erasureReadFile and erasureCreateFile testcases. (#2229)

* unit-tests: Unit tests for erasureCreateFile and erasureReadFile.

* appendFile() should return errXLWriteQuorum.

* TestErasureReadFileOffsetLength() tests erasureReadFile() for different offset and lengths.

* Fix for the failure seen in the erasure read unit test case. Issue #2227

* Move common erasure setup code to newErasureTestSetup()

* Review fixes. Add few more test cases for erasureReadFile.

erasure-createfile_test.go

@@ -0,0 +1,97 @@
+/*
+ * Minio Cloud Storage, (C) 2016 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package main
+
+import (
+	"bytes"
+	"crypto/rand"
+	"testing"
+)
+
+// Simulates a faulty disk for AppendFile()
+type AppendDiskDown struct {
+	*posix
+}
+
+func (a AppendDiskDown) AppendFile(volume string, path string, buf []byte) error {
+	return errFaultyDisk
+}
+
+// Test erasureCreateFile()
+func TestErasureCreateFile(t *testing.T) {
+	// Initialize environment needed for the test.
+	dataBlocks := 7
+	parityBlocks := 7
+	blockSize := int64(blockSizeV1)
+	setup, err := newErasureTestSetup(dataBlocks, parityBlocks, blockSize)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	defer setup.Remove()
+
+	disks := setup.disks
+
+	// Prepare a slice of 1MB with random data.
+	data := make([]byte, 1*1024*1024)
+	_, err = rand.Read(data)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Test when all disks are up.
+	size, _, err := erasureCreateFile(disks, "testbucket", "testobject1", bytes.NewReader(data), blockSize, dataBlocks, parityBlocks, dataBlocks+1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if size != int64(len(data)) {
+		t.Errorf("erasureCreateFile returned %d, expected %d", size, len(data))
+	}
+
+	// 2 disks down.
+	disks[4] = AppendDiskDown{disks[4].(*posix)}
+	disks[5] = AppendDiskDown{disks[5].(*posix)}
+
+	// Test when two disks are down.
+	size, _, err = erasureCreateFile(disks, "testbucket", "testobject2", bytes.NewReader(data), blockSize, dataBlocks, parityBlocks, dataBlocks+1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if size != int64(len(data)) {
+		t.Errorf("erasureCreateFile returned %d, expected %d", size, len(data))
+	}
+
+	// 4 more disks down. 6 disks down in total.
+	disks[6] = AppendDiskDown{disks[6].(*posix)}
+	disks[7] = AppendDiskDown{disks[7].(*posix)}
+	disks[8] = AppendDiskDown{disks[8].(*posix)}
+	disks[9] = AppendDiskDown{disks[9].(*posix)}
+
+	size, _, err = erasureCreateFile(disks, "testbucket", "testobject3", bytes.NewReader(data), blockSize, dataBlocks, parityBlocks, dataBlocks+1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if size != int64(len(data)) {
+		t.Errorf("erasureCreateFile returned %d, expected %d", size, len(data))
+	}
+
+	// 1 more disk down. 7 disk down in total. Should return quorum error.
+	disks[10] = AppendDiskDown{disks[10].(*posix)}
+	size, _, err = erasureCreateFile(disks, "testbucket", "testobject4", bytes.NewReader(data), blockSize, dataBlocks, parityBlocks, dataBlocks+1)
+	if err != errXLWriteQuorum {
+		t.Error("Expected errXLWriteQuorum error")
+	}
+}