Very rough code that can helm install

The recommended way to test code that uses exec.Cmd involves setting up
a real exec.Cmd that invokes `go test` with additional arguments that
fire off a specially-constructed test that behaves the way the mocked-
out script would be expected to do. It's a sensible way to test exec.Cmd
itself, but for code that merely invokes it, I think it makes more sense
to use actual mocks.

internal/run/install_test.go

@@ -0,0 +1,20 @@
+package run
+
+import (
+	"github.com/golang/mock/gomock"
+	"testing"
+)
+
+func TestInstall(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	defer ctrl.Finish()
+
+	cmd := NewMockcmd(ctrl)
+	cmd.EXPECT().
+		Args(gomock.Eq([]string{"install", "arg1", "arg2"}))
+	cmd.EXPECT().
+		Run().
+		Times(1)
+
+	install(cmd, []string{"arg1", "arg2"})
+}