test: cover pure-logic gaps found by the coverage audit

I ran make coverage and worked the report function by function, separating real gaps from interactive/IO wrappers that aren't unit-test targets. These tests fill the genuine pure-logic holes: predicates, parsers, formatters, transforms, and three modules that had no test file at all.

New files cover car-member (local-repository), show-kill-insert-item (show-kill-ring), the oauth2-auto plstore cache fix (auth-config), the coverage-core project-root fallback, reconcile--dirty-p, and the recurrence-frequency dispatch in calendar-sync. Extended files add the missing branches: coverage-core's merge-base and diff /dev/null handling plus the staged and branch-vs-main scopes, the detect-system-timezone symlink path, user-constants no-op and optional-failure branches, the elfeed playlist branch with HTML-entity decoding, the duplicate-line no-comment-syntax guard, and several calendar-sync edges (exception field overrides, timestamp seconds and TZID fallback, property-line position advancement, parse-ics nil and out-of-range inputs).

Mocks sit at the real boundaries (plstore, url-retrieve, process-file, git) so each function's own logic runs. Dates come from relative helpers. About 65 tests added across 15 files, and the full suite stays green.

1 files changed, 106 insertions, 0 deletions

diff --git a/tests/test-calendar-sync--expand-recurring-event.el b/tests/test-calendar-sync--expand-recurring-event.el
new file mode 100644
index 000000000..41f0afa9c
--- /dev/null
+++ b/tests/test-calendar-sync--expand-recurring-event.el
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+;;; test-calendar-sync--expand-recurring-event.el --- Tests for recurrence dispatch -*- lexical-binding: t; -*-
+
+;;; Commentary:
+;; Tests for calendar-sync--expand-recurring-event — the dispatcher that maps
+;; an RRULE frequency to the matching expander and applies EXDATE filtering.
+;; The individual expanders, parser, and exdate helpers have their own tests;
+;; here they are stubbed at the boundary so only the dispatch and the
+;; exdate-vs-no-exdate branch are exercised.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+(require 'testutil-calendar-sync)
+(require 'calendar-sync)
+
+(defmacro test-cs-ere--with (overrides &rest body)
+  "Run BODY with the recurrence helpers stubbed.
+OVERRIDES is an extra list of cl-letf* bindings layered on the defaults:
+RRULE present, parse-event returns 'BASE, no exdates, and every expander
+errors if called (each test re-binds the one it expects).  cl-letf* is
+sequential, so a re-bound place in OVERRIDES wins over the default."
+  (declare (indent 1))
+  `(cl-letf* (((symbol-function 'calendar-sync--get-property)
+              (lambda (_e prop) (when (string= prop "RRULE") "R")))
+             ((symbol-function 'calendar-sync--parse-event) (lambda (_e) 'BASE))
+             ((symbol-function 'calendar-sync--collect-exdates) (lambda (_e) nil))
+             ((symbol-function 'calendar-sync--expand-daily)
+              (lambda (&rest _) (error "daily should not be called")))
+             ((symbol-function 'calendar-sync--expand-weekly)
+              (lambda (&rest _) (error "weekly should not be called")))
+             ((symbol-function 'calendar-sync--expand-monthly)
+              (lambda (&rest _) (error "monthly should not be called")))
+             ((symbol-function 'calendar-sync--expand-yearly)
+              (lambda (&rest _) (error "yearly should not be called")))
+             ((symbol-function 'calendar-sync--filter-exdates)
+              (lambda (&rest _) (error "filter-exdates should not be called")))
+             ,@overrides)
+     ,@body))
+
+;;; Normal Cases — frequency dispatch
+
+(ert-deftest test-calendar-sync--expand-recurring-event-dispatches-daily ()
+  "Normal: FREQ=DAILY routes to the daily expander."
+  (test-cs-ere--with
+      (((symbol-function 'calendar-sync--parse-rrule) (lambda (_r) '(:freq daily)))
+       ((symbol-function 'calendar-sync--expand-daily) (lambda (&rest _) '(DAILY))))
+    (should (equal (calendar-sync--expand-recurring-event "evt" 'range) '(DAILY)))))
+
+(ert-deftest test-calendar-sync--expand-recurring-event-dispatches-monthly ()
+  "Normal: FREQ=MONTHLY routes to the monthly expander."
+  (test-cs-ere--with
+      (((symbol-function 'calendar-sync--parse-rrule) (lambda (_r) '(:freq monthly)))
+       ((symbol-function 'calendar-sync--expand-monthly) (lambda (&rest _) '(MONTHLY))))
+    (should (equal (calendar-sync--expand-recurring-event "evt" 'range) '(MONTHLY)))))
+
+(ert-deftest test-calendar-sync--expand-recurring-event-dispatches-yearly ()
+  "Normal: FREQ=YEARLY routes to the yearly expander."
+  (test-cs-ere--with
+      (((symbol-function 'calendar-sync--parse-rrule) (lambda (_r) '(:freq yearly)))
+       ((symbol-function 'calendar-sync--expand-yearly) (lambda (&rest _) '(YEARLY))))
+    (should (equal (calendar-sync--expand-recurring-event "evt" 'range) '(YEARLY)))))
+
+;;; Boundary / Error Cases
+
+(ert-deftest test-calendar-sync--expand-recurring-event-unsupported-freq-nil ()
+  "Error: an unsupported frequency expands to nil, no expander called."
+  (test-cs-ere--with
+      (((symbol-function 'calendar-sync--parse-rrule) (lambda (_r) '(:freq hourly))))
+    (should-not (calendar-sync--expand-recurring-event "evt" 'range))))
+
+(ert-deftest test-calendar-sync--expand-recurring-event-no-rrule-nil ()
+  "Boundary: an event with no RRULE returns nil (not a recurring event)."
+  (test-cs-ere--with
+      (((symbol-function 'calendar-sync--get-property) (lambda (&rest _) nil)))
+    (should-not (calendar-sync--expand-recurring-event "evt" 'range))))
+
+(ert-deftest test-calendar-sync--expand-recurring-event-unparseable-base-nil ()
+  "Boundary: when the base event fails to parse, expansion returns nil."
+  (test-cs-ere--with
+      (((symbol-function 'calendar-sync--parse-rrule) (lambda (_r) '(:freq daily)))
+       ((symbol-function 'calendar-sync--parse-event) (lambda (_e) nil)))
+    (should-not (calendar-sync--expand-recurring-event "evt" 'range))))
+
+;;; EXDATE branch
+
+(ert-deftest test-calendar-sync--expand-recurring-event-applies-exdate-filter ()
+  "Normal: with exdates present, occurrences pass through the exdate filter."
+  (test-cs-ere--with
+      (((symbol-function 'calendar-sync--parse-rrule) (lambda (_r) '(:freq daily)))
+       ((symbol-function 'calendar-sync--expand-daily) (lambda (&rest _) '(O1 O2)))
+       ((symbol-function 'calendar-sync--collect-exdates) (lambda (_e) '(EX)))
+       ((symbol-function 'calendar-sync--filter-exdates)
+        (lambda (occs _ex) (remq 'O2 occs))))
+    (should (equal (calendar-sync--expand-recurring-event "evt" 'range) '(O1)))))
+
+(ert-deftest test-calendar-sync--expand-recurring-event-no-exdate-skips-filter ()
+  "Boundary: with no exdates, the filter is skipped and occurrences pass through."
+  (test-cs-ere--with
+      (((symbol-function 'calendar-sync--parse-rrule) (lambda (_r) '(:freq daily)))
+       ((symbol-function 'calendar-sync--expand-daily) (lambda (&rest _) '(O1 O2))))
+    ;; filter-exdates stays the error stub; it must not be called here
+    (should (equal (calendar-sync--expand-recurring-event "evt" 'range) '(O1 O2)))))
+
+(provide 'test-calendar-sync--expand-recurring-event)
+;;; test-calendar-sync--expand-recurring-event.el ends here