test: error out when bind mount source doesn't exist

This adds a test to verify that the server is checking whether the path
to be bind mounted actually exists on the server.

commands_test.go

@@ -679,3 +679,22 @@ func TestRunErrorBindMountRootSource(t *testing.T) {
 		<-c
 	})
 }
+
+// Expected behaviour: error out when attempting to bind mount non-existing source paths
+func TestRunErrorBindNonExistingSource(t *testing.T) {
+
+	cli := NewDockerCli(nil, nil, ioutil.Discard, testDaemonProto, testDaemonAddr)
+	defer cleanup(globalRuntime)
+
+	c := make(chan struct{})
+	go func() {
+		defer close(c)
+		if err := cli.CmdRun("-v", "/i/dont/exist:/tmp", unitTestImageID, "echo 'should fail'"); err == nil {
+			t.Fatal("should have failed to run when using /i/dont/exist as a source for the bind mount")
+		}
+	}()
+
+	setTimeout(t, "CmdRun timed out", 5*time.Second, func() {
+		<-c
+	})
+}