Add scripts to run code coverage

One script to run coverage for the whole smoke test suite,
the resulting file can be uploaded to codecov.io for consumption:
https://codecov.io/gh/denniskempin/crosvm

Another script to run tests + coverage for a single crate,
which is useful during development to keep track of coverage
while adding tests (IDEs can display the generated lcov.info file)

BUG=b:171082843
TEST=Manual testing of both scripts

Change-Id: I52384762400a146cb0e7deb3d54dccf59b6134db
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/2492914
Reviewed-by: Zach Reizner <zachr@chromium.org>
Commit-Queue: Dennis Kempin <denniskempin@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Auto-Submit: Dennis Kempin <denniskempin@google.com>

.gitignore

@@ -4,3 +4,4 @@ target/
 **/*.orig
 **/Cargo.lock
 !/Cargo.lock
+lcov.info

bin/crate_coverage

@@ -0,0 +1,36 @@
+#!/bin/bash
+# Copyright 2020 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+#
+# Calculates coverage for the specified crate only
+# Usage:
+# $ ./bin/crate_coverage arch [additional arguments for cargo test]
+# Requirements:
+# $ rustup toolchain install nightly
+# $ cargo install grcov rust-covfix
+set -ex
+cd "${0%/*}/../"
+
+target_dir=$(
+    cargo metadata --no-deps --format-version 1 |
+        jq -r ".target_directory"
+)
+
+# Delete old coverage profiles
+find "$target_dir/debug" -name "*.gcda" -delete
+
+# Run test with coverage profiling
+(cd $1 && CARGO_INCREMENTAL=0 \
+    RUSTFLAGS="-Zprofile -Ccodegen-units=1 -Copt-level=0 -Coverflow-checks=off \
+-Zpanic_abort_tests" \
+    cargo +nightly test "${@:2}")
+
+# Calculate code coverage
+grcov "$target_dir/debug" -s . \
+    --ignore "/*" --ignore-not-existing \
+    -t lcov --llvm --branch \
+    -o /tmp/lcov.info
+
+# Apply code coverage fixes
+rust-covfix /tmp/lcov.info >lcov.info

bin/smoke_test_coverage

@@ -0,0 +1,39 @@
+#!/bin/bash
+# Copyright 2020 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+#
+# Calculates test coverage of all unit tests in crosvm.
+# Requirements:
+# $ apt install jq
+# $ rustup toolchain install nightly
+# $ cargo install grcov rust-covfix
+set -ex
+cd "${0%/*}/../"
+
+target_dir=$(
+    cargo metadata --no-deps --format-version 1 |
+        jq -r ".target_directory"
+)
+
+# Delete old coverage profiles
+find "$target_dir/debug" -name "*.gcda" -delete
+
+# Run --all tests with coverage profiling options enabled.
+CARGO_INCREMENTAL=0 \
+    RUSTFLAGS="-Zprofile -Ccodegen-units=1 -Copt-level=0 -Coverflow-checks=off \
+-Zpanic_abort_tests" \
+    cargo +nightly test \
+    --no-fail-fast --features default-no-sandbox,wl-dmabuf,gpu,tpm \
+    --all --exclude aarch64 \
+    -- \
+    --test-threads=1
+
+# Calculate code coverage
+grcov "$target_dir/debug" -s . \
+    --ignore "/*" --ignore-not-existing \
+    -t lcov --llvm --branch \
+    -o /tmp/lcov.info
+
+# Apply code coverage fixes
+rust-covfix /tmp/lcov.info >lcov.info