add golint's package name MixedCaps rule as in 83fdc39ff7/lint.go (L561-L563) (#797)

rule/var-naming.go

@@ -4,12 +4,15 @@ import (
 	"fmt"
 	"go/ast"
 	"go/token"
+	"regexp"
 	"strings"
 	"sync"
 
 	"github.com/mgechev/revive/lint"
 )
 
+var anyCapsRE = regexp.MustCompile(`[A-Z]`)
+
 // VarNamingRule lints given else constructs.
 type VarNamingRule struct {
 	configured bool
@@ -60,6 +63,14 @@ func (r *VarNamingRule) Apply(file *lint.File, arguments lint.Arguments) []lint.
 			Category:   "naming",
 		})
 	}
+	if anyCapsRE.MatchString(walker.fileAst.Name.Name) {
+		walker.onFailure(lint.Failure{
+			Failure:    fmt.Sprintf("don't use MixedCaps in package name; %s should be %s", walker.fileAst.Name.Name, strings.ToLower(walker.fileAst.Name.Name)),
+			Confidence: 1,
+			Node:       walker.fileAst.Name,
+			Category:   "naming",
+		})
+	}
 
 	ast.Walk(&walker, fileAst)
 

testdata/golint/pkg-caps.go

@@ -0,0 +1,4 @@
+// MixedCaps package name
+
+// Package PkgName ...
+package PkgName // MATCH /don't use MixedCaps in package name; PkgName should be pkgname/