		}
+		sem <- 1
+	}(sem)
+
+	go func(sem chan int) {
+		buf, err := v.Get(TestHash2)
+		if err != nil {
+			t.Errorf("err2: %v", err)
+		}
+		bufs.Put(buf)
+		if bytes.Compare(buf, TestBlock2) != 0 {
+			t.Errorf("buf should be %s, is %s", string(TestBlock2), string(buf))
+		}
+		sem <- 1
+	}(sem)
+
+	go func(sem chan int) {
+		buf, err := v.Get(TestHash3)
+		if err != nil {
+			t.Errorf("err3: %v", err)
+		}
+		bufs.Put(buf)
+		if bytes.Compare(buf, TestBlock3) != 0 {
+			t.Errorf("buf should be %s, is %s", string(TestBlock3), string(buf))
+		}
+		sem <- 1
+	}(sem)
+
+	// Wait for all goroutines to finish
+	for done := 0; done < 3; {
+		done += <-sem
+	}
+}
+
+// Launch concurrent Puts
+// Test is intended for only writable volumes
+func testPutConcurrent(t *testing.T, factory TestableVolumeFactory) {
+	v := factory(t)
+	defer v.Teardown()
+
+	if v.Writable() == false {
+		return
+	}
+
+	sem := make(chan int)
+	go func(sem chan int) {
+		err := v.Put(TestHash, TestBlock)
+		if err != nil {
+			t.Errorf("err1: %v", err)
+		}
+		sem <- 1
+	}(sem)
+
+	go func(sem chan int) {
+		err := v.Put(TestHash2, TestBlock2)
+		if err != nil {
+			t.Errorf("err2: %v", err)
+		}
+		sem <- 1
+	}(sem)
+
+	go func(sem chan int) {
+		err := v.Put(TestHash3, TestBlock3)
+		if err != nil {
+			t.Errorf("err3: %v", err)
+		}
+		sem <- 1
+	}(sem)
+
+	// Wait for all goroutines to finish
+	for done := 0; done < 3; {
+		done += <-sem
+	}
+
+	// Double check that we actually wrote the blocks we expected to write.
+	buf, err := v.Get(TestHash)
+	if err != nil {
+		t.Errorf("Get #1: %v", err)
+	}
+	bufs.Put(buf)
+	if bytes.Compare(buf, TestBlock) != 0 {
+		t.Errorf("Get #1: expected %s, got %s", string(TestBlock), string(buf))
+	}
+
+	buf, err = v.Get(TestHash2)
+	if err != nil {
+		t.Errorf("Get #2: %v", err)
+	}
+	bufs.Put(buf)
+	if bytes.Compare(buf, TestBlock2) != 0 {
+		t.Errorf("Get #2: expected %s, got %s", string(TestBlock2), string(buf))
+	}
+
+	buf, err = v.Get(TestHash3)
+	if err != nil {
+		t.Errorf("Get #3: %v", err)
+	}
+	bufs.Put(buf)
+	if bytes.Compare(buf, TestBlock3) != 0 {
+		t.Errorf("Get #3: expected %s, got %s", string(TestBlock3), string(buf))
+	}
+}
+
+// Write and read back a full size block
+func testPutFullBlock(t *testing.T, factory TestableVolumeFactory) {
+	v := factory(t)
+	defer v.Teardown()
+
+	if !v.Writable() {
+		return
+	}
+
+	wdata := make([]byte, BlockSize)
+	wdata[0] = 'a'
+	wdata[BlockSize-1] = 'z'
+	hash := fmt.Sprintf("%x", md5.Sum(wdata))
+	err := v.Put(hash, wdata)
+	if err != nil {
+		t.Fatal(err)
+	}
+	rdata, err := v.Get(hash)
+	if err != nil {
 		t.Error(err)
+	} else {
+		defer bufs.Put(rdata)
 	}
-	if _, err := v.Get(TEST_HASH); err == nil || !os.IsNotExist(err) {
-		t.Errorf("os.IsNotExist(%v) should have been true", err.Error())
+	if bytes.Compare(rdata, wdata) != 0 {
+		t.Error("rdata != wdata")
 	}
 }