CI: Add automated test coverage reports.

.gitlab-ci.yml

@@ -35,9 +35,6 @@ variables:
     - rustc -vV
     - rustup show
     - bash --version
-    - mkdir -p ${CARGO_HOME}; touch ${CARGO_HOME}/config
-    # global RUSTFLAGS overrides the linker args so this way is better to pass the flags
-    - printf '[build]\nrustflags = ["-C", "link-dead-code"]\n' | tee ${CARGO_HOME}/config
     # if there is no directory for this $CI_COMMIT_REF_NAME/$CI_JOB_NAME
     # create such directory and
     # create hardlinks recursively of all the files from the master/$CI_JOB_NAME if it exists
@@ -113,9 +110,34 @@ test:
   needs:
     - check-std
   script:
-    - for crate in ${ALL_CRATES}; do
-        cargo test --verbose --all-features --release --manifest-path ${crate}/Cargo.toml;
-      done
+    - cargo test --verbose --all-features --no-fail-fast --release --workspace
+
+codecov:
+  stage:                           workspace
+  <<:                              *docker-env
+  needs:
+    - check-std
+  variables:
+    # According to https://github.com/mozilla/grcov/blob/master/README.md
+    # we have to use these variables.
+    CARGO_INCREMENTAL:             0
+    # If `-Zno-landing-pads` is enabled some some tests start to fail.
+    RUSTFLAGS:                     "-Zprofile -Ccodegen-units=1 -Cinline-threshold=0 -Clink-dead-code -Coverflow-checks=off"
+    # The `cargo-taurpalin` coverage reporting tool seems to have better code instrumentation
+    # and thus produces better results for Rust codebases in general. However, unlike `grcov` it
+    # requires running docker with `--security-opt seccomp=unconfined` which is why we use `grcov`
+    # instead.
+  script:
+    # RUSTFLAGS are the cause target cache can't be used here
+    - unset "CARGO_TARGET_DIR"
+    - cargo clean
+    - cargo test --verbose --all-features --no-fail-fast --workspace
+    - cargo build --verbose --all-features --workspace
+    - grcov ./target -s . -t coveralls+ --guess-directory-when-missing --llvm --branch --ignore-not-existing --ignore "/*"
+        --token "$CODECOV_TOKEN" --commit-sha "$CI_COMMIT_SHA" --output-file ccov.json
+    # We'd like to not use a remote bash script for uploading the coverage reports,
+    # however this job seems to be more tricky than we hoped.
+    - bash <(curl -s https://codecov.io/bash) -t "$CODECOV_TOKEN" -X gcov -f ccov.json
 
 clippy-std:
   stage:                           workspace