Add pkg/discovery for nodes discovery

Absorb Swarm's discovery package in order to provide a common node
discovery mechanism to be used by both Swarm and networking code.

Signed-off-by: Arnaud Porterie <arnaud.porterie@docker.com>

discovery/discovery_test.go

@@ -0,0 +1,120 @@
+package discovery
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNewEntry(t *testing.T) {
+	entry, err := NewEntry("127.0.0.1:2375")
+	assert.NoError(t, err)
+	assert.True(t, entry.Equals(&Entry{Host: "127.0.0.1", Port: "2375"}))
+	assert.Equal(t, entry.String(), "127.0.0.1:2375")
+
+	_, err = NewEntry("127.0.0.1")
+	assert.Error(t, err)
+}
+
+func TestParse(t *testing.T) {
+	scheme, uri := parse("127.0.0.1:2375")
+	assert.Equal(t, scheme, "nodes")
+	assert.Equal(t, uri, "127.0.0.1:2375")
+
+	scheme, uri = parse("localhost:2375")
+	assert.Equal(t, scheme, "nodes")
+	assert.Equal(t, uri, "localhost:2375")
+
+	scheme, uri = parse("scheme://127.0.0.1:2375")
+	assert.Equal(t, scheme, "scheme")
+	assert.Equal(t, uri, "127.0.0.1:2375")
+
+	scheme, uri = parse("scheme://localhost:2375")
+	assert.Equal(t, scheme, "scheme")
+	assert.Equal(t, uri, "localhost:2375")
+
+	scheme, uri = parse("")
+	assert.Equal(t, scheme, "nodes")
+	assert.Equal(t, uri, "")
+}
+
+func TestCreateEntries(t *testing.T) {
+	entries, err := CreateEntries(nil)
+	assert.Equal(t, entries, Entries{})
+	assert.NoError(t, err)
+
+	entries, err = CreateEntries([]string{"127.0.0.1:2375", "127.0.0.2:2375", ""})
+	assert.NoError(t, err)
+	expected := Entries{
+		&Entry{Host: "127.0.0.1", Port: "2375"},
+		&Entry{Host: "127.0.0.2", Port: "2375"},
+	}
+	assert.True(t, entries.Equals(expected))
+
+	_, err = CreateEntries([]string{"127.0.0.1", "127.0.0.2"})
+	assert.Error(t, err)
+}
+
+func TestContainsEntry(t *testing.T) {
+	entries, err := CreateEntries([]string{"127.0.0.1:2375", "127.0.0.2:2375", ""})
+	assert.NoError(t, err)
+	assert.True(t, entries.Contains(&Entry{Host: "127.0.0.1", Port: "2375"}))
+	assert.False(t, entries.Contains(&Entry{Host: "127.0.0.3", Port: "2375"}))
+}
+
+func TestEntriesEquality(t *testing.T) {
+	entries := Entries{
+		&Entry{Host: "127.0.0.1", Port: "2375"},
+		&Entry{Host: "127.0.0.2", Port: "2375"},
+	}
+
+	// Same
+	assert.True(t, entries.Equals(Entries{
+		&Entry{Host: "127.0.0.1", Port: "2375"},
+		&Entry{Host: "127.0.0.2", Port: "2375"},
+	}))
+
+	// Different size
+	assert.False(t, entries.Equals(Entries{
+		&Entry{Host: "127.0.0.1", Port: "2375"},
+		&Entry{Host: "127.0.0.2", Port: "2375"},
+		&Entry{Host: "127.0.0.3", Port: "2375"},
+	}))
+
+	// Different content
+	assert.False(t, entries.Equals(Entries{
+		&Entry{Host: "127.0.0.1", Port: "2375"},
+		&Entry{Host: "127.0.0.42", Port: "2375"},
+	}))
+}
+
+func TestEntriesDiff(t *testing.T) {
+	entry1 := &Entry{Host: "1.1.1.1", Port: "1111"}
+	entry2 := &Entry{Host: "2.2.2.2", Port: "2222"}
+	entry3 := &Entry{Host: "3.3.3.3", Port: "3333"}
+	entries := Entries{entry1, entry2}
+
+	// No diff
+	added, removed := entries.Diff(Entries{entry2, entry1})
+	assert.Empty(t, added)
+	assert.Empty(t, removed)
+
+	// Add
+	added, removed = entries.Diff(Entries{entry2, entry3, entry1})
+	assert.Len(t, added, 1)
+	assert.True(t, added.Contains(entry3))
+	assert.Empty(t, removed)
+
+	// Remove
+	added, removed = entries.Diff(Entries{entry2})
+	assert.Empty(t, added)
+	assert.Len(t, removed, 1)
+	assert.True(t, removed.Contains(entry1))
+
+	// Add and remove
+	added, removed = entries.Diff(Entries{entry1, entry3})
+	assert.Len(t, added, 1)
+	assert.True(t, added.Contains(entry3))
+	assert.Len(t, removed, 1)
+	assert.True(t, removed.Contains(entry2))
+}