test: refactor coverage logic

BUILDING.md

@@ -389,28 +389,32 @@ $ make coverage
 ```
 
 A detailed coverage report will be written to `coverage/index.html` for
-JavaScript coverage and to `coverage/cxxcoverage.html` for C++ coverage
-(if you only want to run the JavaScript tests then you do not need to run
-the first command `./configure --coverage`).
+JavaScript coverage and to `coverage/cxxcoverage.html` for C++ coverage.
 
-_Generating a test coverage report can take several minutes._
-
-To collect coverage for a subset of tests you can set the `CI_JS_SUITES` and
-`CI_NATIVE_SUITES` variables (to run specific suites, e.g., `child-process`, in
-isolation, unset the opposing `_SUITES` variable):
+If you only want to run the JavaScript tests then you do not need to run
+the first command (`./configure --coverage`). Run `make coverage-run-js`,
+to execute JavaScript tests independently of the C++ test suite:
 
 ```text
-$ CI_JS_SUITES=child-process CI_NATIVE_SUITES= make coverage
+$ make coverage-run-js
 ```
 
-The above command executes tests for the `child-process` subsystem and
-outputs the resulting coverage report.
+If you are updating tests and want to collect coverrage for a single test file
+(e.g. `test/parallel/test-stream2-transform.js`):
+
+```text
+$ make coverage-clean
+$ NODE_V8_COVERAGE=coverage/tmp python tools/test.py test/parallel/test-stream2-transform.js
+$ make coverage-report-js
+```
 
-Alternatively, you can run `make coverage-run-js`, to execute JavaScript tests
-independently of the C++ test suite:
+You can collect coverage for the entire suite of tests for a given subsystem
+by providing the name of a subsystem:
 
 ```text
-$ CI_JS_SUITES=fs CI_NATIVE_SUITES= make coverage-run-js
+$ make coverage-clean
+$ NODE_V8_COVERAGE=coverage/tmp python tools/test.py -J --mode=release child-process
+$ make coverage-report-js
 ```
 
 The `make coverage` command downloads some tools to the project root directory.

Makefile

@@ -197,20 +197,11 @@ check: test
 # Remove files generated by running coverage, put the non-instrumented lib back
 # in place
 coverage-clean:
-	if [ -d lib_ ]; then $(RM) -r lib; mv lib_ lib; fi
 	$(RM) -r node_modules
 	$(RM) -r gcovr build
-	$(RM) -r out/$(BUILDTYPE)/.coverage
-	$(RM) out/$(BUILDTYPE)/obj.target/node/gen/*.gcda
-	$(RM) out/$(BUILDTYPE)/obj.target/node/src/*.gcda
-	$(RM) out/$(BUILDTYPE)/obj.target/node/src/tracing/*.gcda
-	$(RM) out/$(BUILDTYPE)/obj.target/node/gen/*.gcno
-	$(RM) out/$(BUILDTYPE)/obj.target/node/src/*.gcno
-	$(RM) out/$(BUILDTYPE)/obj.target/node/src/tracing/*.gcno
-	$(RM) out/$(BUILDTYPE)/obj.target/cctest/src/*.gcno
-	$(RM) out/$(BUILDTYPE)/obj.target/cctest/test/cctest/*.gcno
-	$(RM) out/$(BUILDTYPE)/obj.target/embedtest/src/*.gcno
-	$(RM) out/$(BUILDTYPE)/obj.target/embedtest/test/embedding/*.gcno
+	$(RM) -r coverage/tmp
+	$(FIND) out/$(BUILDTYPE)/obj.target \( -name "*.gcda" -o -name "*.gcno" \) \
+		-type f -exec $(RM) {} \;
 
 .PHONY: coverage
 # Build and test with code coverage reporting.  Leave the lib directory
@@ -245,8 +236,8 @@ coverage-test: coverage-build
 	$(RM) out/$(BUILDTYPE)/obj.target/node/src/*/*.gcda
 	$(RM) out/$(BUILDTYPE)/obj.target/node_lib/src/*.gcda
 	$(RM) out/$(BUILDTYPE)/obj.target/node_lib/src/*/*.gcda
-	-NODE_V8_COVERAGE=out/$(BUILDTYPE)/.coverage \
-								TEST_CI_ARGS="$(TEST_CI_ARGS) --type=coverage" $(MAKE) $(COVTESTS)
+	-NODE_V8_COVERAGE=coverage/tmp \
+		TEST_CI_ARGS="$(TEST_CI_ARGS) --type=coverage" $(MAKE) $(COVTESTS)
 	$(MAKE) coverage-report-js
 	-(cd out && "../gcovr/scripts/gcovr" \
 		--gcov-exclude='.*\b(deps|usr|out|cctest|embedding)\b' -v \
@@ -259,17 +250,10 @@ coverage-test: coverage-build
 	@grep -A3 Lines coverage/cxxcoverage.html | grep style  \
 		| sed 's/<[^>]*>//g'| sed 's/ //g'
 
-COV_REPORT_OPTIONS = --reporter=html \
-	--temp-directory=out/$(BUILDTYPE)/.coverage --omit-relative=false \
-	--resolve=./lib --exclude="benchmark/" --exclude="deps/" --exclude="test/" --exclude="tools/" \
-	--wrapper-length=0
-ifdef COV_ENFORCE_THRESHOLD
-	COV_REPORT_OPTIONS += --check-coverage --lines=$(COV_ENFORCE_THRESHOLD)
-endif
-
 .PHONY: coverage-report-js
 coverage-report-js:
-	$(NODE) ./node_modules/.bin/c8 report $(COV_REPORT_OPTIONS)
+	-$(MAKE) coverage-build-js
+	$(NODE) ./node_modules/.bin/c8 report
 
 .PHONY: cctest
 # Runs the C++ tests using the built `cctest` executable.
@@ -305,9 +289,8 @@ tooltest:
 
 .PHONY: coverage-run-js
 coverage-run-js:
-	$(RM) -r out/$(BUILDTYPE)/.coverage
-	$(MAKE) coverage-build-js
-	-NODE_V8_COVERAGE=out/$(BUILDTYPE)/.coverage CI_SKIP_TESTS=$(COV_SKIP_TESTS) \
+	$(RM) -r coverage/tmp
+	-NODE_V8_COVERAGE=coverage/tmp CI_SKIP_TESTS=$(COV_SKIP_TESTS) \
 					TEST_CI_ARGS="$(TEST_CI_ARGS) --type=coverage" $(MAKE) jstest
 	$(MAKE) coverage-report-js