com.fnproject.fn.testing.flow.FnFunctionStubBuilder Maven / Gradle / Ivy
/*
* Copyright (c) 2019, 2020 Oracle and/or its affiliates. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.fnproject.fn.testing.flow;
import com.fnproject.fn.testing.FunctionError;
import com.fnproject.fn.testing.PlatformError;
/**
* A builder for constructing stub external functions
*/
public interface FnFunctionStubBuilder {
/**
* Consume the builder and stub the function to return the provided byte array
*
* @param result A byte array returned by the function
* @return The original testing rule (usually {@link FlowTesting}. The builder is consumed.
*/
T withResult(byte[] result);
/**
* Consume the builder and stub the function to throw an error when it is invoked: this simulates a failure of the
* called function, e.g. if the external function threw an exception.
*
* @return The original testing rule (usually {@link FlowTesting}. The builder is consumed.
*/
T withFunctionError();
/**
* Consume the builder and stub the function to throw a platform error, this simulates a failure of the Fn Flow
* completions platform, and not any error of the user code.
*
* @return The original testing rule (usually {@link FlowTesting}. The builder is consumed.
*/
T withPlatformError();
/**
* Consume the builder and stub the function to perform some action; the action is an implementation of the
* functional interface {@link ExternalFunctionAction}, this gives finer grained control over the behaviour of the
* stub compared to {@link #withResult(byte[])}, {@link #withFunctionError()} and {@link #withPlatformError()}.
*
* Note that there are no thread-safety guarantees on any external state modified in the provided action. If shared
* external state is accessed, a synchronization mechanism should be used.
*
* @param f an action to apply when this function is invoked
* @return The original testing rule (usually {@link FlowTesting}. The builder is consumed.
*/
T withAction(ExternalFunctionAction f);
/**
* Represents the calling interface of an external function. It takes a byte[] as input,
* and produces a byte[] as output possibly throwing a {@link FunctionError} to simulate user code failure,
* or a {@link PlatformError} to simulate a failure of the Fn Flow completions platform.
*/
interface ExternalFunctionAction {
/**
* Run the external function action
*
* @param arg the body of the function invocation as a byte array
* @return the response to the function invocation as a byte array
* @throws FunctionError if the action should simulate a function failure
* @throws PlatformError if the action should simulate a platform failure
*/
byte[] apply(byte[] arg) throws FunctionError, PlatformError;
}
}