Add comprehensive ERT test suite and fix critical bugs

Session 1: Testing infrastructure and initial test coverage

Bug fixes in wttrin.el:
- Fix wttrin-additional-url-params to handle nil unit system
- Remove incorrect callback parameter to url-retrieve-synchronously
- Add nil buffer check for network failures
- Strip HTTP headers before decoding response
- Kill buffer after fetch to prevent memory leaks
- Fix double concatenation of URL params in cache function
- Add proper URL encoding via new wttrin--build-url function

Refactoring:
- Extract wttrin--build-url as pure, testable function
- Separate URL building logic from network I/O

Test infrastructure (33 tests, 100% passing):
- tests/testutil-wttrin.el: Shared test utilities
- tests/test-wttrin-additional-url-params.el: 7 tests
- tests/test-wttrin--make-cache-key.el: 9 tests
- tests/test-wttrin--build-url.el: 10 tests
- tests/test-wttrin--cleanup-cache-if-needed.el: 7 tests

Documentation:
- docs/testing-plan.org: Comprehensive testing roadmap
- docs/bugs.org: Bug analysis from code review
- docs/NOTES.org: Session tracking and guidelines
- docs/session-1-summary.org: Detailed session summary

Next session: Cache workflow tests, parsing logic extraction, integration tests

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

1 files changed, 83 insertions, 0 deletions

diff --git a/tests/testutil-wttrin.el b/tests/testutil-wttrin.el
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+;;; testutil-wttrin.el --- Test utilities for wttrin -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2025 Craig Jennings
+
+;;; Commentary:
+
+;; Shared test utilities for wttrin test suite.
+;; Provides helper functions, fixtures, and common setup/teardown functionality.
+
+;;; Code:
+
+(require 'ert)
+
+;;; Test Data Fixtures
+
+(defconst testutil-wttrin-sample-weather-response
+  "Weather report: Paris, France
+
+     \\  /       Partly cloudy
+   _ /\"\".-. 22 °C
+     \\_(   ).  ↓ 15 km/h
+     /(___(__)  10 km
+                0.0 mm"
+  "Sample weather response for testing parsing logic.")
+
+(defconst testutil-wttrin-sample-error-response
+  "ERROR: Unknown location; please try ~curl wttr.in/:help"
+  "Sample error response from wttr.in service.")
+
+;;; Cache Testing Helpers
+
+(defun testutil-wttrin-clear-cache ()
+  "Clear the wttrin cache for test isolation."
+  (clrhash wttrin--cache))
+
+(defun testutil-wttrin-add-to-cache (location data &optional age-seconds)
+  "Add DATA to cache for LOCATION, optionally aged by AGE-SECONDS."
+  (let* ((cache-key (wttrin--make-cache-key location))
+         (timestamp (if age-seconds
+                        (- (float-time) age-seconds)
+                      (float-time))))
+    (puthash cache-key (cons timestamp data) wttrin--cache)))
+
+(defun testutil-wttrin-cache-size ()
+  "Return the current number of entries in the cache."
+  (hash-table-count wttrin--cache))
+
+;;; Custom Variable Management
+
+(defmacro testutil-wttrin-with-unit-system (unit-system &rest body)
+  "Execute BODY with wttrin-unit-system temporarily set to UNIT-SYSTEM."
+  (declare (indent 1))
+  `(let ((wttrin-unit-system ,unit-system))
+     ,@body))
+
+(defmacro testutil-wttrin-with-cache-ttl (ttl &rest body)
+  "Execute BODY with wttrin-cache-ttl temporarily set to TTL."
+  (declare (indent 1))
+  `(let ((wttrin-cache-ttl ,ttl))
+     ,@body))
+
+(defmacro testutil-wttrin-with-cache-max (max-entries &rest body)
+  "Execute BODY with wttrin-cache-max-entries temporarily set to MAX-ENTRIES."
+  (declare (indent 1))
+  `(let ((wttrin-cache-max-entries ,max-entries))
+     ,@body))
+
+;;; Test Setup and Teardown
+
+(defun testutil-wttrin-setup ()
+  "Common setup for wttrin tests.
+Call this at the beginning of each test."
+  (testutil-wttrin-clear-cache)
+  (setq wttrin--force-refresh nil))
+
+(defun testutil-wttrin-teardown ()
+  "Common teardown for wttrin tests.
+Call this at the end of each test."
+  (testutil-wttrin-clear-cache)
+  (setq wttrin--force-refresh nil))
+
+(provide 'testutil-wttrin)
+;;; testutil-wttrin.el ends here