Use GitHub API to obtain PR diff (#65)

Author: vearutop

templates/github/workflows/test-integration.yml

@@ -78,8 +78,9 @@ jobs:
           curl -sLO https://github.com/vearutop/gocovdiff/releases/download/v1.4.2/linux_amd64.tar.gz && tar xf linux_amd64.tar.gz && rm linux_amd64.tar.gz
           gocovdiff_hash=$(git hash-object ./gocovdiff)
           [ "$gocovdiff_hash" == "c37862c73a677e5a9c069470287823ab5bbf0244" ] || (echo "::error::unexpected hash for gocovdiff, possible tampering: $gocovdiff_hash" && exit 1)
-          git fetch origin master ${{ github.event.pull_request.base.sha }}
-          REP=$(./gocovdiff -cov integration.coverprofile -gha-annotations gha-integration.txt -delta-cov-file delta-cov-integration.txt -target-delta-cov ${TARGET_DELTA_COV})
+          # Fetch PR diff from GitHub API.
+          curl -s -H "Authorization: token ${{ secrets.GITHUB_TOKEN }}" -H "Accept: application/vnd.github.v3.diff" https://api.github.com/repos/${{ github.repository }}/pulls/${{ github.event.pull_request.number }} > pull_request.diff
+          REP=$(./gocovdiff -diff pull_request.diff -mod github.com/$GITHUB_REPOSITORY -cov integration.coverprofile -gha-annotations gha-integration.txt -delta-cov-file delta-cov-integration.txt -target-delta-cov ${TARGET_DELTA_COV})
           echo "${REP}"
           cat gha-integration.txt
           DIFF=$(test -e integration-base.txt && ./gocovdiff -func-cov integration.txt -func-base-cov integration-base.txt || echo "Missing base coverage file")

templates/github/workflows/test-unit.yml

@@ -80,8 +80,9 @@ jobs:
           curl -sLO https://github.com/vearutop/gocovdiff/releases/download/v1.4.2/linux_amd64.tar.gz && tar xf linux_amd64.tar.gz && rm linux_amd64.tar.gz
           gocovdiff_hash=$(git hash-object ./gocovdiff)
           [ "$gocovdiff_hash" == "c37862c73a677e5a9c069470287823ab5bbf0244" ] || (echo "::error::unexpected hash for gocovdiff, possible tampering: $gocovdiff_hash" && exit 1)
-          git fetch origin master ${{ github.event.pull_request.base.sha }}
-          REP=$(./gocovdiff -mod github.com/$GITHUB_REPOSITORY -cov unit.coverprofile -gha-annotations gha-unit.txt -delta-cov-file delta-cov-unit.txt -target-delta-cov ${TARGET_DELTA_COV})
+          # Fetch PR diff from GitHub API.
+          curl -s -H "Authorization: token ${{ secrets.GITHUB_TOKEN }}" -H "Accept: application/vnd.github.v3.diff" https://api.github.com/repos/${{ github.repository }}/pulls/${{ github.event.pull_request.number }} > pull_request.diff
+          REP=$(./gocovdiff -diff pull_request.diff -mod github.com/$GITHUB_REPOSITORY -cov unit.coverprofile -gha-annotations gha-unit.txt -delta-cov-file delta-cov-unit.txt -target-delta-cov ${TARGET_DELTA_COV})
           echo "${REP}"
           cat gha-unit.txt
           DIFF=$(test -e unit-base.txt && ./gocovdiff -mod github.com/$GITHUB_REPOSITORY -func-cov unit.txt -func-base-cov unit-base.txt || echo "Missing base coverage file")