diff --git a/.gometalinter.json b/.gometalinter.json
deleted file mode 100644
index 3817a8b7..00000000
--- a/.gometalinter.json
+++ /dev/null
@@ -1,25 +0,0 @@
-{
-  "Vendor": true,
-  "Test": true,
-  "Sort": [
-    "path",
-    "line",
-    "column",
-    "linter",
-    "severity"
-  ],
-  "Cyclo": 12,
-  "Enable": [
-    "gotypex",
-    "varcheck",
-    "gotype",
-    "interfacer",
-    "misspell",
-    "ineffassign",
-    "golint",
-    "vet",
-    "gosimple"
-  ],
-  "Exclude": [],
-  "Deadline": "2m"
-}
diff --git a/README.md b/README.md
index 6e2b926f..528b1741 100644
--- a/README.md
+++ b/README.md
@@ -2,8 +2,9 @@
 
 Let's Encrypt client and ACME library written in Go
 
-[![GoDoc](https://godoc.org/github.com/xenolf/lego/acme?status.svg)](https://godoc.org/github.com/xenolf/lego/acme)
+[![GoDoc](https://godoc.org/github.com/xenolf/lego?status.svg)](https://godoc.org/github.com/xenolf/lego/acme)
 [![Build Status](https://travis-ci.org/xenolf/lego.svg?branch=master)](https://travis-ci.org/xenolf/lego)
+[![Docker Pulls](https://img.shields.io/docker/pulls/xenolf/lego.svg)](https://hub.docker.com/r/xenolf/lego/)
 [![Dev Chat](https://img.shields.io/badge/dev%20chat-gitter-blue.svg?label=dev+chat)](https://gitter.im/xenolf/lego)
 [![Beerpay](https://beerpay.io/xenolf/lego/badge.svg)](https://beerpay.io/xenolf/lego)
 
@@ -20,8 +21,7 @@ To install from source, just run:
 go get -u github.com/xenolf/lego
 ```
 
-To build lego inside a Docker container, just run
-
+To build lego inside a Docker container, just run:
 ```bash
 docker build -t lego .
 ```
diff --git a/platform/tester/env.go b/platform/tester/env.go
index b42da278..943842db 100644
--- a/platform/tester/env.go
+++ b/platform/tester/env.go
@@ -45,7 +45,12 @@ func (e *EnvTest) WithDomain(key string) *EnvTest {
 // Replaces the default behavior (all keys are required).
 func (e *EnvTest) WithLiveTestRequirements(keys ...string) *EnvTest {
 	var countValuedVars int
+
 	for _, key := range keys {
+		if e.domainKey != key && !e.isManagedKey(key) {
+			panic(fmt.Sprintf("Unauthorized action, the env var %s is not managed or it's not the key of the domain.", key))
+		}
+
 		if _, ok := e.values[key]; ok {
 			countValuedVars++
 		}
@@ -120,15 +125,15 @@ func (e *EnvTest) liveTestExtra() bool {
 // Not related to the main environment variables.
 func (e *EnvTest) Apply(envVars map[string]string) {
 	for key, value := range envVars {
-		if e.isManagedKey(key) {
-			if len(value) == 0 {
-				os.Unsetenv(key)
-			} else {
-				os.Setenv(key, value)
-			}
-		} else {
+		if !e.isManagedKey(key) {
 			panic(fmt.Sprintf("Unauthorized action, the env var %s is not managed.", key))
 		}
+
+		if len(value) == 0 {
+			os.Unsetenv(key)
+		} else {
+			os.Setenv(key, value)
+		}
 	}
 }
 
diff --git a/providers/dns/auroradns/auroradns.go b/providers/dns/auroradns/auroradns.go
index d3cb76da..0553d85e 100644
--- a/providers/dns/auroradns/auroradns.go
+++ b/providers/dns/auroradns/auroradns.go
@@ -1,3 +1,4 @@
+// Package auroradns implements a DNS provider for solving the DNS-01 challenge using Aurora DNS.
 package auroradns
 
 import (
diff --git a/providers/dns/dns_providers_test.go b/providers/dns/dns_providers_test.go
index c953a2b2..230aab0e 100644
--- a/providers/dns/dns_providers_test.go
+++ b/providers/dns/dns_providers_test.go
@@ -1,51 +1,40 @@
 package dns
 
 import (
-	"os"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
-	"github.com/xenolf/lego/providers/dns/exoscale"
+	"github.com/xenolf/lego/platform/tester"
+	"github.com/xenolf/lego/providers/dns/exec"
 )
 
-var (
-	apiKey    string
-	apiSecret string
-)
-
-func init() {
-	apiSecret = os.Getenv("EXOSCALE_API_SECRET")
-	apiKey = os.Getenv("EXOSCALE_API_KEY")
-}
-
-func restoreExoscaleEnv() {
-	os.Setenv("EXOSCALE_API_KEY", apiKey)
-	os.Setenv("EXOSCALE_API_SECRET", apiSecret)
-}
+var envTest = tester.NewEnvTest("EXEC_PATH")
 
 func TestKnownDNSProviderSuccess(t *testing.T) {
-	defer restoreExoscaleEnv()
-	os.Setenv("EXOSCALE_API_KEY", "abc")
-	os.Setenv("EXOSCALE_API_SECRET", "123")
+	defer envTest.RestoreEnv()
+	envTest.Apply(map[string]string{
+		"EXEC_PATH": "abc",
+	})
 
-	provider, err := NewDNSChallengeProviderByName("exoscale")
+	provider, err := NewDNSChallengeProviderByName("exec")
 	require.NoError(t, err)
 	assert.NotNil(t, provider)
 
-	assert.IsType(t, &exoscale.DNSProvider{}, provider, "Not loaded correct DNS provider")
+	assert.IsType(t, &exec.DNSProvider{}, provider, "The loaded DNS provider doesn't have the expected type.")
 }
 
 func TestKnownDNSProviderError(t *testing.T) {
-	defer restoreExoscaleEnv()
-	os.Setenv("EXOSCALE_API_KEY", "")
-	os.Setenv("EXOSCALE_API_SECRET", "")
+	defer envTest.RestoreEnv()
+	envTest.ClearEnv()
 
-	_, err := NewDNSChallengeProviderByName("exoscale")
+	provider, err := NewDNSChallengeProviderByName("exec")
 	assert.Error(t, err)
+	assert.Nil(t, provider)
 }
 
 func TestUnknownDNSProvider(t *testing.T) {
-	_, err := NewDNSChallengeProviderByName("foobar")
+	provider, err := NewDNSChallengeProviderByName("foobar")
 	assert.Error(t, err)
+	assert.Nil(t, provider)
 }
diff --git a/providers/dns/dnsmadeeasy/dnsmadeeasy.go b/providers/dns/dnsmadeeasy/dnsmadeeasy.go
index 519a4451..d73d0afc 100644
--- a/providers/dns/dnsmadeeasy/dnsmadeeasy.go
+++ b/providers/dns/dnsmadeeasy/dnsmadeeasy.go
@@ -1,3 +1,4 @@
+// Package dnsmadeeasy implements a DNS provider for solving the DNS-01 challenge using DNS Made Easy.
 package dnsmadeeasy
 
 import (
diff --git a/providers/dns/dreamhost/dreamhost.go b/providers/dns/dreamhost/dreamhost.go
index cc0e3633..9edd27b7 100644
--- a/providers/dns/dreamhost/dreamhost.go
+++ b/providers/dns/dreamhost/dreamhost.go
@@ -1,4 +1,4 @@
-// Package dreamhost Adds lego support for http://dreamhost.com DNS updates
+// Package dreamhost implements a DNS provider for solving the DNS-01 challenge using DreamHost.
 // See https://help.dreamhost.com/hc/en-us/articles/217560167-API_overview
 // and https://help.dreamhost.com/hc/en-us/articles/217555707-DNS-API-commands for the API spec.
 package dreamhost
diff --git a/providers/dns/duckdns/duckdns.go b/providers/dns/duckdns/duckdns.go
index 2ac53f03..7581af17 100644
--- a/providers/dns/duckdns/duckdns.go
+++ b/providers/dns/duckdns/duckdns.go
@@ -1,4 +1,4 @@
-// Package duckdns Adds lego support for http://duckdns.org.
+// Package duckdns implements a DNS provider for solving the DNS-01 challenge using DuckDNS.
 // See http://www.duckdns.org/spec.jsp for more info on updating TXT records.
 package duckdns