Milo: Add step text for swarming task exceptions

appengine/cmd/milo/swarming/build_test.go

 // Copyright 2015 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package swarming
 
 import (
         "encoding/json"
         "flag"
         "fmt"
@@ skipping 27 matching lines @@
 func TestBuild(t *testing.T) {
         testCases := []struct {
                 input        string
                 expectations string
         }{
                 {"build-exception", "build-exception.json"},
                 {"build-patch-failure", "build-patch-failure.json"},
                 {"build-pending", "build-pending.json"},
                 {"build-running", "build-running.json"},
                 {"build-timeout", "build-timeout.json"},
+                {"build-canceled", "build-canceled.json"},
         }
 
         c := context.Background()
         c, _ = testclock.UseTime(c, time.Date(2016, time.March, 14, 11, 0, 0, 0, time.UTC))
 
         if *generate {
                 for _, tc := range testCases {
                         fmt.Printf("Generating expectations for %s\n", tc.input)
                         build, err := swarmingBuildImpl(c, "foo", "debug", tc.input)
                         if err != nil {
@@ skipping 15 matching lines @@
         Convey(`A test Environment`, t, func() {
                 for _, tc := range testCases {
                         Convey(fmt.Sprintf("Test Case: %s", tc.input), func() {
                                 build, err := swarmingBuildImpl(c, "foo", "debug", tc.input)
                                 So(err, ShouldBeNil)
                                 So(build, shouldMatchExpectationsFor, tc.expectations)
                         })
                 }
         })
 }