diff --git a/raft/log_unstable_test.go b/raft/log_unstable_test.go
new file mode 100644
index 000000000..97685892c
--- /dev/null
+++ b/raft/log_unstable_test.go
@@ -0,0 +1,189 @@
+/*
+   Copyright 2014 CoreOS, 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 raft
+
+import (
+	"testing"
+
+	pb "github.com/coreos/etcd/raft/raftpb"
+)
+
+func TestUnstableMaybeFirstIndex(t *testing.T) {
+	tests := []struct {
+		entries []pb.Entry
+		offset  uint64
+		snap    *pb.Snapshot
+
+		wok    bool
+		windex uint64
+	}{
+		// no snapshot
+		{
+			[]pb.Entry{{Index: 5, Term: 1}}, 5, nil,
+			false, 0,
+		},
+		{
+			[]pb.Entry{}, 0, nil,
+			false, 0,
+		},
+		// has snapshot
+		{
+			[]pb.Entry{{Index: 5, Term: 1}}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
+			true, 5,
+		},
+		{
+			[]pb.Entry{}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
+			true, 5,
+		},
+	}
+
+	for i, tt := range tests {
+		u := unstable{
+			entries:  tt.entries,
+			offset:   tt.offset,
+			snapshot: tt.snap,
+		}
+		index, ok := u.maybeFirstIndex()
+		if ok != tt.wok {
+			t.Errorf("#%d: ok = %t, want %t", i, ok, tt.wok)
+		}
+		if index != tt.windex {
+			t.Errorf("#%d: index = %d, want %d", i, index, tt.windex)
+		}
+	}
+}
+
+func TestMaybeLastIndex(t *testing.T) {
+	tests := []struct {
+		entries []pb.Entry
+		offset  uint64
+		snap    *pb.Snapshot
+
+		wok    bool
+		windex uint64
+	}{
+		// last in entries
+		{
+			[]pb.Entry{{Index: 5, Term: 1}}, 5, nil,
+			true, 5,
+		},
+		{
+			[]pb.Entry{{Index: 5, Term: 1}}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
+			true, 5,
+		},
+		// last in snapshot
+		{
+			[]pb.Entry{}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
+			true, 4,
+		},
+		// empty unstable
+		{
+			[]pb.Entry{}, 0, nil,
+			false, 0,
+		},
+	}
+
+	for i, tt := range tests {
+		u := unstable{
+			entries:  tt.entries,
+			offset:   tt.offset,
+			snapshot: tt.snap,
+		}
+		index, ok := u.maybeLastIndex()
+		if ok != tt.wok {
+			t.Errorf("#%d: ok = %t, want %t", i, ok, tt.wok)
+		}
+		if index != tt.windex {
+			t.Errorf("#%d: index = %d, want %d", i, index, tt.windex)
+		}
+	}
+}
+
+func TestUnstableMaybeTerm(t *testing.T) {
+	tests := []struct {
+		entries []pb.Entry
+		offset  uint64
+		snap    *pb.Snapshot
+		index   uint64
+
+		wok   bool
+		wterm uint64
+	}{
+		// term from entries
+		{
+			[]pb.Entry{{Index: 5, Term: 1}}, 5, nil,
+			5,
+			true, 1,
+		},
+		{
+			[]pb.Entry{{Index: 5, Term: 1}}, 5, nil,
+			6,
+			false, 0,
+		},
+		{
+			[]pb.Entry{{Index: 5, Term: 1}}, 5, nil,
+			4,
+			false, 0,
+		},
+		{
+			[]pb.Entry{{Index: 5, Term: 1}}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
+			5,
+			true, 1,
+		},
+		{
+			[]pb.Entry{{Index: 5, Term: 1}}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
+			6,
+			false, 0,
+		},
+		// term from snapshot
+		{
+			[]pb.Entry{{Index: 5, Term: 1}}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
+			4,
+			true, 1,
+		},
+		{
+			[]pb.Entry{}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
+			5,
+			false, 0,
+		},
+		{
+			[]pb.Entry{}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
+			4,
+			true, 1,
+		},
+		{
+			[]pb.Entry{}, 0, nil,
+			5,
+			false, 0,
+		},
+	}
+
+	for i, tt := range tests {
+		u := unstable{
+			entries:  tt.entries,
+			offset:   tt.offset,
+			snapshot: tt.snap,
+		}
+		term, ok := u.maybeTerm(tt.index)
+		if ok != tt.wok {
+			t.Errorf("#%d: ok = %t, want %t", i, ok, tt.wok)
+		}
+		if term != tt.wterm {
+			t.Errorf("#%d: term = %d, want %d", i, term, tt.wterm)
+		}
+	}
+}