René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Reimagine how the app determines its context","articleBody":"The app currently determines the context it's operating under from several sources:\r\n\r\n- the filesystem (e.g. current directory name)\r\n- app config file (currently `~/.config/hub` in YAML format)\r\n- environment variables (e.g. `GH_REPO`, `GITHUB_TOKEN`, etc.)\r\n- git config (via `git config` \u0026 `git remote -v`, sources: `.git/config` \u0026 `~/.gitconfig`)\r\n- git tree (e.g. current branch, current commit SHA)\r\n- SSH config (sources: `~/.ssh/config` \u0026 `/etc/ssh_config`) - resolves SSH aliases for hostnames listed under git remotes\r\n- GitHub API (e.g. info about the current repo)\r\n\r\nWhen something like `gh pr create` gets run, quite a lot happens under the hood. For example:\r\n1. Current GitHub user and OAuth token are obtained from app config;\r\n1. The list of git remotes gets queried and parsed;\r\n2. The \"main\" remote (i.e. one pointing to the canonical GitHub repo) is determined by searching for the first one in this list: `upstream`, `github`, `origin`;\r\n3. The base branch is determined via `git symbolic-ref refs/remotes/\u003cREMOTE\u003e/HEAD` (alternatively, by querying repo information via API);\r\n4. The head branch is determined by looking at the push target for the current branch:\r\n   - explicit upstream branch configuration is first looked up;\r\n   - otherwise, the first remote that has a same-named tracking branch is the likely push target;\r\n   - otherwise, assume the branch isn't pushed yet, so determine the first remote that points to a GitHub project that the current user has write capabilities to;\r\n   - if such a remote doesn't exist, create one by forking;\r\n5. A person's preferred text editor is looked up for authoring PR description text;\r\n6. PR creation operation proceeds.\r\n\r\nTo facilitate all these lookups, the current codebase has a loose system of mapping one piece of information to another. For example:\r\n- current git repo 👉 default (\"base\") branch\r\n- current git repo 👉 \"main\" remote\r\n- git remote 👉 GitHub repository (a.k.a. \"project\") it maps to\r\n- tracking branch 👉 git remote it belongs to\r\n- current user 👉 the person's fork\r\n\r\nSince a lot of lookups start from the current git repo (based on the current working directory at the time that the CLI app runs), there is a LocalRepo struct that encapsulates performing some of these mappings, while additional mapping logic is scattered across individual methods such as `Branch.RemoteName()`, `Remote.Project()`, etc. Some problems I find with the current system:\r\n- Inconsistent naming (e.g. \"repository\" vs. \"project\", the ambiguity of \"branch\")\r\n- Blurred responsibility between objects (e.g. why would a Branch have to know how to map itself to a Remote, or a Remote to a Project?)\r\n- Methods that do too much but don't sufficiently betray intent (e.g. `LocalRepo.RemoteBranchAndProject()`)\r\n- Hard to stub out in tests (ideally, unit tests should be able to set up a mock context in memory rather than having to write a test git repo out to fileystem)\r\n- **All** of this code is under the same Go package: \"github\".\r\n\r\nMy rough proposal for starting to address this:\r\n- [x] Get rid of methods and structs named \"Project\" from the codebase;\r\n- [x] Get rid of LocalRepo;\r\n- [x] Design an abstraction around `git config` that is able to mock responses in memory;\r\n- [x] Consider moving `github/branch.go` to under the \"git\" package;\r\n- [ ] Consider isolating `git/ssh_config.go` to its own package;\r\n- [ ] Minimize the implementation of Remote and instead perform necessary mappings through a separate service object;\r\n- [x] Minimize the \"github\" package until it's ideally gone;\r\n- [ ] Write Go unit tests along the way to confirm the testability of these implementations.\r\n\r\nLet's revise all this as we go along! Thank you for reading. 🙇 ","author":{"url":"https://github.com/mislav","@type":"Person","name":"mislav"},"datePublished":"2019-10-07T17:49:57.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":4},"url":"https://github.com/2/cli/issues/2"}