[tests] Added coverage report target 'check'

Issuing 'make check' now collects unit tests coverage data and generates
a report in HTML.

scripts/collect-coverage.sh

@@ -0,0 +1,61 @@
+#!/usr/bin/env bash
+
+set -e
+set -o pipefail
+
+function usage() {
+    echo "Error: LCOV and genhtml are required for generating coverage reports."
+    if [ `uname -s` = 'Linux' ]; then
+        echo "On Debian-based distros, you can install them via 'apt-get install lcov'"
+    elif [ `uname -s` = 'Darwin' ]; then
+        echo "On OS X, you can install them via 'brew install lcov'"
+    fi
+    exit 1
+}
+
+command -v lcov >/dev/null 2>&1 || usage
+command -v genhtml >/dev/null 2>&1 || usage
+
+# Zero coverage counters
+lcov \
+    --quiet \
+    --zerocounters \
+    --directory "build/${HOST_SLUG}/${BUILDTYPE}" \
+    --output-file "build/${HOST_SLUG}/${BUILDTYPE}/coverage.info" \
+    >/dev/null 2>&1
+
+# Run all unit tests
+./scripts/run_tests.sh "build/${HOST_SLUG}/${BUILDTYPE}/test"
+
+# Collect coverage data and save it into coverage.info
+echo "Collecting coverage data..."
+lcov \
+    --quiet \
+    --capture \
+    --no-external \
+    --directory "src/mbgl" \
+    --directory "platform" \
+    --directory "include/mbgl" \
+    --directory "build/${HOST_SLUG}/${BUILDTYPE}" \
+    --base-directory "build/${HOST_SLUG}/${BUILDTYPE}" \
+    --output-file "build/${HOST_SLUG}/${BUILDTYPE}/coverage.info" \
+    >/dev/null 2>&1
+
+# Generate HTML report based on coverage.info
+echo "Generating HTML report..."
+genhtml \
+    --quiet \
+    --show-details \
+    --keep-descriptions \
+    --function-coverage \
+    --no-branch-coverage \
+    --title "Mapbox GL Native" \
+    --num-spaces 4 \
+    --sort \
+    --demangle-cpp \
+    --prefix $(pwd -P) \
+    --output-directory "build/${HOST_SLUG}/${BUILDTYPE}/coverage" \
+    "build/${HOST_SLUG}/${BUILDTYPE}/coverage.info" \
+    >/dev/null 2>&1
+
+echo "Coverage report is now available in build/${HOST_SLUG}/${BUILDTYPE}/coverage/index.html"

scripts/main.mk

@@ -166,6 +166,9 @@ tidy: Ninja/compdb
 test-%: Makefile/test
 	./scripts/run_tests.sh "build/$(HOST_SLUG)/$(BUILDTYPE)/test" --gtest_filter=$*
 
+check: Makefile/test
+	./scripts/collect-coverage.sh
+
 #### Helper targets ############################################################
 
 .PHONY: print-env