Add test coverage reporting (#162)

Adds test coverage reporting to the Chiquito project.


## Demo
Check out the code coverage report on my fork
https://app.codecov.io/github/nullbitx8/chiquito  

Check out my fork to see how the `Rust` workflow in the project's Github
Actions now runs tests with coverage reporting.

https://github.com/nullbitx8/chiquito/actions/runs/6653135943/job/18078525896

It looks like Chiquito already has a codecov access token, so we can
already see the results here

https://app.codecov.io/github/privacy-scaling-explorations/chiquito/tree/add-test-coverage-reporting

.github/workflows/rust.yml

@@ -8,6 +8,7 @@ on:
 
 env:
   CARGO_TERM_COLOR: always
+  CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
 
 jobs:
   skip_check:
@@ -30,7 +31,12 @@ jobs:
     - name: Build
       run: cargo build --verbose
     - name: Run tests
-      run: cargo test --verbose
+      run: make test
+    - name: Upload coverage reports to Codecov
+      run: |
+        curl -o target/test_coverage/codecov -Os https://uploader.codecov.io/latest/linux/codecov
+        chmod +x target/test_coverage/codecov
+        ./target/test_coverage/codecov -t ${CODECOV_TOKEN}
 
   clippy_check:
     needs: [skip_check]

Makefile

@@ -8,4 +8,24 @@ build:
 	cargo build
 	maturin develop
 
-.PHONY: precommit build
+test:
+	# clean test coverage directory
+	rm -rf ./target/test_coverage
+	mkdir -p ./target/test_coverage
+
+	# install dependencies
+	rustup component add llvm-tools-preview
+	curl -sL https://github.com/mozilla/grcov/releases/download/v0.8.10/grcov-x86_64-unknown-linux-gnu.tar.bz2 | tar jxf - -C "./target/test_coverage"
+	chmod +x ./target/test_coverage/grcov
+
+	# run tests
+	CARGO_INCREMENTAL=0 RUSTFLAGS='-Cinstrument-coverage' LLVM_PROFILE_FILE='target/test_coverage/profraw/cargo-test-%p-%m.profraw' cargo test --verbose
+
+	# generate html coverage report
+	./target/test_coverage/grcov . --binary-path ./target/debug/deps/ -s . -t html --branch --ignore-not-existing --ignore '../*' --ignore "/*" -o target/test_coverage/html
+
+	# generate lcov coverage report
+	./target/test_coverage/grcov . --binary-path ./target/debug/deps/ -s . -t lcov --branch --ignore-not-existing --ignore '../*' --ignore "/*" -o target/test_coverage/tests.lcov
+
+
+.PHONY: precommit build test