feat(dev-fkeys): add F6 test runner menu (Phase 2a)

I extended `dev-fkeys.el` with the F6 dispatcher half of the spec. F6 prompts via `completing-read` between two candidates: "All tests" delegates to `projectile-test-project`, and "Current file's tests" detects the buffer's language by extension, derives the runner command, and pipes through `compile' from the projectile root. C-F6 is the fast path straight to "Current file's tests".

Per-language coverage:

- Elisp source files map to `make test-name TEST=^test-<stem>-`. Elisp test files run with `make test-file FILE=<rel-path>` so a per-helper file like `test-foo--bar.el' runs only its own tests.
- Python source files map to `pytest tests/test_<stem>.py'. Python test files run with `pytest <rel-path>'.
- Go runs the package containing the file: `go test ./<rel-dir>'. Source and test files use the same command since Go test scope is per-package. Limit: this runs every `_test.go' in the package, not just the buffer's file. Phase 2b can refine via test-name discovery.
- TypeScript and JavaScript are detected but punted for v1. The runner-command builder returns nil and the orchestrator signals a user-error rather than guessing.

The F6 binding moved from the Phase 1 stopgap (`projectile-test-project') to `cj/f6-test-runner'. C-F6 is newly bound to `cj/f6-current-file-tests'. M-F6 stays unbound, reserved for Phase 2b's "Run a test..." menu entry.

TDD: 68 new tests across 7 files. Production code split into small testable internals (`cj/--f6-language-detect', `cj/--f6-buffer-is-test-file-p', `cj/--f6-source-stem', `cj/--f6-test-runner-cmd-for', `cj/--f6-current-file-tests-impl') plus two thin interactive wrappers. Smoke tests confirm bindings register on load.

I also updated the module commentary with the Phase 2b plan, the capture-then-filter approach for tree-sitter discovery, and a pointer to Emacs bug #79687. The bug is the predicate-syntax mismatch that breaks `:match' / `:equal' / `:pred' queries on Emacs 30.2 with libtree-sitter 0.26. The fix lives on Emacs master (commit b0143530), targets Emacs 31, and has not been backported to the emacs-30 branch as of today. Phase 2b will use queries without predicates and filter results in Elisp, sidestepping the issue. Mike Olson's `treesit-predicate-rewrite.el' applies the same idea to font-lock if you want it before Phase 2b lands.

1 files changed, 112 insertions, 0 deletions

diff --git a/tests/test-dev-fkeys--f6-test-runner-cmd-for.el b/tests/test-dev-fkeys--f6-test-runner-cmd-for.el
new file mode 100644
index 00000000..d9f8f464
--- /dev/null
+++ b/tests/test-dev-fkeys--f6-test-runner-cmd-for.el
@@ -0,0 +1,112 @@
+;;; test-dev-fkeys--f6-test-runner-cmd-for.el --- Tests for cj/--f6-test-runner-cmd-for -*- lexical-binding: t -*-
+
+;;; Commentary:
+;; Tests for the per-language test-runner-command builder.
+;;
+;; Inputs are five primitives the orchestrator pre-computes:
+;;
+;;   LANGUAGE        symbol from `cj/--f6-language-detect'
+;;   IS-TEST-FILE    boolean from `cj/--f6-buffer-is-test-file-p'
+;;   REL-PATH        file path relative to project root
+;;   STEM            source module stem from `cj/--f6-source-stem'
+;;   REL-DIR         file's directory relative to project root
+;;
+;; Returns a shell command string to pipe through `compile', or nil for
+;; languages we don't have a runner for. The TS / JS handlers are punted
+;; for v1 — they return nil.
+
+;;; Code:
+
+(require 'ert)
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'dev-fkeys)
+
+;;; Normal Cases — Elisp
+
+(ert-deftest test-dev-fkeys-f6-cmd-for-elisp-test-file ()
+  "Normal: an elisp test file runs via `make test-file FILE=<path>'."
+  (should (string=
+           (cj/--f6-test-runner-cmd-for
+            'elisp t "tests/test-foo.el" "foo" "tests")
+           "make test-file FILE=tests/test-foo.el")))
+
+(ert-deftest test-dev-fkeys-f6-cmd-for-elisp-source-file ()
+  "Normal: an elisp source file runs via `make test-name TEST=^test-<stem>-'.
+The trailing hyphen anchors the regex so test names from a different
+module that happen to share a prefix don't get pulled in."
+  (should (string=
+           (cj/--f6-test-runner-cmd-for
+            'elisp nil "modules/foo.el" "foo" "modules")
+           "make test-name TEST=^test-foo-")))
+
+;;; Normal Cases — Python
+
+(ert-deftest test-dev-fkeys-f6-cmd-for-python-test-file ()
+  "Normal: a Python test file runs via `pytest <rel-path>'."
+  (should (string=
+           (cj/--f6-test-runner-cmd-for
+            'python t "tests/test_foo.py" "foo" "tests")
+           "pytest tests/test_foo.py")))
+
+(ert-deftest test-dev-fkeys-f6-cmd-for-python-source-file ()
+  "Normal: a Python source file runs via `pytest tests/test_<stem>.py'."
+  (should (string=
+           (cj/--f6-test-runner-cmd-for
+            'python nil "pkg/foo.py" "foo" "pkg")
+           "pytest tests/test_foo.py")))
+
+;;; Normal Cases — Go
+
+(ert-deftest test-dev-fkeys-f6-cmd-for-go-test-file ()
+  "Normal: a Go test file runs the package via `go test ./<rel-dir>'."
+  (should (string=
+           (cj/--f6-test-runner-cmd-for
+            'go t "pkg/foo_test.go" "foo" "pkg")
+           "go test ./pkg")))
+
+(ert-deftest test-dev-fkeys-f6-cmd-for-go-source-file ()
+  "Normal: a Go source file runs the same package via `go test ./<rel-dir>'.
+Go test scope is per-package; running the source's package picks up its
+test files."
+  (should (string=
+           (cj/--f6-test-runner-cmd-for
+            'go nil "pkg/foo.go" "foo" "pkg")
+           "go test ./pkg")))
+
+;;; Boundary Cases
+
+(ert-deftest test-dev-fkeys-f6-cmd-for-elisp-test-file-with-double-dash ()
+  "Boundary: a per-helper test file runs only that file, not the whole
+test-name prefix. `make test-file FILE=...' is precise; `test-name'
+would over-match."
+  (should (string=
+           (cj/--f6-test-runner-cmd-for
+            'elisp t "tests/test-foo--bar.el" "foo" "tests")
+           "make test-file FILE=tests/test-foo--bar.el")))
+
+(ert-deftest test-dev-fkeys-f6-cmd-for-go-source-at-root ()
+  "Boundary: a Go source file at project root runs `go test ./'."
+  (should (string=
+           (cj/--f6-test-runner-cmd-for
+            'go nil "main.go" "main" "")
+           "go test ./")))
+
+;;; Error Cases
+
+(ert-deftest test-dev-fkeys-f6-cmd-for-typescript-returns-nil ()
+  "Error: TypeScript is punted for v1 and returns nil."
+  (should (null (cj/--f6-test-runner-cmd-for
+                 'typescript t "src/foo.test.ts" "foo" "src"))))
+
+(ert-deftest test-dev-fkeys-f6-cmd-for-javascript-returns-nil ()
+  "Error: JavaScript is punted for v1 and returns nil."
+  (should (null (cj/--f6-test-runner-cmd-for
+                 'javascript t "src/foo.test.js" "foo" "src"))))
+
+(ert-deftest test-dev-fkeys-f6-cmd-for-unknown-returns-nil ()
+  "Error: an unknown language returns nil."
+  (should (null (cj/--f6-test-runner-cmd-for
+                 'unknown nil "Makefile" "Makefile" ""))))
+
+(provide 'test-dev-fkeys--f6-test-runner-cmd-for)
+;;; test-dev-fkeys--f6-test-runner-cmd-for.el ends here