## page was renamed from LEP/BugRelationships
= Bug dependencies =
Bug dependencies in Launchpad will allow users to record the dependency between two or more bugs in the system. So, where one bug is blocking another being fixed, that can be shown as a relationship and so on.
'''Contact:''' gmb <
>
'''On Launchpad:''' [[https://bugs.launchpad.net/launchpad-project/+bugs?field.tag=story-bug-dependencies|Bugs tagged story-bug-dependencies]]
== What this is not ==
1. A reimplementation of Blueprints (though as a side effect of its development we may see Blueprint usage drop off for some use-cases).
2. Anything to do with bug cloning and linking as detailed in [[LEP/BugLinking]].
== Rationale ==
Bug dependencies are an oft-requested feature of the Launchpad Bug Tracker and is something that would benefit the Launchpad development team itself.
As Launchpad has moved into feature-based development it has become more important to be able to track how much of the work on a given feature is done, whilst also tracking whether or not the feature itself can be considered complete.
Once the bug dependencies feature is implemented, developers will be able to declare the dependecies between two or more bugs. That means that they can clearly see, when starting a task, which bugs must be dealt with in which order. This can save a great deal of time, especially when (in the case of Launchpad, for example) it's not always obvious to a developer that other bugs block the one that they've just picked up.
== Stakeholders ==
* Launchpad Team Lead (Francis Lacoste)
* Launchpad Product Manager (Matthew Revell)
* Launchpad Technical Architect (Robert Collins)
* Launchpad Squad Leaders (Gary Poster, Julian Edwards, Curtis Hovey, Deryck Hodge)
* OEM (Joey Stanford, Steve Magoun, Cody A.W. Somerville)
* Hardware enablement (Chris Van Hoof, Hugh Blemings)
* Ubuntu (Bryce Harrington)
== User stories ==
=== Long-form ===
As a Launchpad developer, working on feature XYZ, I want to be able to know where to start my work. Initially, I may think that I should start with Bug A, which is the simplest of the bugs tagged for the feature. However, further investigation reveals that Bug A is blocked by Bug B and Bug C. These bugs are not actually related to each other, but they are both in turn blocked by Bug D. The dependency graph for Bug A now looks something like this:
{{{
D
/ \
B C
\ /
A
}}}
Therefore, I need to start working not on Bug A, but on Bug D.
=== Short-form ===
'''As an''' Ubuntu developer<
>
'''I want ''' to be able to mark a bug as being blocked by another bug<
>
'''so that ''' it is obvious in which order bugs need to be tackled<
>
'''As an''' upstream project maintainer <
>
'''I want''' to be able to mark a bug in my project as being the result of a bug in a dependency<
>
'''So that''' I can track the bug in my project separately from the dependency bug.
'''As an''' upstream project maintainer <
>
'''I want''' Launchpad to notify me when all the dependencies for a bug have been resolved.
'''So that''' I can commence work on the dependant bug.
'''As a ''' Launchpad Product Manager (or TA) <
>
'''I want ''' to be able to mark bug X as a "meta bug" of bugs A, B and C<
>
'''so that ''' I can use the bug tracker to track the development of features<
>
'''As a ''' Launchpad Product Manager (or TA) <
>
'''I want ''' Launchpad to automatically close a meta-bug once all its child bugs are closed<
>
'''so that ''' I only have to watch the one bug in order to know that a given feature is complete<
>
'''As a ''' Launchpad developer <
>
'''I want ''' to be able to see the dependency/relationship tree for a bug<
>
'''so that ''' I know where to start with my work to fix the bug.<
>
== Constraints and Requirements ==
=== Must ===
1. Provide the ability to say that one bug is dependent on another being fixed.
2. Provide the ability to create a family of two or more bugs, headed by a "meta bug". The status of "meta" bug will be automatically managed by Launchpad, so that "meta" bugs are resolved only when all the bugs which they encompass are resolved.
3. Provide a way to display clearly to users what needs to happen for a bug to become unblocked or, in the case of meta bugs, what must happen for a bug to be resolved.
=== Nice to have ===
1. Dependency graphs for bugs
=== Must not ===
=== Out of scope ===
1. Completely replacing (and removing) Blueprints.
== Subfeatures ==
== Success ==
=== How will we know when we are done? ===
1. A user will be able to say that the resolution of one bug is blocked by one or more other bugs.
2. Users will receive notifications when all the dependencies of a bug are resolved.
3. A user will be able to declare that a bug will be automatically resolved when all its dependencies are resolved.
4. We will be able to model Launchpad feature development stories using bug relationships rather than bug tags.
=== How will we measure how well we have done? ===
1. We will measure how often the identified stakeholders' teams each mark bug dependencies per week
2. We can review bug comments for newly filed bugs for the stakeholder groups to see if bug dependencies are now being modeled in the data rather than in the comments
3. We can review the percentage of bugs mentioned in comments that are not duplicates or related via a dependency chain; should this percentage differ significantly from the value before we implemented bug relationships it would indicate significant uptake of this feature (assuming other factors remain approximately stable).
4. We will hold user-acceptance interviews with the relevant stakeholders.
== Thoughts? ==
* I've no idea how to measure success at this stage. I'd like to say "people use this more than they use Blueprints" but that's a) not a metric and b) foolish.
* We probably need a lot of buy-in from the non-LP stakeholders to be able to consider this "done" but I'm not sure what form that buy-in would take.
== Comments ==
* gary 2011-09-26: Thank you, Graham! My comments got long, so I moved them to [[/GaryComments|a separate page]].
* mrevell 2011-10-11: Is there anything we can/should do as part of this feature to smooth the path to merging the blueprint, answer and bug trackers into a unified issue tracker (Project Highlander: i.e. there can be only one ... issue tracker)