Include LevelDB fixture generators for curator.

This will help reduce common boilerplate for our test process
with respect to LevelDB-related things.

storage/raw/leveldb/test/fixtures.go

@@ -0,0 +1,121 @@
+// Copyright 2013 Prometheus Team
+// 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 test
+
+import (
+	"github.com/prometheus/prometheus/coding"
+	"github.com/prometheus/prometheus/storage/raw"
+	"github.com/prometheus/prometheus/storage/raw/leveldb"
+	"github.com/prometheus/prometheus/utility/test"
+)
+
+const (
+	cacheCapacity             = 0
+	bitsPerBloomFilterEncoded = 0
+)
+
+type (
+	// Pair models a prospective (key, value) double that will be committed to
+	// a database.
+	Pair interface {
+		Get() (key, value coding.Encoder)
+	}
+
+	// Pairs models a list of Pair for disk committing.
+	Pairs []Pair
+
+	// Preparer readies a LevelDB store for a given raw state given the fixtures
+	// definitions passed into it.
+	Preparer interface {
+		// Prepare furnishes the database and returns its path along with any
+		// encountered anomalies.
+		Prepare(namespace string, f FixtureFactory) test.TemporaryDirectory
+	}
+
+	FixtureFactory interface {
+		// HasNext indicates whether the FixtureFactory has more pending fixture
+		// data to build.
+		HasNext() (has bool)
+		// Next emits the next (key, value) double for storage.
+		Next() (key coding.Encoder, value coding.Encoder)
+	}
+
+	preparer struct {
+		tester test.Tester
+	}
+
+	cassetteFactory struct {
+		index int
+		count int
+		pairs Pairs
+	}
+)
+
+func (p preparer) Prepare(n string, f FixtureFactory) (t test.TemporaryDirectory) {
+	t = test.NewTemporaryDirectory(n, p.tester)
+
+	var (
+		persistence raw.Persistence
+		err         error
+	)
+
+	persistence, err = leveldb.NewLevelDBPersistence(t.Path(), cacheCapacity, bitsPerBloomFilterEncoded)
+	if err != nil {
+		defer t.Close()
+		p.tester.Fatal(err)
+	}
+
+	for f.HasNext() {
+		var (
+			key   coding.Encoder
+			value coding.Encoder
+		)
+
+		key, value = f.Next()
+
+		err = persistence.Put(key, value)
+		if err != nil {
+			defer t.Close()
+			p.tester.Fatal(err)
+		}
+	}
+
+	return
+}
+
+func (f cassetteFactory) HasNext() bool {
+	return f.index < f.count
+}
+
+func (f *cassetteFactory) Next() (key, value coding.Encoder) {
+	key, value = f.pairs[f.index].Get()
+
+	f.index++
+
+	return
+}
+
+// NewPreparer creates a new Preparer for use in testing scenarios.
+func NewPreparer(t test.Tester) Preparer {
+	return preparer{t}
+}
+
+// NewCassetteFactory builds a new FixtureFactory that uses Pairs as the basis
+// for generated fixture data.
+func NewCassetteFactory(pairs Pairs) FixtureFactory {
+	return &cassetteFactory{
+		pairs: pairs,
+		count: len(pairs),
+	}
+}

utility/test/directory.go

@@ -28,33 +28,35 @@ const (
 	NilCloser = nilCloser(true)
 )
 
-type Closer interface {
-	// Close reaps the underlying directory and its children.  The directory
-	// could be deleted by its users already.
-	Close()
-}
+type (
+	Closer interface {
+		// Close reaps the underlying directory and its children.  The directory
+		// could be deleted by its users already.
+		Close()
+	}
 
-type nilCloser bool
+	nilCloser bool
+
+	// TemporaryDirectory models a closeable path for transient POSIX disk
+	// activities.
+	TemporaryDirectory interface {
+		Closer
+
+		// Path returns the underlying path for access.
+		Path() string
+	}
+
+	// temporaryDirectory is kept as a private type due to private fields and
+	// their interactions.
+	temporaryDirectory struct {
+		path   string
+		tester Tester
+	}
+)
 
 func (c nilCloser) Close() {
 }
 
-// TemporaryDirectory models a closeable path for transient POSIX disk
-// activities.
-type TemporaryDirectory interface {
-	Closer
-
-	// Path returns the underlying path for access.
-	Path() string
-}
-
-// temporaryDirectory is kept as a private type due to private fields and their
-// interactions.
-type temporaryDirectory struct {
-	path   string
-	tester Tester
-}
-
 func (t temporaryDirectory) Close() {
 	err := os.RemoveAll(t.path)
 	if err != nil {