defined env type

the env type represents a test environment. This was added as an
intermediate container that could store the saved fields of tests after
they're run, so that future tests could load them. Previously a test
could only get the attributes of the test that immediately preceded it.
This change allows tests to load attributes further back in the history.

tea/env.go

@@ -0,0 +1,73 @@
+package tea
+
+import (
+	"fmt"
+	"reflect"
+)
+
+type env struct {
+	key    string
+	value  interface{}
+	parent *env
+}
+
+func mkenv(test Test) *env {
+	var e *env
+	return e.save(test)
+}
+
+// save looks at the Test t and saves the values of its fields marked with a
+// save tag
+func (e *env) save(test Test) *env {
+	V := reflect.ValueOf(test)
+	if V.Type().Kind() == reflect.Ptr {
+		V = V.Elem()
+	}
+	T := V.Type()
+
+	for i := 0; i < T.NumField(); i++ {
+		f := T.Field(i)
+		if !isSaveField(f) {
+			continue
+		}
+
+		fv := V.Field(i)
+		e = &env{
+			key:    f.Name,
+			value:  fv.Interface(),
+			parent: e,
+		}
+	}
+
+	return e
+}
+
+func (e *env) load(dest Test) error {
+	destV := reflect.ValueOf(dest).Elem()
+	destT := destV.Type()
+
+	for i := 0; i < destT.NumField(); i++ {
+		f := destT.Field(i)
+		if !isLoadField(f) {
+			continue
+		}
+		fv := destV.Field(i)
+
+		set := false
+		for e := e; e != nil; e = e.parent {
+			if e.key == f.Name {
+				ev := reflect.ValueOf(e.value)
+				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)
+		}
+	}
+	return nil
+}

tea/env_test.go

@@ -0,0 +1,70 @@
+package tea
+
+import (
+	"testing"
+)
+
+func TestSave(t *testing.T) {
+	type saveFoo struct {
+		empty
+		Foo int `tea:"save"`
+		Bar string
+	}
+
+	type loadFoo struct {
+		empty
+		Foo int `tea:"load"`
+		Bar string
+	}
+
+	t.Run("empty begets nil", func(t *testing.T) {
+		e := mkenv(new(empty))
+		if e != nil {
+			t.Errorf("saw unexpected env value looking for nil: %v", e)
+		}
+	})
+
+	t.Run("unexported fields are ignored", func(t *testing.T) {
+		type test struct {
+			empty
+			foo int `tea:"save"`
+		}
+
+		if e := mkenv(test{foo: 5}); e != nil {
+			t.Errorf("saw unexpected env value looking for nil: %v", e)
+		}
+	})
+
+	t.Run("save an int", func(t *testing.T) {
+		e := mkenv(&saveFoo{Foo: 5})
+		if e == nil {
+			t.Fatalf("saw nil env when expecting a valid env")
+		}
+
+		if e.key != "Foo" {
+			t.Errorf("expected key %q but saw %q instead", "Foo", e.key)
+		}
+
+		if e.value != 5 {
+			t.Errorf("expected value %v but saw %v instead", 5, e.value)
+		}
+	})
+
+	t.Run("load an int", func(t *testing.T) {
+		e := mkenv(&saveFoo{Foo: 5})
+		test := new(loadFoo)
+
+		e.load(test)
+		if test.Foo != 5 {
+			t.Errorf("expected value %v but saw %v instead", 5, test.Foo)
+		}
+	})
+
+	t.Run("loads can fail", func(t *testing.T) {
+		e := mkenv(new(empty))
+		test := new(loadFoo)
+		if err := e.load(test); err == nil {
+			t.Errorf("expected a load error but did not see one")
+		}
+	})
+}

tea/test.go

@@ -18,3 +18,10 @@ type failure struct {
 }
 
 func (f failure) Run(t *testing.T) { t.Error(f.cause.Error()) }
+
+// empty is an empty test. It does nothing when run, it's just used as a
+// sentinel value to create notes in the test graph and for ... testing the tea
+// package itself.
+type empty struct{}
+
+func (e empty) Run(t *testing.T) {}

tea/tree.go

@@ -6,32 +6,63 @@ import (
 	"testing"
 )
 
-// Run runs a tree of tests, starting from its root.
+// Run runs a tree of tests. Tests will be run recursively starting at the
+// provided node and descending to all of its children. All of its parent nodes
+// will also be run since they are prerequisites, but none of its sibling node
+// will be executed.
 func Run(t *testing.T, tree *Tree) {
 	t.Run(tree.name, func(t *testing.T) {
-		test := setup(t, tree)
-		test.Run(t)
+		setup(t, tree)
 
-		for _, child := range tree.children {
-			if t.Failed() || t.Skipped() {
+		if t.Failed() || t.Skipped() {
+			for _, child := range tree.children {
 				skip(t, child)
-			} else {
-				Run(t, child)
 			}
+			return
+		}
+
+		for _, child := range tree.children {
+			Run(t, child)
 		}
 	})
 }
 
-func setup(t *testing.T, tree *Tree) Test {
-	test := clone(tree.test)
-	if tree.parent != nil {
-		p := setup(t, tree.parent)
-		p.Run(t)
-		test = merge(test, p)
+// setup runs all of the tests ancestor to the given tree, building up a
+// testing environment from their side-effects
+func setup(t *testing.T, tree *Tree) *env {
+	if tree == nil {
+		return nil
+	}
+
+	if tree.parent == nil {
+		test := clone(tree.test)
+		test.Run(t)
+		return mkenv(test)
 	}
-	return test
+
+	e := setup(t, tree.parent)
+	test := clone(tree.test)
+	e.load(test)
+	test.Run(t)
+	return e.save(test)
 }
 
+// setup runs all of the dependencies for a given test. All of the tests are
+// run in the same subtest (and therefore same goroutine).
+// func setup(t *testing.T, tree *Tree) Test {
+// 	// clone the user's values before doing anything, we don't want to pollute
+// 	// the planning tree.
+// 	test := clone(tree.test)
+//
+// 	if tree.parent != nil {
+// 		p := setup(t, tree.parent)
+// 		p.Run(t)
+// 		test = merge(test, p)
+// 	}
+//
+// 	return test
+// }
+
 func skip(t *testing.T, tree *Tree) {
 	t.Run(tree.name, func(t *testing.T) {
 		for _, child := range tree.children {
@@ -96,6 +127,10 @@ func merge(dest Test, src Test) Test {
 // isSaveField takes a struct field and checks its tags for a save tag,
 // indicating that the field's value should persist between tests
 func isSaveField(f reflect.StructField) bool {
+	// PkgPath is empty string when the identifier is unexported.
+	if f.PkgPath != "" {
+		return false
+	}
 	parts := strings.Split(f.Tag.Get("tea"), ",")
 	for _, part := range parts {
 		if part == "save" {
@@ -109,6 +144,10 @@ func isSaveField(f reflect.StructField) bool {
 // indicating that the field's value should be populated by a saved value from
 // a prior test in the chain.
 func isLoadField(f reflect.StructField) bool {
+	// PkgPath is empty string when the identifier is unexported.
+	if f.PkgPath != "" {
+		return false
+	}
 	parts := strings.Split(f.Tag.Get("tea"), ",")
 	for _, part := range parts {
 		if part == "load" {
@@ -118,6 +157,7 @@ func isLoadField(f reflect.StructField) bool {
 	return false
 }
 
+// parseName parses the name for a given test
 func parseName(test Test) string {
 	if s, ok := test.(interface{ String() string }); ok {
 		return s.String()

tea_test.go

@@ -9,6 +9,10 @@ import (
 	"./tea"
 )
 
+type empty struct{}
+
+func (e *empty) Run(t *testing.T) {}
+
 type testThingSetup struct {
 	Thing *Thing `tea:"save"`
 }
@@ -37,6 +41,7 @@ func (test setKey) String() string {
 func (test *setKey) Run(t *testing.T) {
 	t.Logf("[%s] running setKey key: %q value: %q", t.Name(), test.key, test.value)
 
+	// test.Thing is automatically propagated from the prior test by tea!
 	err := test.Thing.Set(test.key, test.value)
 	if !test.bad && err != nil {
 		t.Errorf("should be able to set %q=%q but saw error %v", test.key, test.value, err)
@@ -51,7 +56,8 @@ func TestThing(t *testing.T) {
 
 	root.Child(&setKey{key: "alice", value: "apple"})
 	root.Child(&setKey{key: "bob", value: "banana"})
-	root.Child(&setKey{key: "carol", value: "cherry"})
+	root.Child(new(empty)).Child(&setKey{key: "carol", value: "cherry"})
+	root.Child(&setKey{bad: true})
 
 	bob := root.Child(&setKey{key: "b ob", value: "banana"})
 	bob.Child(&setKey{key: "car-el", value: "cherry"})