asset/installconfig: move uri validation to validation package

Move the uri validation from pkg/asset/installconfig/libvirt to pkg/validation
for consistency with other validation functions.

https://jira.coreos.com/browse/CORS-850

pkg/asset/installconfig/libvirt/libvirt.go

@@ -3,14 +3,13 @@ package libvirt
 
 import (
 	"context"
-	"fmt"
-	"net/url"
 
 	"github.com/pkg/errors"
 	survey "gopkg.in/AlecAivazis/survey.v1"
 
 	"github.com/openshift/installer/pkg/rhcos"
 	"github.com/openshift/installer/pkg/types/libvirt"
+	"github.com/openshift/installer/pkg/validate"
 )
 
 const (
@@ -55,17 +54,5 @@ func Platform() (*libvirt.Platform, error) {
 // uriValidator validates if the answer provided in prompt is a valid
 // url and has non-empty scheme.
 func uriValidator(ans interface{}) error {
-	return validURI(ans.(string))
-}
-
-// validURI validates if the URI is a valid URI with a non-empty scheme.
-func validURI(uri string) error {
-	parsed, err := url.Parse(uri)
-	if err != nil {
-		return err
-	}
-	if parsed.Scheme == "" {
-		return fmt.Errorf("invalid URI %q (no scheme)", uri)
-	}
-	return nil
+	return validate.URI(ans.(string))
 }

pkg/validate/validate.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"net"
+	"net/url"
 	"regexp"
 	"strconv"
 	"strings"
@@ -220,3 +221,15 @@ func SSHPublicKey(v string) error {
 	_, _, _, _, err := ssh.ParseAuthorizedKey([]byte(v))
 	return err
 }
+
+// URI validates if the URI is a valid absolute URI.
+func URI(uri string) error {
+	parsed, err := url.Parse(uri)
+	if err != nil {
+		return err
+	}
+	if !parsed.IsAbs() {
+		return fmt.Errorf("invalid URI %q (no scheme)", uri)
+	}
+	return nil
+}

pkg/validate/validate_test.go

@@ -384,3 +384,32 @@ func TestSSHPublicKey(t *testing.T) {
 		})
 	}
 }
+
+func TestURI(t *testing.T) {
+	cases := []struct {
+		name  string
+		uri   string
+		valid bool
+	}{
+		{
+			name:  "valid",
+			uri:   "https://example.com",
+			valid: true,
+		},
+		{
+			name:  "missing scheme",
+			uri:   "example.com",
+			valid: false,
+		},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			err := URI(tc.uri)
+			if tc.valid {
+				assert.NoError(t, err)
+			} else {
+				assert.Error(t, err)
+			}
+		})
+	}
+}