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, 125 insertions, 0 deletions

diff --git a/tests/test-dev-fkeys--f6-current-file-tests-impl.el b/tests/test-dev-fkeys--f6-current-file-tests-impl.el
new file mode 100644
index 00000000..ecc7a4f4
--- /dev/null
+++ b/tests/test-dev-fkeys--f6-current-file-tests-impl.el
@@ -0,0 +1,125 @@
+;;; test-dev-fkeys--f6-current-file-tests-impl.el --- Tests for cj/--f6-current-file-tests-impl -*- lexical-binding: t -*-
+
+;;; Commentary:
+;; Tests for the "Current file's tests" orchestrator. Takes (FILE
+;; PROJECT-ROOT), composes the per-language test-runner command, and runs
+;; it through `compile' with `default-directory' bound to PROJECT-ROOT.
+;; Errors when no file, no project root, or no test runner is available
+;; for the file's language.
+
+;;; Code:
+
+(require 'ert)
+(require 'cl-lib)
+(add-to-list 'load-path (expand-file-name "modules" user-emacs-directory))
+(require 'dev-fkeys)
+
+;;; Normal Cases
+
+(ert-deftest test-dev-fkeys-f6-current-file-tests-impl-elisp-source ()
+  "Normal: an elisp source file runs `make test-name TEST=^test-<stem>-'.
+
+Components integrated:
+- `cj/--f6-current-file-tests-impl' (unit under test)
+- `cj/--f6-language-detect' (real)
+- `cj/--f6-source-stem' (real)
+- `cj/--f6-buffer-is-test-file-p' (real)
+- `cj/--f6-test-runner-cmd-for' (real)
+- `compile' (MOCKED — captures cmd and default-directory)"
+  (let (seen-cmd seen-dir)
+    (cl-letf (((symbol-function 'compile)
+               (lambda (cmd) (setq seen-cmd cmd
+                                   seen-dir default-directory))))
+      (cj/--f6-current-file-tests-impl
+       "/home/u/proj/modules/foo.el"
+       "/home/u/proj/")
+      (should (string= seen-cmd "make test-name TEST=^test-foo-"))
+      (should (string= (file-name-as-directory seen-dir)
+                       (file-name-as-directory "/home/u/proj/"))))))
+
+(ert-deftest test-dev-fkeys-f6-current-file-tests-impl-elisp-test-file ()
+  "Normal: an elisp test file runs `make test-file FILE=<rel-path>'."
+  (let (seen-cmd)
+    (cl-letf (((symbol-function 'compile)
+               (lambda (cmd) (setq seen-cmd cmd))))
+      (cj/--f6-current-file-tests-impl
+       "/home/u/proj/tests/test-foo.el"
+       "/home/u/proj/")
+      (should (string= seen-cmd "make test-file FILE=tests/test-foo.el")))))
+
+(ert-deftest test-dev-fkeys-f6-current-file-tests-impl-python-source ()
+  "Normal: a Python source file maps to `pytest tests/test_<stem>.py'."
+  (let (seen-cmd)
+    (cl-letf (((symbol-function 'compile)
+               (lambda (cmd) (setq seen-cmd cmd))))
+      (cj/--f6-current-file-tests-impl
+       "/home/u/proj/pkg/foo.py"
+       "/home/u/proj/")
+      (should (string= seen-cmd "pytest tests/test_foo.py")))))
+
+(ert-deftest test-dev-fkeys-f6-current-file-tests-impl-go-source ()
+  "Normal: a Go source file runs the package via `go test ./<rel-dir>'."
+  (let (seen-cmd)
+    (cl-letf (((symbol-function 'compile)
+               (lambda (cmd) (setq seen-cmd cmd))))
+      (cj/--f6-current-file-tests-impl
+       "/home/u/proj/pkg/foo.go"
+       "/home/u/proj/")
+      (should (string= seen-cmd "go test ./pkg")))))
+
+;;; Boundary Cases
+
+(ert-deftest test-dev-fkeys-f6-current-file-tests-impl-go-source-at-root ()
+  "Boundary: a Go source file at project root runs `go test ./'."
+  (let (seen-cmd)
+    (cl-letf (((symbol-function 'compile)
+               (lambda (cmd) (setq seen-cmd cmd))))
+      (cj/--f6-current-file-tests-impl
+       "/home/u/proj/main.go"
+       "/home/u/proj/")
+      (should (string= seen-cmd "go test ./")))))
+
+(ert-deftest test-dev-fkeys-f6-current-file-tests-impl-elisp-double-dash-test ()
+  "Boundary: a per-helper elisp test file runs `make test-file FILE=...' so
+just that file's tests run, not the whole module's prefix."
+  (let (seen-cmd)
+    (cl-letf (((symbol-function 'compile)
+               (lambda (cmd) (setq seen-cmd cmd))))
+      (cj/--f6-current-file-tests-impl
+       "/home/u/proj/tests/test-foo--bar.el"
+       "/home/u/proj/")
+      (should (string= seen-cmd "make test-file FILE=tests/test-foo--bar.el")))))
+
+;;; Error Cases
+
+(ert-deftest test-dev-fkeys-f6-current-file-tests-impl-nil-file-errors ()
+  "Error: nil FILE signals a user-error."
+  (cl-letf (((symbol-function 'compile) (lambda (_cmd) nil)))
+    (should-error (cj/--f6-current-file-tests-impl nil "/home/u/proj/")
+                  :type 'user-error)))
+
+(ert-deftest test-dev-fkeys-f6-current-file-tests-impl-nil-root-errors ()
+  "Error: nil PROJECT-ROOT signals a user-error."
+  (cl-letf (((symbol-function 'compile) (lambda (_cmd) nil)))
+    (should-error (cj/--f6-current-file-tests-impl
+                   "/home/u/proj/modules/foo.el" nil)
+                  :type 'user-error)))
+
+(ert-deftest test-dev-fkeys-f6-current-file-tests-impl-unsupported-language-errors ()
+  "Error: a file with no language-specific runner signals a user-error
+naming the language."
+  (cl-letf (((symbol-function 'compile) (lambda (_cmd) nil)))
+    (should-error (cj/--f6-current-file-tests-impl
+                   "/home/u/proj/src/foo.test.ts" "/home/u/proj/")
+                  :type 'user-error)))
+
+(ert-deftest test-dev-fkeys-f6-current-file-tests-impl-unknown-language-errors ()
+  "Error: an unknown extension signals a user-error rather than running
+something the user didn't ask for."
+  (cl-letf (((symbol-function 'compile) (lambda (_cmd) nil)))
+    (should-error (cj/--f6-current-file-tests-impl
+                   "/home/u/proj/Makefile" "/home/u/proj/")
+                  :type 'user-error)))
+
+(provide 'test-dev-fkeys--f6-current-file-tests-impl)
+;;; test-dev-fkeys--f6-current-file-tests-impl.el ends here