environs/config: make CA cert optional

cmd/juju/cmd_test.go

 package main
 
 import (
+        "io/ioutil"
         "os"
         "reflect"
 
         "launchpad.net/gnuflag"
         . "launchpad.net/gocheck"
         "launchpad.net/juju-core/cmd"
         "launchpad.net/juju-core/environs/dummy"
         "launchpad.net/juju-core/juju/testing"
 )
 
 type CmdSuite struct {
         testing.JujuConnSuite
+        home fakeHome
 }
 
 var _ = Suite(&CmdSuite{})
 
 var envConfig = `
 default:
     peckham
 environments:
     peckham:
         type: dummy
         state-server: false
         admin-secret: arble
         authorized-keys: i-am-a-key
     walthamstow:
         type: dummy
         state-server: false
         authorized-keys: i-am-a-key
     brokenenv:
         type: dummy
         broken: Bootstrap Destroy
         state-server: false
         authorized-keys: i-am-a-key
 `
 
 func (s *CmdSuite) SetUpTest(c *C) {
         s.JujuConnSuite.SetUpTest(c)
-        s.JujuConnSuite.WriteConfig(envConfig)
+        s.home = makeFakeHome(c, "peckham", "walthamstow", "brokenenv")
+        err := ioutil.WriteFile(homePath(".juju", "environments.yaml"), []byte(envConfig), 0666)
+        c.Assert(err, IsNil)
+}
+
+func (s *CmdSuite) TearDownTest(c *C) {
+        s.home.restore()
+        s.JujuConnSuite.TearDownTest(c)
 }
 
 func newFlagSet() *gnuflag.FlagSet {
         return gnuflag.NewFlagSet("", gnuflag.ContinueOnError)
 }
 
 // testInit checks that a command initialises correctly
 // with the given set of arguments.
 func testInit(c *C, com cmd.Command, args []string, errPat string) {
         err := com.Init(newFlagSet(), args)
@@ skipping 294 matching lines @@
 }
 
 func (*CmdSuite) TestRemoveUnitCommandInit(c *C) {
         // missing args
         _, err := initRemoveUnitCommand()
         c.Assert(err, ErrorMatches, "no service units specified")
         // not a unit
         _, err = initRemoveUnitCommand("seven/nine")
         c.Assert(err, ErrorMatches, "invalid service unit name: \"seven/nine\"")
 }