chore: add pr code coverage to ci (#4643)

ci/partials/code-coverage-diff.yml

@@ -0,0 +1,8 @@
+platform: linux
+inputs:
+  - name: src
+  - name: pages-pipeline-tasks
+outputs: [name: src]
+run:
+  dir: src
+  path: ci/tasks/code-coverage-diff.sh

ci/pipeline.yml

@@ -75,6 +75,17 @@ jobs:
         instance_vars:
           deploy-env: ((deploy-env))
 
+  #@ if/end env == 'dev':
+  - name: code-coverage-diff
+    plan:
+      - get: src
+        trigger: true
+      - get: general-task
+      - get: pipeline-tasks
+      - task: code-coverage-diff
+        image: general-task
+        file: src/ci/partials/code-coverage-diff.yml
+
   #@ if/end env == 'staging':
   - name: update-release-branch
     plan:

ci/tasks/code-coverage-diff.sh

@@ -0,0 +1,25 @@
+#!/bin/bash
+
+set -e
+
+source "${BASH_SOURCE%/*/*}/pages-pipeline-tasks/github-setup.sh"
+
+# note our branch
+branch=$(git rev-parse --abbrev-ref HEAD)
+
+# generate test coverage
+cov_cmd="yarn test:rtl --coverageReporters json-summary --coverageDirectory tmp"
+tot_cmd="jq '.["total"]["lines"]["pct"]' tmp/coverage-summary.json"
+bash -c $cov_cmd
+newcc=$(bash -c $tot_cmd)
+git checkout main
+bash -c $cov_cmd
+oldcc=$(bash -c $tot_cmd)
+
+difcc=$(($newcc-$oldcc))
+
+gh pr comment $branch -b " \
+  ## :robot: This is an automated code coverage report
+  Total coverage (lines): $newcc%
+  Coverage diff: $diffcc%
+"