feat(diagnostics): accept functions as symbols

lua/lualine/components/diagnostics/init.lua

@@ -50,6 +50,14 @@ function M:init(options)
   end
 end
 
+local function render_diagnostic(symbol_or_function, count)
+  if type(symbol_or_function) == 'function' then
+    return symbol_or_function(count)
+  else
+    return symbol_or_function .. count
+  end
+end
+
 function M:update_status()
   local bufnr = vim.api.nvim_get_current_buf()
   local diagnostics_count
@@ -95,13 +103,16 @@ function M:update_status()
       if diagnostics_count[section] ~= nil and (always_visible or diagnostics_count[section] > 0) then
         padding = previous_section and (bgs[previous_section] ~= bgs[section]) and ' ' or ''
         previous_section = section
-        table.insert(result, colors[section] .. padding .. self.symbols[section] .. diagnostics_count[section])
+        table.insert(
+          result,
+          colors[section] .. padding .. render_diagnostic(self.symbols[section], diagnostics_count[section])
+        )
       end
     end
   else
     for _, section in ipairs(self.options.sections) do
       if diagnostics_count[section] ~= nil and (always_visible or diagnostics_count[section] > 0) then
-        table.insert(result, self.symbols[section] .. diagnostics_count[section])
+        table.insert(result, render_diagnostic(self.symbols[section], diagnostics_count[section]))
       end
     end
   end

tests/spec/component_spec.lua

@@ -820,3 +820,50 @@ describe('Branch component', function()
     assert_component('branch', opts, rev)
   end)
 end)
+
+describe('Diagnostics component', function()
+  local assert_comp_ins = helpers.assert_component_instance
+  local sources = {
+    function()
+      return { error = 1, warn = 2, info = 3, hint = 4 }
+    end,
+  }
+
+  it('renders the diagnostics with static symbols', function()
+    local opts = build_component_opts {
+      sources = sources,
+      colored = false,
+      symbols = {
+        error = 'E',
+        warn = 'W',
+        info = 'I',
+        hint = 'H',
+      },
+    }
+    local dc = helpers.init_component('diagnostics', opts)
+    assert_comp_ins(dc, ' E1 W2 I3 H4 ')
+  end)
+
+  it('renders the diagnostics with dynamic symbols', function()
+    local opts = build_component_opts {
+      sources = sources,
+      colored = false,
+      symbols = {
+        error = function(c)
+          return c .. ' foo'
+        end,
+        warn = function(c)
+          return c .. ' bar'
+        end,
+        info = function(c)
+          return c .. ' baz'
+        end,
+        hint = function(c)
+          return c .. ' qux'
+        end,
+      },
+    }
+    local dc = helpers.init_component('diagnostics', opts)
+    assert_comp_ins(dc, ' 1 foo 2 bar 3 baz 4 qux ')
+  end)
+end)