fix: code coverage calculation improvements (#164)

.github/workflows/main.yml

@@ -45,7 +45,9 @@ jobs:
 
       - name: generate code coverage
         timeout-minutes: 4
-        run: flutter test --dart-define=IS_CI=true --coverage --coverage-path=coverage/main.lcov.info
+        run: |
+          flutter test --dart-define=IS_CI=true --coverage --coverage-path=coverage/main.lcov.info
+          lcov --remove coverage/main.lcov.info 'lib/*/*.g.dart' 'lib/generated_assets/*.dart' 'lib/*/*.gen.dart' 'lib/generated_plugin_registrant.dart'
 
       - uses: stefanzweifel/git-auto-commit-action@v4
         with:

.github/workflows/pull-request.yml

@@ -47,17 +47,19 @@ jobs:
 
       - name: unit tests
         timeout-minutes: 4
-        run: flutter test --dart-define=IS_CI=true --coverage --coverage-path=coverage/lcov.info
+        run: |
+          flutter test --dart-define=IS_CI=true --coverage --coverage-path=coverage/lcov.info
+          lcov --remove coverage/lcov.info 'lib/*/*.g.dart' 'lib/generated_assets/*.dart' 'lib/*/*.gen.dart' 'lib/generated_plugin_registrant.dart'
 
       - name: read coverage percentage
         run: |
-          echo "BASE_COVERAGE=$(lcov --summary coverage/main.lcov.info | sed -n '3p' | sed -r 's/(.+): (.+)(\%.+)/\2/' | cat)" >> $GITHUB_ENV
-          echo "THIS_COVERAGE=$(lcov --summary coverage/lcov.info | sed -n '3p' | sed -r 's/(.+): (.+)(\%.+)/\2/' | cat)" >> $GITHUB_ENV
-          echo $BASE_COVERAGE
+          echo "BASE_COVERAGE=$(dart coverage/get_coverage_threshold.dart main_branch_percentage)" >> $GITHUB_ENV
+          echo "THIS_COVERAGE=$(dart coverage/get_coverage_threshold.dart pr_branch_percentage)" >> $GITHUB_ENV
 
       - name: Comment PR
         uses: thollander/actions-comment-pull-request@v1
         with:
+          comment_includes: '## Code Coverage'
           message: |
             ## Code Coverage
             <table><tbody>
@@ -67,11 +69,8 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Check coverage percentage
-        uses: VeryGoodOpenSource/very_good_coverage@v1
-        with:
-          path: './coverage/lcov.info'
-          min_coverage: ${{ env.BASE_COVERAGE }}
-          exclude: 'lib/*/*.g.dart lib/generated_assets/*.dart lib/*/*.gen.dart lib/generated_plugin_registrant.dart'
+        run: |
+          dart coverage/get_coverage_threshold.dart check_percentage
 
       - uses: actions/upload-artifact@v2
         name: upload screenshot test failures

.gitignore

@@ -87,5 +87,6 @@ android/.idea
 
 # TEST COVERAGE
 coverage/**/*
+!coverage/**/*.dart
 test/coverage_helper_test.dart
 !coverage/main.lcov.info

coverage/get_coverage_threshold.dart

@@ -0,0 +1,51 @@
+// ignore_for_file: avoid_print
+import 'dart:io';
+
+const mainLcov = 'coverage/main.lcov.info';
+const prLcov = 'coverage/lcov.info';
+
+Future<void> main(List<String> args) async {
+  switch (args[0]) {
+    case 'main_branch_percentage':
+      print((await _calculateCoveragePercentage(mainLcov)).toStringAsFixed(2));
+      return;
+    case 'pr_branch_percentage':
+      print((await _calculateCoveragePercentage(prLcov)).toStringAsFixed(2));
+      return;
+    case 'check_percentage':
+    default:
+      await _checkCoveragePercentage();
+      return;
+  }
+}
+
+Future<void> _checkCoveragePercentage() async {
+  final mainPercentage = await _calculateCoveragePercentage(mainLcov);
+
+  final prPercentage = await _calculateCoveragePercentage(prLcov);
+  print(
+    "\n\nmain branch' test coverage percentage: ${mainPercentage.toStringAsFixed(2)}\n"
+    "pr branch' test coverage percentage:  ${prPercentage.toStringAsFixed(2)}\n\n",
+  );
+  if (prPercentage < mainPercentage) {
+    throw '\n\n!!ERROR!!\n\nThe test coverage percentage in this pull request is lower than the one on the target branch.\n\n';
+  }
+}
+
+Future<double> _calculateCoveragePercentage(String lcovFile) async {
+  final lines = await File(lcovFile).readAsLines();
+  final coverage = lines.fold<List<int>>([0, 0], (data, line) {
+    var testedLines = data[0];
+    var totalLines = data[1];
+    if (line.startsWith('DA')) {
+      totalLines++;
+      if (!line.endsWith('0')) {
+        testedLines++;
+      }
+    }
+    return [testedLines, totalLines];
+  });
+  final testedLines = coverage[0];
+  final totalLines = coverage[1];
+  return testedLines / totalLines * 100;
+}