improve Validate & test

typewriters/container/container.go

@@ -30,10 +30,28 @@ func (c *ContainerWriter) Name() string {
 
 func (c *ContainerWriter) Validate(t typewriter.Type) (bool, error) {
 	tag, found, err := t.Tags.ByName("containers")
-	if found && err == nil {
-		c.tagsByType[t.String()] = tag
+
+	if !found || err != nil {
+		return false, err
+	}
+
+	// must include at least one item that we recognize
+	any := false
+	for _, item := range tag.Items {
+		any = any || containerTemplates.Contains(item)
+		if any {
+			// found one, move on
+			break
+		}
 	}
-	return found, err
+
+	if !any {
+		// not an error, but irrelevant
+		return false, nil
+	}
+
+	c.tagsByType[t.String()] = tag
+	return true, nil
 }
 
 func (c *ContainerWriter) WriteHeader(w io.Writer, t typewriter.Type) {

typewriters/container/container_test.go

@@ -0,0 +1,71 @@
+package container
+
+import (
+	"testing"
+
+	"github.com/clipperhouse/gen/typewriter"
+)
+
+func TestValidate(t *testing.T) {
+	g := NewContainerWriter()
+
+	pkg := typewriter.NewPackage("dummy", "SomePackage")
+
+	typ := typewriter.Type{
+		Package: pkg,
+		Name:    "SomeType",
+		Tags:    typewriter.Tags{},
+	}
+
+	write, err := g.Validate(typ)
+
+	if write {
+		t.Errorf("no 'containers' tag should not write")
+	}
+
+	if err != nil {
+		t.Error(err)
+	}
+
+	typ2 := typewriter.Type{
+		Package: pkg,
+		Name:    "SomeType2",
+		Tags: typewriter.Tags{
+			typewriter.Tag{
+				Name:  "containers",
+				Items: []string{},
+			},
+		},
+	}
+
+	write2, err2 := g.Validate(typ2)
+
+	if write2 {
+		t.Errorf("empty 'containers' tag should not write")
+	}
+
+	if err2 != nil {
+		t.Error(err)
+	}
+
+	typ3 := typewriter.Type{
+		Package: pkg,
+		Name:    "SomeType3",
+		Tags: typewriter.Tags{
+			typewriter.Tag{
+				Name:  "containers",
+				Items: []string{"List", "Foo"},
+			},
+		},
+	}
+
+	write3, err3 := g.Validate(typ3)
+
+	if !write3 {
+		t.Errorf("'containers' tag with List should write (and ignore others)")
+	}
+
+	if err3 != nil {
+		t.Error(err)
+	}
+}