diff --git a/git/refs.go b/git/refs.go
index 60212e56..38fbe119 100644
--- a/git/refs.go
+++ b/git/refs.go
@@ -94,8 +94,4 @@ func refCommitish(r *Ref) string {
 // copy of env
 type Env interface {
 	Get(key string) (val string, ok bool)
-	GetAll(key string) (vals []string)
-	Bool(key string, def bool) (val bool)
-	Int(key string, def int) (val int)
-	All() map[string][]string
 }
diff --git a/git/refs_test.go b/git/refs_test.go
new file mode 100644
index 00000000..951ec163
--- /dev/null
+++ b/git/refs_test.go
@@ -0,0 +1,83 @@
+package git
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRefUpdateDefault(t *testing.T) {
+	pushModes := []string{"simple", ""}
+	for _, pushMode := range pushModes {
+		env := newEnv(map[string][]string{
+			"push.default":       []string{pushMode},
+			"branch.left.remote": []string{"ignore"},
+			"branch.left.merge":  []string{"me"},
+		})
+
+		u := NewRefUpdate(env, "origin", ParseRef("refs/heads/left", ""), nil)
+		assert.Equal(t, "left", u.Right().Name, "pushmode=%q", pushMode)
+		assert.Equal(t, RefTypeLocalBranch, u.Right().Type, "pushmode=%q", pushMode)
+	}
+}
+
+func TestRefUpdateTrackedDefault(t *testing.T) {
+	pushModes := []string{"simple", "upstream", "tracking", ""}
+	for _, pushMode := range pushModes {
+		env := newEnv(map[string][]string{
+			"push.default":       []string{pushMode},
+			"branch.left.remote": []string{"origin"},
+			"branch.left.merge":  []string{"refs/heads/tracked"},
+		})
+
+		u := NewRefUpdate(env, "origin", ParseRef("refs/heads/left", ""), nil)
+		assert.Equal(t, "tracked", u.Right().Name, "pushmode=%s", pushMode)
+		assert.Equal(t, RefTypeLocalBranch, u.Right().Type, "pushmode=%q", pushMode)
+	}
+}
+
+func TestRefUpdateCurrentDefault(t *testing.T) {
+	env := newEnv(map[string][]string{
+		"push.default":       []string{"current"},
+		"branch.left.remote": []string{"origin"},
+		"branch.left.merge":  []string{"tracked"},
+	})
+
+	u := NewRefUpdate(env, "origin", ParseRef("refs/heads/left", ""), nil)
+	assert.Equal(t, "left", u.Right().Name)
+	assert.Equal(t, RefTypeLocalBranch, u.Right().Type)
+}
+
+func TestRefUpdateExplicitLeftAndRight(t *testing.T) {
+	u := NewRefUpdate(nil, "", ParseRef("refs/heads/left", "abc123"), ParseRef("refs/heads/right", "def456"))
+	assert.Equal(t, "left", u.Left().Name)
+	assert.Equal(t, "abc123", u.Left().Sha)
+	assert.Equal(t, "abc123", u.LeftCommitish())
+	assert.Equal(t, "right", u.Right().Name)
+	assert.Equal(t, "def456", u.Right().Sha)
+	assert.Equal(t, "def456", u.RightCommitish())
+
+	u = NewRefUpdate(nil, "", ParseRef("refs/heads/left", ""), ParseRef("refs/heads/right", ""))
+	assert.Equal(t, "left", u.Left().Name)
+	assert.Equal(t, "", u.Left().Sha)
+	assert.Equal(t, "left", u.LeftCommitish())
+	assert.Equal(t, "right", u.Right().Name)
+	assert.Equal(t, "", u.Right().Sha)
+	assert.Equal(t, "right", u.RightCommitish())
+}
+
+func newEnv(m map[string][]string) *mapEnv {
+	return &mapEnv{data: m}
+}
+
+type mapEnv struct {
+	data map[string][]string
+}
+
+func (m *mapEnv) Get(key string) (string, bool) {
+	vals, ok := m.data[key]
+	if ok && len(vals) > 0 {
+		return vals[0], true
+	}
+	return "", false
+}