Introduce staticcheck static analysis

Staticcheck is a tool that is highly recommended by the Go tools
team, so let's give it a go.
https://staticcheck.io/

.travis.yml

@@ -8,4 +8,6 @@ go:
 env:
  - GO111MODULE=on
 
-script: go run github.com/onsi/ginkgo/ginkgo -r
+script:
+- go run honnef.co/go/tools/cmd/staticcheck ./...
+- go run github.com/onsi/ginkgo/ginkgo -r

catalog_test.go

@@ -222,7 +222,7 @@ var _ = Describe("Catalog", func() {
  Bullets: []string{"hello", "its me"},
  DisplayName: "name",
  AdditionalMetadata: map[string]interface{}{
- "foo": make(chan int, 0),
+ "foo": make(chan int),
  },
  }
  _, err := json.Marshal(metadata)

domain/apiresponses/failure_responses.go

@@ -1,7 +1,6 @@
 package apiresponses
 
 import (
- "errors"
  "fmt"
  "net/http"
 
@@ -64,7 +63,7 @@ func (f *FailureResponse) LoggerAction() string {
 // AppendErrorMessage returns an error with the message updated. All other properties are preserved.
 func (f *FailureResponse) AppendErrorMessage(msg string) *FailureResponse {
  return &FailureResponse{
- error: errors.New(fmt.Sprintf("%s %s", f.Error(), msg)),
+ error: fmt.Errorf("%s %s", f.Error(), msg),
  statusCode: f.statusCode,
  loggerAction: f.loggerAction,
  emptyResponse: f.emptyResponse,

domain/service_plan_metadata_test.go

@@ -80,7 +80,7 @@ var _ = Describe("ServicePlanMetadata", func() {
  Bullets: []string{"hello", "its me"},
  DisplayName: "name",
  AdditionalMetadata: map[string]interface{}{
- "foo": make(chan int, 0),
+ "foo": make(chan int),
  },
  }
  _, err := json.Marshal(metadata)

fakes/staticcheck.conf

@@ -0,0 +1 @@
+checks = []

staticcheck.conf

@@ -0,0 +1,4 @@
+# When adding staticcheck, we thought it was better to get it working with some checks disabled
+# rather than fixing all the problems in one go. Some problems cannot be fixed without making
+# breaking changes.
+checks = ["all", "-SA1019", "-ST1000", "-ST1003", "-ST1005", "-ST1012", "-ST1021", "-SA1029", "-ST1020"]

tools/tools.go

@@ -5,6 +5,7 @@ package tools
 import (
  _ "github.com/maxbrunsfeld/counterfeiter/v6"
  _ "github.com/onsi/ginkgo"
+ _ "honnef.co/go/tools/cmd/staticcheck"
 )
 
 // This file imports packages that are used when running go generate, or used