debug: misc improvements to debugging

Makefile

@@ -15,15 +15,18 @@ help:					## Show this help.
 	@echo Available targets:
 	@awk -F ':.*##' '/^[^: ]+:.*##/{printf "  \033[1m%-20s\033[m %s\n",$$1,$$2} /^##@/{printf "\n%s\n",substr($$0,5)}' $(MAKEFILE_LIST)
 
-clean_platform:
+_clean_platform:
 	@rm -f *.so */*.so
 	@rm -f *.pyd */*.pyd
 	@rm -rf __pycache__ */__pycache__ */*/__pycache__ */*/*/__pycache__ */*/*/*/__pycache__ */*/*/*/*/__pycache__
 	@rm -f *.pyc */*.pyc */*/*.pyc */*/*/*.pyc */*/*/*/*.pyc */*/*/*/*/*.pyc
 	@rm -f *.pyo */*.pyo */*/*.pyo */*/*/*.pyo */*/*/*/*.pyo */*/*/*/*/*.pyo
 	@rm -f *$$py.class */*$$py.class */*/*$$py.class */*/*/*$$py.class */*/*/*/*$$py.class */*/*/*/*/*$$py.class
 
-clean: clean_platform			## Remove artifacts of test execution, installation, etc.
+debug_clean:				## Delete various debugging artifacts.
+	@rm -rf /tmp/dis $$COVERAGE_DEBUG_FILE
+
+clean: debug_clean _clean_platform	## Remove artifacts of test execution, installation, etc.
 	@echo "Cleaning..."
 	@-pip uninstall -yq coverage
 	@mkdir -p build	# so the chmod won't fail if build doesn't exist

coverage/config.py

@@ -600,11 +600,11 @@ def read_coverage_config(
             if specified_file:
                 raise ConfigError(f"Couldn't read {fname!r} as a config file")
 
-    # $set_env.py: COVERAGE_DEBUG - Options for --debug.
     # 3) from environment variables:
     env_data_file = os.getenv("COVERAGE_FILE")
     if env_data_file:
         config.data_file = env_data_file
+    # $set_env.py: COVERAGE_DEBUG - Debug options: https://coverage.rtfd.io/cmd.html#debug
     debugs = os.getenv("COVERAGE_DEBUG")
     if debugs:
         config.debug.extend(d.strip() for d in debugs.split(","))

coverage/debug.py

@@ -446,6 +446,7 @@ def get_one(
             if file_name is not None:
                 fileobj = open(file_name, "a", encoding="utf-8")
             else:
+                # $set_env.py: COVERAGE_DEBUG_FILE - Where to write debug output
                 file_name = os.getenv("COVERAGE_DEBUG_FILE", FORCED_DEBUG_FILE)
                 if file_name in ("stdout", "stderr"):
                     fileobj = getattr(sys, file_name)

lab/pick.py

@@ -17,15 +17,15 @@
 
 as in::
 
-    te py311 -- -vvv -n 0 --select-cmd="python lab/pick.py sample 10 < tests.txt"
+    te py311 -- -vvv -n 0 --cache-clear --select-cmd="python lab/pick.py sample 10 < tests.txt"
 
 or::
 
-    for n in 1 1 2 2 3 3; do te py311 -- -vvv -n 0 --select-cmd="python lab/pick.py sample 3 $n < tests.txt"; done
+    for n in 1 1 2 2 3 3; do te py311 -- -vvv -n 0 --cache-clear --select-cmd="python lab/pick.py sample 3 $n < tests.txt"; done
 
 or::
 
-    for n in $(seq 1 10); do echo seed=$n; COVERAGE_COVERAGE=yes te py311 -- -n 0 --select-cmd="python lab/pick.py sample 20 $n < tests.txt"; done
+    for n in $(seq 1 10); do echo seed=$n; COVERAGE_COVERAGE=yes te py311 -- -n 0 --cache-clear --select-cmd="python lab/pick.py sample 20 $n < tests.txt"; done
 
 """