fix(tiller): set up Tiller environment correctly

And structure the tests better.

cmd/tiller/environment/environment.go

@@ -1,9 +1,14 @@
 package environment
 
 import (
+	"github.com/deis/tiller/pkg/engine"
 	"github.com/deis/tiller/pkg/hapi"
 )
 
+const GoTplEngine = "gotpl"
+
+var DefaultEngine = GoTplEngine
+
 // EngineYard maps engine names to engine implementations.
 type EngineYard map[string]Engine
 
@@ -12,6 +17,20 @@ func (y EngineYard) Get(k string) (Engine, bool) {
 	return e, ok
 }
 
+// Default returns the default template engine.
+//
+// The default is specified by DefaultEngine.
+//
+// If the default template engine cannot be found, this panics.
+func (y EngineYard) Default() Engine {
+	d, ok := y[DefaultEngine]
+	if !ok {
+		// This is a developer error!
+		panic("Default template engine does not exist")
+	}
+	return d
+}
+
 // Engine represents a template engine that can render templates.
 //
 // For some engines, "rendering" includes both compiling and executing. (Other
@@ -55,5 +74,9 @@ type Environment struct {
 
 // New returns an environment initialized with the defaults.
 func New() *Environment {
-	return &Environment{}
+	e := engine.New()
+	var ey EngineYard = map[string]Engine{GoTplEngine: e}
+	return &Environment{
+		EngineYard: ey,
+	}
 }

pkg/engine/engine_test.go

@@ -4,12 +4,8 @@ import (
 	"fmt"
 	"sync"
 	"testing"
-
-	"github.com/deis/tiller/cmd/tiller/environment"
 )
 
-var _ environment.Engine = &Engine{}
-
 func TestEngine(t *testing.T) {
 	e := New()