tests: don't call to flag.Parse() from init()

Since golang 1.13 packages that call flag.Parse during package initialization
may cause tests to fail[1].
Add a new function named `KataInit` to initialize the tests and parse
the command line, this function needs to be called as soon as possible,
preferably from `TestMain`.

[1] - https://golang.org/doc/go1.13#testing

fixes kata-containers#2195

Signed-off-by: Julio Montes <[email protected]>

command.go

@@ -6,22 +6,12 @@ package tests
 
 import (
 	"bytes"
-	"flag"
 	"fmt"
 	"os/exec"
 	"syscall"
 	"time"
 )
 
-// Runtime is the path of a Kata Containers Runtime
-var Runtime string
-
-// Timeout specifies the time limit in seconds for each test
-var Timeout int
-
-// Hypervisor is the hypervisor currently being used with Kata
-var Hypervisor string
-
 // Command contains the information of the command to run
 type Command struct {
 	// cmd exec.Cmd
@@ -31,14 +21,6 @@ type Command struct {
 	Timeout time.Duration
 }
 
-func init() {
-	flag.StringVar(&Runtime, "runtime", "", "Path of the desired Kata Runtime")
-	flag.IntVar(&Timeout, "timeout", 5, "Time limit in seconds for each test")
-	flag.StringVar(&Hypervisor, "hypervisor", "", "The hypervisor currently being used with Kata")
-
-	flag.Parse()
-}
-
 // NewCommand returns a new instance of Command
 func NewCommand(path string, args ...string) *Command {
 	c := new(Command)

config.go

@@ -6,6 +6,7 @@
 package tests
 
 import (
+	"flag"
 	"io/ioutil"
 	"log"
 	"os"
@@ -14,6 +15,15 @@ import (
 	"github.com/BurntSushi/toml"
 )
 
+// Runtime is the path of a Kata Containers Runtime
+var Runtime string
+
+// Timeout specifies the time limit in seconds for each test
+var Timeout int
+
+// Hypervisor is the hypervisor currently being used with Kata
+var Hypervisor string
+
 // KataConfiguration is the runtime configuration
 type KataConfiguration struct {
 	Hypervisor map[string]hypervisor
@@ -95,7 +105,21 @@ var KataConfig KataConfiguration
 var KataHypervisor string
 
 func init() {
+	flag.StringVar(&Runtime, "runtime", "", "Path of the desired Kata Runtime")
+	flag.IntVar(&Timeout, "timeout", 5, "Time limit in seconds for each test")
+	flag.StringVar(&Hypervisor, "hypervisor", "", "The hypervisor currently being used with Kata")
+}
+
+// KataInit initializes the kata test suite.
+// This function should be called as soon as possible
+// preferably from `TestMain`
+func KataInit() {
 	var err error
+
+	// Since golang 1.13 packages that call flag.Parse during package initialization
+	// may cause tests to fail. https://golang.org/doc/go1.13#testing
+	flag.Parse()
+
 	kataConfigPath := DefaultKataConfigPath
 
 	args := []string{"--kata-show-default-config-paths"}