ci: enable code coverage

Change-Id: I1fb68bc05b1a4a75c249a11c87fd6139c1700e75

.jenkins.d/00-deps.sh

@@ -27,4 +27,8 @@ elif has Ubuntu $NODE_LABELS; then
     sudo apt-get -qq update
     sudo apt-get -qy install build-essential pkg-config python3-minimal \
                              libboost-all-dev libssl-dev libsqlite3-dev
+
+    if [[ $JOB_NAME == *"code-coverage" ]]; then
+        sudo apt-get -qy install gcovr lcov
+    fi
 fi

.jenkins.d/30-coverage.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+set -ex
+
+if [[ $JOB_NAME == *"code-coverage" ]]; then
+    lcov --quiet \
+         --capture \
+         --directory . \
+         --no-external \
+         --rc lcov_branch_coverage=1 \
+         --output-file build/coverage-with-tests.info
+
+    lcov --quiet \
+         --remove build/coverage-with-tests.info "$PWD/tests/*" \
+         --rc lcov_branch_coverage=1 \
+         --output-file build/coverage.info
+
+    genhtml --branch-coverage \
+            --demangle-cpp \
+            --legend \
+            --output-directory build/coverage \
+            --title "PSync unit tests" \
+            build/coverage.info
+fi

.travis.yml

@@ -24,6 +24,7 @@ jobs:
     - env: COMPILER=clang++-8
     - env: COMPILER=clang++-10
     - env: COMPILER=clang++-11
+    - env: COMPILER=clang++-12
 
     # macOS
     - os: osx
@@ -47,7 +48,7 @@ jobs:
 
   allow_failures:
     - arch: s390x # bug 4818
-    - env: COMPILER=clang++-11
+    - env: COMPILER=clang++-12
 
   fast_finish: true
 
@@ -64,7 +65,7 @@ before_install:
         # https://apt.llvm.org/
         LLVM_REPO=${COMPILER/clang++/llvm-toolchain-${TRAVIS_DIST}}
         travis_retry wget -nv -O - "https://apt.llvm.org/llvm-snapshot.gpg.key" | sudo apt-key add -
-        travis_retry sudo add-apt-repository -y "deb http://apt.llvm.org/${TRAVIS_DIST}/ ${LLVM_REPO%-11} main"
+        travis_retry sudo add-apt-repository -y "deb http://apt.llvm.org/${TRAVIS_DIST}/ ${LLVM_REPO%-12} main"
         travis_retry sudo apt-get -qq update
         ;;
     esac