autoformat bot in CI (#437)

* draft autoformat bot

* stop CI on outdatted commits

* simplify the cache action

* misformat on purpose

* a PR template explaining the presence of a bot

* mention resetting the test runner in the PR template

* linter bot commit -- feel free to overwrite

---------

Co-authored-by: Krastanov <[email protected]>

Author: Krastanov

.github/pull_request_template.md

@@ -0,0 +1,7 @@
+Please make sure to leave this PR editable by maintainers of this repo.
+
+Please make sure you have consulted [CONTRIBUTING](https://github.com/JuliaGraphs/Graphs.jl/blob/master/CONTRIBUTING.md)
+
+The linter bot might add new commits to your PR (e.g. to take care of formatting issues). Feel free to overwrite these commits. 
+
+If the linter bot is the last one to put in a commit, **THE TESTS WILL NOT RUN**. Either lint/format your contributions yourself as described in CONTRIBUTING.md or close&reopen the PR to reset the test runner.

.github/workflows/ci.yml

@@ -1,6 +1,12 @@
 name: CI
 env:
   JULIA_NUM_THREADS: 2
+concurrency:
+  # group by workflow and ref; the last slightly strange component ensures that for pull
+  # requests, we limit to 1 concurrent job, but for the master branch we don't
+  group: ${{ github.workflow }}-${{ github.ref }}-${{ (github.ref != 'refs/heads/master' && github.ref != 'refs/heads/main') || github.run_number }}
+  # Cancel intermediate builds, but only if it is a pull request build.
+  cancel-in-progress: ${{ startsWith(github.ref, 'refs/pull/') }}
 on:
   pull_request:
     branches:
@@ -32,16 +38,7 @@ jobs:
         with:
           version: ${{ matrix.version }}
           arch: ${{ matrix.arch }}
-      - uses: actions/cache@v4
-        env:
-          cache-name: cache-artifacts
-        with:
-          path: ~/.julia/artifacts
-          key: ${{ runner.os }}-test-${{ env.cache-name }}-${{ hashFiles('**/Project.toml') }}
-          restore-keys: |
-            ${{ runner.os }}-test-${{ env.cache-name }}-
-            ${{ runner.os }}-test-
-            ${{ runner.os }}-
+      - uses: julia-actions/cache@v2
       - uses: julia-actions/julia-buildpkg@v1
       - uses: julia-actions/julia-runtest@v1
       - uses: julia-actions/julia-processcoverage@v1

.github/workflows/prprecommit.yml

@@ -0,0 +1,39 @@
+name: PR Pre-Commit Bot
+env:
+  JULIA_NUM_THREADS: 2
+concurrency:
+  # group by workflow and ref; the last slightly strange component ensures that for pull
+  # requests, we limit to 1 concurrent job, but for the master branch we don't
+  group: ${{ github.workflow }}-${{ github.ref }}-${{ (github.ref != 'refs/heads/master' && github.ref != 'refs/heads/main') || github.run_number }}
+  # Cancel intermediate builds, but only if it is a pull request build.
+  cancel-in-progress: ${{ startsWith(github.ref, 'refs/pull/') }}
+on:
+  pull_request:
+    branches: ["master", "main"]
+jobs:
+  pre-commit:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+      with:
+        ref: ${{ github.head_ref }}
+    - name: Setup Julia
+      uses: julia-actions/setup-julia@v2
+      with:
+        version: '1'
+    - uses: julia-actions/cache@v2
+    - name: Setup JuliaFormatter
+      run: |
+        julia -e '
+          using Pkg
+          Pkg.add(name="JuliaFormatter", version="1.0.62")'
+    - name: Setup Python
+      uses: actions/setup-python@v3
+    - name: Run pre-commit
+      uses: pre-commit/[email protected]
+      continue-on-error: true
+    - name: Potentially commit changes
+      uses: stefanzweifel/git-auto-commit-action@v5
+      with:
+        commit_message: linter bot commit -- feel free to overwrite

.pre-commit-config.yaml

@@ -0,0 +1,5 @@
+repos:
+- repo: "https://github.com/domluna/JuliaFormatter.jl"
+  rev: "v1.0.62"
+  hooks:
+  - id: "julia-formatter"

src/core.jl

@@ -48,7 +48,7 @@ add_vertices!(g::AbstractGraph, n::Integer) = sum([add_vertex!(g) for i in 1:n])
     indegree(g[, v])
 
 Return a vector containing the indegrees of every vertex of the graph `g`, where
-the indegree of a vertex is defined as the number of edges which end at that 
+the indegree of a vertex is defined as the number of edges which end at that
 vertex. If `v` is specified and is a single vertex, only return the indegree of
 `v`. If `v` is specified and is a vector of vertices, only return the indegrees
 of the vertices in `v`.
@@ -85,7 +85,7 @@ indegree(g::AbstractGraph, vs=vertices(g)) = [indegree(g, x) for x in vs]
     outdegree(g[, v])
 
 Return a vector containing the outdegrees of every vertex of the graph `g`, where
-the outdegree of a vertex is defined as the number of edges which start at that 
+the outdegree of a vertex is defined as the number of edges which start at that
 vertex. If `v` is specified and is a single vertex, only return the outdegree of
 `v`. If `v` is specified and is a vector of vertices, only return the outdegrees
 of the vertices in `v`.
@@ -124,7 +124,7 @@ outdegree(g::AbstractGraph, vs=vertices(g)) = [outdegree(g, x) for x in vs]
 Return a vector containing the degrees of every vertex of the graph `g`, where
 the degree of a vertex is defined as the number of edges which start or end at
 that vertex. For directed graphs, the degree of a vertex is equal to the sum of
-its indegree and outdegree. If `v` is specified and is a single vertex, only 
+its indegree and outdegree. If `v` is specified and is a single vertex, only
 return the degree of `v`. If `v` is specified and is a vector of vertices, only
 return the degrees of the vertices in `v`.