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In Foundry, we have a data pipeline where we want to insert a code node (repo or workbook) that detects anomalies and then sends and email or some other alert about the problem.
Having trouble finding this in the documentation, can someone point me to it?
Ideally we would love to have the code trigger the Scheduler to do a pipeline run to create a REPORT, (maybe even Quiver, to do some timeline analysis). Is this possible? Are there examples in the documentation?
Check out the documentation in the Data Health section of the platform documentation. There are a number of patterns possible, including defining data expectations in your code.
Whether defined as expectations or dataset health checks, failures can be set up to create Issues within the platform, which can have default assignees (individuals or groups) that will also send notifications, which are both in platform and over email (depending on per-user configuration).
Health check failures will also automatically populate the data health tab in the Project Catalog view, which can serve as a dashboard to view the overall health of the project. You can also surface these in the Data Lineage view with a coloring based on Data Health to understand issues across the breadth of the pipeline.
For a comprehensive approach to pipeline health, review the Pipelines and best practices section in the Code Repositories documentation.
These days I've read several articles about BDD to find what it is talking about. Now I get a basic understandings, but still not clear about the whole process.
The following is what I think to do in a BDD process:
All the stakeholders(BA, customer, Dev, QA) are sitting together to discuss the requirements, and write the agreed features on story cards. Here I take a "user registeration" feature as example:
As a user,
I want to register on the system,
so that I can use its services
Create several scenarios in Given/When/Then format, and here is one of them:
Scenario: user successfully register
Given an register page
And an un-registered user
When the user fills username "Jeff" and password "123456"
And click on "Register"
Then the user can see a "Success" message
And the user "Jeff" is created in the system
Implement this scenario with some BDD testing framework, say cucumber-jvm, like:
import cucumber.api.java.en.Given;
public class Stepdefs {
#Given("an register page")
public void an_register_page throws Throwable {
// ...
}
#Given("an un-registered user")
public void an_register_page throws Throwable {
// ...
}
// ...
}
for the steps one by one.
But I soon find myself in trouble: there are pages, models, maybe databases need for this scenario, seems a lot of thing to do.
What should I do now?
What should I do now? Do I need to discuss this scenario with all the stakeholders? For BA/Customer/QA, I don't think they really care about the implementations, is it a good idea to discuss it with some other developers?
Suppose after I discuss it with some other developers, we agree to split it to several small parts. Can we make these small parts as "scenario"s with Scenario/Given/When/Then format as what we just did with cucumber-jvm, or can we use JUnit as we normally do in TDD?
1. If choose "cucumber-jvm", it seems a little heavy for small part
2. If choose JUnit, we need to involve more than one testing framework in a project
3. Is it the best if there is a single testing framework to do both things (not sure if there is)
Suppose I choose option 2, using JUnit for the small tasks
The following is what I will do after this decision:
Now we create new small tests to drive implementations, like creating user in database, as we normally do in TDD. (red->green->refactoring). And we don't care the cucumber test Scenario: user successfully register (which is failed) for now, just leave it there. Right?
We develop more small tests with JUnit, made them red -> green -> refactored. (And the imcomplete cucumber test is always failed)
Until all the small tests are passed, we turn to the cucumber test Scenario: user successfully register. Completed it and make sure it turn green at last.
Now develop another scenario, if it's easy, we can implement it just with cucumber, otherwise we will have to split it and write several jUnit test
There are definitely a lot of mis-understandings, even very basic ones. Because I don't find myself gain much value from BDD except the "discuss with all stakeholders" part.
Where is my mistake? Appreciate for any sugguestions!
Don't start with logging in; start with the thing that's different to the other systems out there. Why is someone logging in? Why do they want to use the service? Hard-code a user, pretend they're logged in, focus on the value.
If you focus on UI details you tie yourself to the UI very strongly, and it makes the UI hard to change. Instead, look at what capabilities the system is delivering. I don't recommend using a login scenario anyway, but if I did, I'd expect it to look more like:
Given Jeff isn't registered with the site
When he registers with the username "Jeff" and password "123456"
Then his account creation should be confirmed
And he should be invited to log in for the first time.
Look up "declarative vs. imperative" here to see more on this.
If your UI is really in flux, try out the scenario manually until the UI has settled down a bit. It will be easier to automate then. As you move into more stable scenarios it will be better to automate first (TDD-style).
What should you do now? Well, most people don't write class-level tests for the UI, so don't worry about it until you start driving out the controller and presenter layers. It's normally easier to have frameworks in the same language, but two different frameworks is fine. Cucumber / RSpec, JBehave / JUnit, SpecFlow / NUnit are pretty typical combinations. Do the smallest amount you need to get that first scenario working. It won't be much, because you can hard-code a lot of it. The second scenario will start introducing more interesting behaviour, and then you'll start to see your class-level tests emerge.
BTW, BDD started at a class level, so you can do the same thing with the classes; think of an example of how you might use it, write "Given, When, Then" in comments if your framework doesn't work that way already, and then fill in the gaps!
Yes, your Cucumber scenario will be red throughout, until it isn't.
Ideally you'll be making one last unit test and the Cucumber scenario pass at the same time, rather than just writing a bit of extra code. It's very satisfying to see it finally go green.
The original point of BDD was to get rid of the word "test", since it causes people to think of things like TDD as being about testing. TDD's really about clean design; understanding the responsibilities and behaviour of your code, in the same way that scenarios help you understand the capabilities and behaviour of your system. It should be normal to write both system-level scenarios and class-level tests too.
You're already ahead of all the people who forget to discuss the scenarios before they start coding, though! The conversations with stakeholders are the most important part. You might get value out of including a tester in those conversations. Testers are very good at spotting scenarios that other people miss.
It looks like you're pretty much on the right track where the rest of the process is concerned. You might find some of the other BDD answers in my profile helpful for you too. Congrats and good luck!
I think doing registration/sign_in first is a really good thing to do when you are learning the mechanics of doing BDD. Pretty much everyone understands why you would want to sign into a system, and everyone understands that the system has to know who you are before you can do this, so you have to register first.
Doing this simple task allows you to concentrate on a smaller subset of BDD. By narrowing your focus you can improve quality, whilst being aware that there is much more to learn a little later on.
To write your sign in scenarios you need to focus on two things:
writing scenarios
implementing step definitions
These are the basic mechanics of BDD, but they are only a small part of the overall process. Still I think you'd benefit from working on them because at the moment you are not executing the mechanics very well, which is to be expected because you are new to this.
When you write scenarios you should concentrate on 'what' you are doing and 'why' you are doing it. Scenarios have no need to know anything about 'how' you do things. Anything to do with filling in stuff, clicking on stuff etc. is a smell. When your scenarios only deal with the what and why they become much simpler.
Feature: Registration
A pre-requistite for signing in, see sign_in.feature
Scenario: Register
Given I am a new user
When I register
Then I should be registered
Feature: Sign in
Dependant on registration ...
I want to sign in so I can have personalised content and ...
Scenario: Sign in
Given I am registered
When I sign in
Then I should be signed in
You really don't much more than this to drive the development of a simple sign_in system. Once you have that running you can deal with some sad paths e.g.
Scenario: Sign in with bad password
Given I am registered
When I sign in with a bad password
Then I should not be signed in
And I should be told ...
If you implement things nicely this sad path scenario should be trivial to implement as all the infrastructure is already in place to sign in, all that is different is you are using a bad password.
You can see an example of this at https://github.com/diabolo/cuke_up. The way to use this example is follow the commit history, and in particular notice how I am using the extract_method refactor to take all the code out of the step definitions. Each method I extract is a tool to reused when writing subsequent scenarios. Making an effective set of tools is the key to productivity when implementing scenarios.
Nowadys sign_up is so simple because we can rely on a 3rd party library and their unit tests. This means we can get pretty good results without ever having to worry about the transition to our own code and doing bits of TDD. So for now there really is no need to think about TDD.
So long as you are aware that you are only doing a small subset of BDD, I think you can successfully use this approach to provide foundations for all the extra stuff you have to deal with when working with the things that differentiate your system from others.
To summarize, just focus on
writing simple scenarios
making your step definitions elegant
creating tools (extracted methods) that can be used in the next scenario you write
You have plenty of time to learn the other stuff, and it will be much easier if your basic mechanics are better developed.
In chamilo LMS, if you put a test in a learning path, it doesn't use the grade as passing, it uses completion as passing. So if you want the scores to count you have to tell users in a learning path, "Hey go find such and such a test in the exams section." I am trying to find a way to at least provide a link that will take the user directly to a specific test.
The chamilo forum is being hopeless spammed by a bot right now, so I cant get help there.
The reason why tests are graded by completion in learning paths is because learning paths are a teaching tool, by opposition to evaluation tool. As such, including tests there should only be used as a way to control whether you are good to move to the next chapter (using prerequisites) or not.
Teal exams should be taken apart for two reasons:
to allow the student to prepare reasonnably (study on one side then, when (s)he's ready, enter the exam as if it was something formal
to reduce possible interferences of JavaScript that is generated in the learning path context (you never know what other JS a teacher might add ti his/her tests)
In either case, you can still see the results of the tests from the user's tracking page (there's a column showing through which learning path it was graded, to make it clear).
You can use the URL of the test, then create a link to the test, then include the link in the learning path (this will open it as a content page but should track the results (not sure about that, you'll have to try it out) as if it was taken from out of a learning path.
Or you can also just put the link in an HTML document with a small explanation at the end of your learning path. This should send the user directly out of the learning path context and into the exercise context.
How many ways are there to learn implementing workflow of a software? What are them?
If you mean the user workflow, how the user is guided through the software...
I usually use some sort of state machine to limit what functionality can be triggered by the user and what information will be presented to the user in a particular state of the workflow. This way I can concentrate on designing each segment of the flow in its own "sandbox" and decision making becomes a lot easier.
If you do not mean user workflow, you can ignore this reply.
Usually you do have steps in workflow. Step consist of some precondition (business logic hidden from UI), some user interaction (user entering some data, and doing some “user stuff”), and post conditions. Usually user interaction part has one or more user chosen “exists”, and every exit consist it’s own post condition (usually every user exit has it’s own business logic depending of a meaning of an exit from a step). Exits navigate workflow to next step. Sometimes you can have fully automatic steps (i.e. using some external data source, calling some web service, important calculation, and so on).
If your workflow is simple, you may implement it as a set of classes representing each step, and configuration of steps order can be put in XML. When your workflow will grow bigger, and bigger, it may be reasonable to search for some workflow engine, (discussion of WF engines is I think beyond the scope of this question).
One important thing – steps can be orthogonal, but it is harder to design. If your steps rely one on another, person configuring workflow and steps order must be fully aware of such dependencies (e.g: user address step will probably depends on user object creation step, and removing user object creation step from a workflow, will result in trying to access nonexistent object).
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I'm working on improving our group's development process, and I'm considering how best to implement Design By Contract with Test-Driven Development. It seems the two techniques have a lot of overlap, and I was wondering if anyone had some insight on the following (related) questions:
Isn't it against the DRY principle to have TDD and DbC unless you're using some kind of code generator to generate the unit tests based on contracts? Otherwise, you have to maintain the contract in two places (the test and the contract itself), or am I missing something?
To what extent does TDD make DbC redundant? If I write tests well enough, aren't they equivalent to writing a contract? Do I only get added benefit if I enforce the contract at run time as well as through the tests?
Is it significantly easier/more flexible to only use TDD rather than TDD with DbC?
The main point of these questions is this more general question: If we're already doing TDD properly, will we get a significant benefit for the overhead if we also use DbC?
A couple of details, though I think the question is largely language-agnostic:
Our team is very small, <10 programmers.
We mostly use Perl.
Note the differences.
Design driven by contract. Contract Driven Design.
Develop driven by test. Test Driven Development.
They are related in that one precedes the other. They describe software at different levels of abstraction.
Do you discard the design when you go to implementation? Do you consider that a design document is a violation of DRY? Do you maintain the contract and the code separately?
Software is one implementation of the contract. Tests are another. User's manual is a third. Operations guide is a fourth. Database backup/restore procedures are one part of an implementation of the contract.
I can't see any overhead from Design by Contract.
If you're already doing design, then you change the format from too many words to just the right words to outline the contractual relationship.
If you're not doing design, then writing a contract will eliminate problems, reducing cost and complexity.
I can't see any loss of flexibility.
start with a contract,
then
a. write tests and
b. write code.
See how the two development activities are essentially intertwined and both come from the contract.
I think there is overlap between DbC and TDD, however, I don't think there is duplicated work: introducing DbC will probably result in a reduction of test cases.
Let me explain.
In TDD, tests aren't really tests. They are behavioral specifications. However, they are also design tools: by writing the test first, you use the external API of your object under test – that you haven't actually written yet – in the same way that a user would. That way, you design the API in a way that makes sense to a user, and not in the way that makes it easiest for you to implement. Something like queue.full? instead of queue.num_entries == queue.size.
This second part cannot be replaced by Contracts.
The first part can be partially replaced by contracts, at least for unit tests. TDD tests serve as specifications of behavior, both to other developers (unit tests) and domain experts (acceptance tests). Contracts also specify behavior, to other developers, to domain experts, but also to the compiler and the runtime library.
But contracts have fixed granularity: you have method pre- and postconditions, object invariants, module contracts and so on. Maybe loop variants and invariants. Unit tests however, test units of behavior. Those might be smaller than a method or consist of multiple methods. That's not something you can do with contracts. And for the "big picture" you still need integration tests, functional tests and acceptance tests.
And there is another important part of TDD that DbC doesn't cover: the middle D. In TDD, tests drive your development process: you never write a single line of implementation code unless you have a failing test, you never write a single line of test code unless your tests all pass, you only write the minimal amount of implementation code to make the tests pass, you only write the minimal amount of test code to produce a failing test.
In conclusion: use tests to design the "flow", the "feel" of the API. Use contracts to design the, well, contract of the API. Use tests to provide the "rhythm" for the development process.
Something like this:
Write an acceptance test for a feature
Write a unit test for a unit that implements a part of that feature
Using the method signature you designed in step 2, write the method prototype
Add the postcondition
Add the precondition
Implement the method body
If the acceptance test passes, goto 1, otherwise goto 2
If you want to know what Bertrand Meyer, the inventor of Design by Contract, thinks about combining TDD and DbC, there is a nice paper by his group, called Contract-Driven Design = Test-Driven Development - Writing Test Cases. The basic premise is that contracts provide an abstract representation of all possible cases, whereas test cases only test specific cases. Therefore, a suitable test harness can be automatically generated from the contracts.
I would add:
the API is the contract for the programmers, the UI definition is the contract with the clients, the protocol is the contract for client-server interactions. Get those first, then you can take advantage of parallel development tracks and not get lost in the weeds. Yes, periodically review to make sure requirements are met, but never start a new track without the contract. And 'contract' is a strong word: once deployed, it must never change. You should include versioning management and introspection from the get-go, changes to the contract are only implemented by extension sets, version numbers change with these, and then you can do things like graceful degradation when dealing with mixed or old installations.
I learned this lesson the hard way, with a large project that wandered off into never-never land, then applied it the right way later when seriously under the gun, company-survival, short fuse timeline. We defined the protocol, defined and wrote a set of protocol emulations for each side of the transactions (basically canned message generators and received message checker, one evenings' worth of two-brained coding), then parted to separately write the server and client ends of the app. We recombined the night of the show, and it just worked. Requirements, design, contract, test, code, integrate. In that order. Repeat until baked.
I am a little leery of design by TLA. As with Patterns, buzz-word compliant recipes are a good guide, but it is my experience that there is no such thing as a one-size-fits-all design or project management procedure. If you are doing things precisely By The Book (tm) then, unless it is a DOD contract with DOD procedural requirements, you will probably get into trouble somewhere along the way. Read the Book(s), yes, but be sure tounderstand them, and then take into account also the people side of your team. Rules that are only enforced by the Book will not get enforced uniformly - even when tool-enforced there can be drop-outs (e.g. svn comments left empty or cryptically brief). Procedures only tend to get followed when the tool chain not only enforces them but makes following easier than any possible short-cuts. Believe me, when the going gets tough, the short-cuts get found, and you may not know about the ones that got used at 3am until it is too late.
You can also use executable acceptance tests that are written in the domain language of the contract. It might not be the actual "contract", but half way between unit tests and the contract.
I would recomment using Ruby Cucumber
http://github.com/aslakhellesoy/cucumber
But since you are a Perl shop, then maybe you can use my own small attempt at p5-cucumber.
http://github.com/kesor/p5-cucumber
Microsoft has done work on automatic generation of unit tests, based on code contracts and parameterized unit test. E.g. the contract says the count must be increased by one when an item is added to a collection, and the parameterized unit test say how to add “n” items to a collection. Pex will then try to create a unit test that proves the contract is broken. See this video for a overview.
If this works, your unit test will only have to be written for one example of each thing you are trying to test, and PEX will be able to then work out witch data items will break the test.
I had some ruminations about that topic some time ago.
You may want to take a look at
http://gleichmann.wordpress.com/2007/12/09/test-driven-development-and-design-by-contract-friend-or-foe/
When you are using TDD to implement a new method, you need some input: you need to know the assertions to check in your tests. Design-by-contract gives you those assertions: they are the post-conditions and invariants of the method.
I have found DbC very handy for jumpstarting the red-green-refactor cycle because it helps in identifying unit tests to start with. With DbC I start thinking about pre-conditions that the object being TDD-ed must handle and each pre-condition might represent a failing unit test to start a red-green-refactor cycle. At some point I switch to start the cycle with a failing unit test for a post-condition, and then just keep the TDD flow going. I have tried this approach with newcomers to TDD and it really works in kickstarting the TDD mindset.
In summary, think of DbC as an effective way to identify key behavioral unit tests. DbC helps at analyzing inputs (pre-conditions) and outputs(post-conditions), which are the two things that we need to control (inputs) and observe (outputs) to write testable software (a similar aim of TDD).