feat(highlight): vim highlight fallback

spec/highlight_spec.lua

@@ -31,20 +31,25 @@ describe('highlight', function()
 
     local function default_opts(overrides)
       local opts = {
-        max_lines = 500,
         hide_prefix = false,
+        treesitter = {
+          enabled = true,
+          max_lines = 500,
+        },
+        vim = {
+          enabled = false,
+          max_lines = 200,
+        },
         highlights = {
-          treesitter = true,
           background = false,
           gutter = false,
-          vim = false,
         },
       }
       if overrides then
         for k, v in pairs(overrides) do
-          if k == 'highlights' then
-            for hk, hv in pairs(v) do
-              opts.highlights[hk] = hv
+          if type(v) == 'table' and type(opts[k]) == 'table' then
+            for sk, sv in pairs(v) do
+              opts[k][sk] = sv
             end
           else
             opts[k] = v
@@ -478,7 +483,7 @@ describe('highlight', function()
         bufnr,
         ns,
         hunk,
-        default_opts({ highlights = { treesitter = false, background = true } })
+        default_opts({ treesitter = { enabled = false }, highlights = { background = true } })
       )
 
       local extmarks = get_extmarks(bufnr)
@@ -511,7 +516,7 @@ describe('highlight', function()
         bufnr,
         ns,
         hunk,
-        default_opts({ highlights = { treesitter = false, background = true } })
+        default_opts({ treesitter = { enabled = false }, highlights = { background = true } })
       )
 
       local extmarks = get_extmarks(bufnr)

spec/parser_spec.lua

@@ -48,6 +48,7 @@ describe('parser', function()
 
       assert.are.equal(1, #hunks)
       assert.are.equal('lua/test.lua', hunks[1].filename)
+      assert.are.equal('lua', hunks[1].ft)
       assert.are.equal('lua', hunks[1].lang)
       assert.are.equal(3, hunks[1].start_line)
       assert.are.equal(3, #hunks[1].lines)
@@ -156,6 +157,25 @@ describe('parser', function()
       delete_buffer(bufnr)
     end)
 
+    it('emits hunk with ft when no ts parser available', function()
+      local bufnr = create_buffer({
+        'M test.xyz_no_parser',
+        '@@ -1,1 +1,2 @@',
+        ' some content',
+        '+more content',
+      })
+
+      vim.filetype.add({ extension = { xyz_no_parser = 'xyz_no_parser_ft' } })
+
+      local hunks = parser.parse_buffer(bufnr)
+
+      assert.are.equal(1, #hunks)
+      assert.are.equal('xyz_no_parser_ft', hunks[1].ft)
+      assert.is_nil(hunks[1].lang)
+      assert.are.equal(2, #hunks[1].lines)
+      delete_buffer(bufnr)
+    end)
+
     it('stops hunk at next file header', function()
       local bufnr = create_buffer({
         'M test.lua',