test: Make all tests work

Makefile

@@ -1,5 +1,5 @@
 .PHONY: all clean test
 
 test:
-	nvim --headless --clean -u tests/init-minimal.vim -c "PlenaryBustedFile tests/minimal.lua"
-	nvim --headless --clean -u tests/init-treesitter.vim -c "PlenaryBustedFile tests/treesitter.lua"
+	nvim --headless --clean -u tests/init.vim -c "PlenaryBustedFile tests/minimal.lua"
+	nvim --headless --clean -u tests/init.vim -c "PlenaryBustedFile tests/treesitter.lua"

tests/common.lua

@@ -1,5 +1,8 @@
 local M = {}
 
+vim.o.hidden = true
+vim.o.swapfile = false
+
 local wrapping = require("wrapping")
 
 M.set_lines = function(lines)

tests/init-minimal.vim → tests/init.vim

@@ -1,7 +1,4 @@
-set hidden
-set noswapfile
-
 set rtp+=~/.local/share/nvim/site/pack/vendor/start/plenary.nvim
 set rtp+=../plenary.nvim
-set rtp+=.
+
 runtime! plugin/plenary.vim

tests/treesitter.lua

@@ -1,3 +1,27 @@
+vim.opt.runtimepath:prepend(
+    "~/.local/share/nvim/site/pack/vendor/start/nvim-treesitter"
+)
+vim.opt.runtimepath:prepend("../nvim-treesitter")
+
+vim.cmd("runtime! plugin/nvim-treesitter.lua")
+
+local install_parser_if_needed = function(filetype)
+    if vim.tbl_contains(vim.tbl_keys(vim.fn.environ()), "GITHUB_WORKFLOW") then
+        print("Running in GitHub; installing parser " .. filetype .. "...")
+        vim.cmd("TSInstallSync! " .. filetype)
+    else
+        vim.cmd("new")
+        vim.cmd("only")
+        local ok, _ = pcall(vim.treesitter.get_parser, 0, filetype, {})
+        if not ok then
+            print("Cannot load parser for " .. filetype .. ", installing...")
+            vim.cmd("TSInstallSync! " .. filetype)
+        end
+    end
+end
+
+install_parser_if_needed("markdown")
+
 local common = require("tests.common")
 local wrapping = require("wrapping")