feat(coverage): print a terminal coverage summary from the SimpleCov report

`make coverage` only reported the JSON's file size, so reading the real number meant opening the report by hand. I added a self-contained `scripts/coverage-summary.el` that parses the SimpleCov JSON and prints per-file covered/total lines with a percent, a line-weighted project figure, and a source-weighted figure. A tracked source missing from the report counts as 0% rather than dropping out silently, so a source that never got instrumented still shows up.

A new `coverage-summary` target runs it against the last report, and `make coverage` chains it onto the tail of a local run (CI emits coveralls.json, not simplecov.json, so it's skipped there). Covered by `tests/test-pearl-coverage-summary.el`: parser hit/executable/merge-key semantics, the per-file records, and the error paths for a missing or malformed report.

1 files changed, 21 insertions, 1 deletions

diff --git a/Makefile b/Makefile
index 621cf95..3c7ab82 100644
--- a/Makefile
+++ b/Makefile
@@ -27,7 +27,7 @@ ALL_TESTS = $(filter-out $(TEST_DIR)/test-bootstrap.el, \
 
 .PHONY: help test test-all test-unit test-integration test-file test-one test-name \
         count list validate lint check-deps clean \
-        setup compile coverage coverage-clean
+        setup compile coverage coverage-summary coverage-clean
 
 help:
 	@$(MAKE) -C $(TEST_DIR) help
@@ -148,6 +148,26 @@ coverage: coverage-clean $(COVERAGE_DIR)
 		echo "[!] No coverage file produced; check that undercover is installed"; \
 		exit 1; \
 	fi
+	@# Print the human-readable summary after a local run.  CI emits
+	@# coveralls.json (not simplecov.json) and the upload action reports
+	@# instead, so skip the terminal summary there.
+	@if [ -z "$$CI" ] && [ -f $(COVERAGE_FILE) ]; then \
+		$(MAKE) --no-print-directory coverage-summary; \
+	fi
+
+# Print a human-readable summary of the SimpleCov report: per-file
+# covered/total lines + percent, a line-weighted project figure, and a
+# source-weighted figure where a tracked source missing from the report
+# counts as 0% (so an un-instrumented source shows up rather than vanishing
+# from the numbers).  Run on its own against an existing report, or
+# automatically at the tail of 'make coverage'.
+coverage-summary:
+	@if [ ! -f $(COVERAGE_FILE) ]; then \
+		echo "[!] No coverage report at $(COVERAGE_FILE). Run 'make coverage' first."; \
+		exit 1; \
+	fi
+	@$(EMACS_BATCH) -L scripts -l coverage-summary \
+		--eval '(pearl-coverage-print-summary "$(COVERAGE_FILE)" (list "$(SOURCE_FILE)") "$(CURDIR)")'
 
 coverage-clean:
 	@rm -f $(COVERAGE_FILE)