env uses layers

doc.go

@@ -0,0 +1,7 @@
+/*
+
+	Package tea provides a tree structure for writing stateful tests, such that
+	child tests may utilize the side-effects of their ancestors.
+
+*/
+package tea

env.go

@@ -6,8 +6,7 @@ import (
 )
 
 type env struct {
-	key    string
+	data   map[string]interface{}
-	value  interface{}
 	parent *env
 }
 
@@ -17,7 +16,8 @@ func mkenv(test Test) *env {
 }
 
 // save looks at the Test t and saves the values of its fields marked with a
-// save tag
+// save tag. All of the fields for that tests are stored together as a data
+// layer.
 func (e *env) save(test Test) *env {
 	V := reflect.ValueOf(test)
 	if V.Type().Kind() == reflect.Ptr {
@@ -25,6 +25,7 @@ func (e *env) save(test Test) *env {
 	}
 	T := V.Type()
 
+	saved := make(map[string]interface{})
 	for i := 0; i < T.NumField(); i++ {
 		f := T.Field(i)
 		if !isSaveField(f) {
@@ -32,9 +33,11 @@ func (e *env) save(test Test) *env {
 		}
 
 		fv := V.Field(i)
-		e = &env{
+		saved[f.Name] = fv.Interface()
-			key:    f.Name,
+	}
-			value:  fv.Interface(),
+	if len(saved) > 0 {
+		return &env{
+			data:   saved,
 			parent: e,
 		}
 	}
@@ -55,15 +58,18 @@ func (e *env) load(dest Test) error {
 
 		set := false
 		for e := e; e != nil; e = e.parent {
-			if e.key == f.Name {
+			v, ok := e.data[f.Name]
-				ev := reflect.ValueOf(e.value)
+			if !ok {
+				continue
+			}
+
+			ev := reflect.ValueOf(v)
 			if ev.Type().AssignableTo(fv.Type()) {
 				set = true
 				fv.Set(ev)
 				break
 			}
 		}
-		}
 
 		if !set {
 			return fmt.Errorf("failed to set required field: %q", f.Name)

env_test.go

@@ -41,12 +41,13 @@ func TestSave(t *testing.T) {
 			t.Fatalf("saw nil env when expecting a valid env")
 		}
 
-		if e.key != "Foo" {
+		foo, ok := e.data["Foo"]
-			t.Errorf("expected key %q but saw %q instead", "Foo", e.key)
+		if !ok {
+			t.Errorf("expected field Foo to be saved but was not saved")
 		}
 
-		if e.value != 5 {
+		if foo != 5 {
-			t.Errorf("expected value %v but saw %v instead", 5, e.value)
+			t.Errorf("expected value %v but saw %v instead", 5, foo)
 		}
 	})
 

runner.go

@@ -1 +0,0 @@
-package tea