Handle container links

Ensures that linked containers are restarted if any of their
dependencies are restarted -- and makes sure that everything happens in
the correct order.

docker/util_test.go

@@ -0,0 +1,65 @@
+package docker
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSliceEqual_True(t *testing.T) {
+	s1 := []string{"a", "b", "c"}
+	s2 := []string{"a", "b", "c"}
+
+	result := sliceEqual(s1, s2)
+
+	assert.True(t, result)
+}
+
+func TestSliceEqual_DifferentLengths(t *testing.T) {
+	s1 := []string{"a", "b", "c"}
+	s2 := []string{"a", "b", "c", "d"}
+
+	result := sliceEqual(s1, s2)
+
+	assert.False(t, result)
+}
+
+func TestSliceEqual_DifferentContents(t *testing.T) {
+	s1 := []string{"a", "b", "c"}
+	s2 := []string{"a", "b", "d"}
+
+	result := sliceEqual(s1, s2)
+
+	assert.False(t, result)
+}
+
+func TestSliceSubtract(t *testing.T) {
+	a1 := []string{"a", "b", "c"}
+	a2 := []string{"a", "c"}
+
+	result := sliceSubtract(a1, a2)
+	assert.Equal(t, []string{"b"}, result)
+	assert.Equal(t, []string{"a", "b", "c"}, a1)
+	assert.Equal(t, []string{"a", "c"}, a2)
+}
+
+func TestStringMapSubtract(t *testing.T) {
+	m1 := map[string]string{"a": "a", "b": "b", "c": "sea"}
+	m2 := map[string]string{"a": "a", "c": "c"}
+
+	result := stringMapSubtract(m1, m2)
+	assert.Equal(t, map[string]string{"b": "b", "c": "sea"}, result)
+	assert.Equal(t, map[string]string{"a": "a", "b": "b", "c": "sea"}, m1)
+	assert.Equal(t, map[string]string{"a": "a", "c": "c"}, m2)
+}
+
+func TestStructMapSubtract(t *testing.T) {
+	x := struct{}{}
+	m1 := map[string]struct{}{"a": x, "b": x, "c": x}
+	m2 := map[string]struct{}{"a": x, "c": x}
+
+	result := structMapSubtract(m1, m2)
+	assert.Equal(t, map[string]struct{}{"b": x}, result)
+	assert.Equal(t, map[string]struct{}{"a": x, "b": x, "c": x}, m1)
+	assert.Equal(t, map[string]struct{}{"a": x, "c": x}, m2)
+}