tests: Remove dependency on check.v1 (#5034)

This PR addresses a long standing dependency on
`gopkg.in/check.v1` project used for our tests.
All tests are re-written to use the go default
testing framework instead.

There was no reason for us to use an external
package where Go tools are sufficient for this.

cmd/net_test.go

@@ -175,6 +175,21 @@ func TestGetAPIEndpoints(t *testing.T) {
 	}
 }
 
+// Ask the kernel for a free open port.
+func getFreePort() string {
+	addr, err := net.ResolveTCPAddr("tcp", "localhost:0")
+	if err != nil {
+		panic(err)
+	}
+
+	l, err := net.ListenTCP("tcp", addr)
+	if err != nil {
+		panic(err)
+	}
+	defer l.Close()
+	return fmt.Sprintf("%d", l.Addr().(*net.TCPAddr).Port)
+}
+
 // Tests for port availability logic written for server startup sequence.
 func TestCheckPortAvailability(t *testing.T) {
 	// Make a port is not available.