2 files changed, 26 insertions, 16 deletions
diff --git a/plumbing/transport/client/client.go b/plumbing/transport/client/client.go
index f749875..ea1e034 100644
--- a/plumbing/transport/client/client.go
+++ b/plumbing/transport/client/client.go
@@ -23,6 +23,11 @@ var Protocols = map[string]transport.Transport{
 
 // InstallProtocol adds or modifies an existing protocol.
 func InstallProtocol(scheme string, c transport.Transport) {
+	if c == nil {
+		delete(Protocols, scheme)
+		return
+	}
+
 	Protocols[scheme] = c
 }
 
@@ -35,5 +40,9 @@ func NewClient(endpoint transport.Endpoint) (transport.Transport, error) {
 		return nil, fmt.Errorf("unsupported scheme %q", endpoint.Scheme)
 	}
 
+	if f == nil {
+		return nil, fmt.Errorf("malformed client for scheme %q, client is defined as nil", endpoint.Scheme)
+	}
+
 	return f, nil
 }
diff --git a/plumbing/transport/client/client_test.go b/plumbing/transport/client/client_test.go
index a3715d2..0377d34 100644
--- a/plumbing/transport/client/client_test.go
+++ b/plumbing/transport/client/client_test.go
@@ -16,22 +16,6 @@ type ClientSuite struct{}
 
 var _ = Suite(&ClientSuite{})
 
-func (s *ClientSuite) TestNewClientHTTP(c *C) {
-	e, err := transport.NewEndpoint("http://github.com/src-d/go-git")
-	c.Assert(err, IsNil)
-
-	output, err := NewClient(e)
-	c.Assert(err, IsNil)
-	c.Assert(typeAsString(output), Equals, "*http.client")
-
-	e, err = transport.NewEndpoint("https://github.com/src-d/go-git")
-	c.Assert(err, IsNil)
-
-	output, err = NewClient(e)
-	c.Assert(err, IsNil)
-	c.Assert(typeAsString(output), Equals, "*http.client")
-}
-
 func (s *ClientSuite) TestNewClientSSH(c *C) {
 	e, err := transport.NewEndpoint("ssh://github.com/src-d/go-git")
 	c.Assert(err, IsNil)
@@ -49,11 +33,28 @@ func (s *ClientSuite) TestNewClientUnknown(c *C) {
 	c.Assert(err, NotNil)
 }
 
+func (s *ClientSuite) TestNewClientNil(c *C) {
+	Protocols["newscheme"] = nil
+	e, err := transport.NewEndpoint("newscheme://github.com/src-d/go-git")
+	c.Assert(err, IsNil)
+
+	_, err = NewClient(e)
+	c.Assert(err, NotNil)
+}
+
 func (s *ClientSuite) TestInstallProtocol(c *C) {
 	InstallProtocol("newscheme", &dummyClient{})
 	c.Assert(Protocols["newscheme"], NotNil)
 }
 
+func (s *ClientSuite) TestInstallProtocolNilValue(c *C) {
+	InstallProtocol("newscheme", &dummyClient{})
+	InstallProtocol("newscheme", nil)
+
+	_, ok := Protocols["newscheme"]
+	c.Assert(ok, Equals, false)
+}
+
 type dummyClient struct {
 	*http.Client
 }