mstate: add tests for ops w.r.t. life cycle

mstate/life_test.go

Index: mstate/life_test.go
=== modified file 'mstate/life_test.go'
--- mstate/life_test.go	2012-08-29 10:05:26 +0000
+++ mstate/life_test.go	2012-09-18 18:41:49 +0000
@@ -200,3 +200,40 @@
 		}
 	}
 }
+
+const (
+	notAliveErr = ".*: not found or not alive"
+	noErr       = ""
+)
+
+type lifer interface {
+	Die() error
+	Kill() error
+	Life() state.Life
+}
+
+func runLifeChecks(c *C, obj lifer, expectErr string, checks []func() error) {
+	for i, check := range checks {
+		c.Logf("check %d when %v", i, obj.Life())
+		err := check()
+		if expectErr == noErr {
+			c.Assert(err, IsNil)
+		} else {
+			c.Assert(err, ErrorMatches, expectErr)
+		}
+	}
+}
+
+// testWhenDying sets obj to Dying and Dead in turn, and asserts
+// that the errors from the given checks match aliveErr, dyingErr and deadErr
+// in each respective life state.
+func testWhenDying(c *C, obj lifer, dyingErr, deadErr string, checks ...func() error) {
+	c.Logf("checking life of %v (%T)", obj, obj)
+	runLifeChecks(c, obj, noErr, checks)
+	err := obj.Kill()
+	c.Assert(err, IsNil)
+	runLifeChecks(c, obj, dyingErr, checks)
+	err = obj.Die()
+	c.Assert(err, IsNil)
+	runLifeChecks(c, obj, deadErr, checks)
+}