packer: add mock implementations and more template tests

common/command/template_test.go

 package command
 
 import (
+	"github.com/mitchellh/packer/packer"
 	"testing"
 )
 
+func testTemplate() (*packer.Template, *packer.ComponentFinder) {
+	tplData := `{
+	"builders": [
+	{
+		"type": "foo"
+	},
+	{
+		"type": "bar"
+	}
+	]
+}`
+
+	tpl, err := packer.ParseTemplate([]byte(tplData))
+	if err != nil {
+		panic(err)
+	}
+
+	cf := &packer.ComponentFinder{
+		Builder: func(string) (packer.Builder, error) { return new(packer.MockBuilder), nil },
+	}
+
+	return tpl, cf
+}
+
+func TestBuildOptionsBuilds(t *testing.T) {
+	opts := new(BuildOptions)
+	bs, err := opts.Builds(testTemplate())
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	if len(bs) != 2 {
+		t.Fatalf("bad: %d", len(bs))
+	}
+}
+
 func TestBuildOptionsValidate(t *testing.T) {
 	bf := new(BuildOptions)
 

packer/artifact_mock.go

+package packer
+
+// MockArtifact is an implementation of Artifact that can be used for tests.
+type MockArtifact struct {
+	IdValue       string
+	DestroyCalled bool
+}
+
+func (*MockArtifact) BuilderId() string {
+	return "bid"
+}
+
+func (*MockArtifact) Files() []string {
+	return []string{"a", "b"}
+}
+
+func (a *MockArtifact) Id() string {
+	id := a.IdValue
+	if id == "" {
+		id = "id"
+	}
+
+	return id
+}
+
+func (*MockArtifact) String() string {
+	return "string"
+}
+
+func (a *MockArtifact) Destroy() error {
+	a.DestroyCalled = true
+	return nil
+}

packer/builder_mock.go

+package packer
+
+// MockBuilder is an implementation of Builder that can be used for tests.
+// You can set some fake return values and you can keep track of what
+// methods were called on the builder. It is fairly basic.
+type MockBuilder struct {
+	ArtifactId string
+
+	PrepareCalled bool
+	PrepareConfig []interface{}
+	RunCalled     bool
+	RunCache      Cache
+	RunHook       Hook
+	RunUi         Ui
+	CancelCalled  bool
+}
+
+func (tb *MockBuilder) Prepare(config ...interface{}) error {
+	tb.PrepareCalled = true
+	tb.PrepareConfig = config
+	return nil
+}
+
+func (tb *MockBuilder) Run(ui Ui, h Hook, c Cache) (Artifact, error) {
+	tb.RunCalled = true
+	tb.RunHook = h
+	tb.RunUi = ui
+	tb.RunCache = c
+	return &MockArtifact{
+		IdValue: tb.ArtifactId,
+	}, nil
+}
+
+func (tb *MockBuilder) Cancel() {
+	tb.CancelCalled = true
+}