feat: add code action for the ParenthesesOnZeroArityDefs check (#76)

* feat: Add code action for the ParenthesesOnZeroArityDefs check

---------

Co-authored-by: Mitchell Hanberg <[email protected]>

lib/credo_language_server/check.ex

@@ -3,6 +3,11 @@ defmodule CredoLanguageServer.Check do
   Data structure for Credo Checks.
   """
 
+  alias Credo.Check.Readability.{
+    ModuleDoc,
+    ParenthesesOnZeroArityDefs
+  }
+
   @doc """
   Data structure that holds information related to an instance of a check found by Credo.
   """
@@ -16,39 +21,45 @@ defmodule CredoLanguageServer.Check do
   defimpl CredoLanguageServer.CodeActionable do
     alias CredoLanguageServer.CodeAction
 
-    def fetch(%{
-          check: Credo.Check.Readability.ModuleDoc = check,
-          diagnostic: diagnostic,
-          uri: uri,
-          document: document
-        }) do
+    def fetch(%{check: ModuleDoc} = ca) do
       [
         CodeAction.DisableCheck.new(
-          uri: uri,
-          diagnostic: diagnostic,
-          text: document,
-          check: Macro.to_string(check)
+          uri: ca.uri,
+          diagnostic: ca.diagnostic,
+          text: ca.document,
+          check: Macro.to_string(ca.check)
         ),
         CodeAction.ModuleDocFalse.new(
-          uri: uri,
-          diagnostic: diagnostic,
-          text: document
+          uri: ca.uri,
+          diagnostic: ca.diagnostic,
+          text: ca.document
+        )
+      ]
+    end
+
+    def fetch(%{check: ParenthesesOnZeroArityDefs} = ca) do
+      [
+        CodeAction.DisableCheck.new(
+          uri: ca.uri,
+          diagnostic: ca.diagnostic,
+          text: ca.document,
+          check: Macro.to_string(ca.check)
+        ),
+        CodeAction.ParenthesesOnZeroArityDefs.new(
+          uri: ca.uri,
+          diagnostic: ca.diagnostic,
+          text: ca.document
         )
       ]
     end
 
-    def fetch(%{
-          check: check,
-          diagnostic: diagnostic,
-          uri: uri,
-          document: document
-        }) do
+    def fetch(ca) do
       [
         CodeAction.DisableCheck.new(
-          uri: uri,
-          diagnostic: diagnostic,
-          text: document,
-          check: Macro.to_string(check)
+          uri: ca.uri,
+          diagnostic: ca.diagnostic,
+          text: ca.document,
+          check: Macro.to_string(ca.check)
         )
       ]
     end

lib/credo_language_server/code_action/parentheses_on_zero_arity_defs.ex

@@ -0,0 +1,56 @@
+defmodule CredoLanguageServer.CodeAction.ParenthesesOnZeroArityDefs do
+  @moduledoc false
+
+  alias GenLSP.Structures.{
+    CodeAction,
+    Diagnostic,
+    Position,
+    Range,
+    TextEdit,
+    WorkspaceEdit
+  }
+
+  require Logger
+
+  defp opts do
+    Schematic.map(%{
+      # TODO: schematic needs a way to define a struct
+      diagnostic: Schematic.any(),
+      uri: Schematic.str(),
+      text: Schematic.list(Schematic.str())
+    })
+  end
+
+  def new(opts) do
+    {:ok,
+     %{
+       diagnostic: %Diagnostic{range: %{start: start}} = diagnostic,
+       uri: uri,
+       text: text
+     }} = Schematic.unify(opts(), Map.new(opts))
+
+    function_definition = Enum.at(text, start.line)
+    new_text = String.replace(function_definition, "()", "", global: false)
+
+    %CodeAction{
+      title: "Remove parentheses",
+      diagnostics: [diagnostic],
+      edit: %WorkspaceEdit{
+        changes: %{
+          uri => [
+            %TextEdit{
+              new_text: new_text,
+              range: %Range{
+                start: start,
+                end: %Position{
+                  start
+                  | character: String.length(function_definition)
+                }
+              }
+            }
+          ]
+        }
+      }
+    }
+  end
+end

test/credo_language_server/code_action/parentheses_on_zero_arity_defs_test.exs

@@ -0,0 +1,104 @@
+defmodule CredoLanguageServer.CodeAction.ParenthesesOnZeroArityDefsTest do
+  use ExUnit.Case, async: true
+
+  alias CredoLanguageServer.CodeAction.ParenthesesOnZeroArityDefs
+
+  alias GenLSP.Structures.{
+    CodeAction,
+    CodeDescription,
+    Diagnostic,
+    Position,
+    Range,
+    TextEdit,
+    WorkspaceEdit
+  }
+
+  describe "new" do
+    test "provides a code action that removes unnecessary parentheses" do
+      diagnostic = %Diagnostic{
+        data: %{
+          "check" =>
+            "Elixir.Credo.Check.Readability.ParenthesesOnZeroArityDefs",
+          "file" => "foo.ex"
+        },
+        related_information: nil,
+        tags: nil,
+        message:
+          "Do not use parentheses when defining a function which has no arguments.",
+        source: "credo",
+        code_description: %CodeDescription{
+          href:
+            "https://hexdocs.pm/credo/Credo.Check.Readability.ParenthesesOnZeroArityDefs.html"
+        },
+        code: "Credo.Check.Readability.ParenthesesOnZeroArityDefs",
+        severity: 3,
+        range: %Range{
+          start: %Position{character: 0, line: 1},
+          end: %Position{character: 1, line: 1}
+        }
+      }
+
+      text = [
+        "defmodule Test do",
+        "  def foo() do",
+        "    :bar",
+        "  end",
+        "end",
+        ""
+      ]
+
+      assert %CodeAction{
+               title: "Remove parentheses",
+               diagnostics: [^diagnostic],
+               edit: %WorkspaceEdit{
+                 changes: %{
+                   "uri" => [
+                     %TextEdit{
+                       new_text: "  def foo do",
+                       range: %Range{
+                         start: %Position{character: 0, line: 1},
+                         end: %Position{character: 14, line: 1}
+                       }
+                     }
+                   ]
+                 }
+               }
+             } =
+               ParenthesesOnZeroArityDefs.new(%{
+                 diagnostic: diagnostic,
+                 text: text,
+                 uri: "uri"
+               })
+
+      text = [
+        "defmodule Test do",
+        "  def foo(), do: bar()",
+        "end",
+        ""
+      ]
+
+      assert %CodeAction{
+               title: "Remove parentheses",
+               diagnostics: [^diagnostic],
+               edit: %WorkspaceEdit{
+                 changes: %{
+                   "uri" => [
+                     %TextEdit{
+                       new_text: "  def foo, do: bar()",
+                       range: %Range{
+                         start: %Position{character: 0, line: 1},
+                         end: %Position{character: 22, line: 1}
+                       }
+                     }
+                   ]
+                 }
+               }
+             } =
+               ParenthesesOnZeroArityDefs.new(%{
+                 diagnostic: diagnostic,
+                 text: text,
+                 uri: "uri"
+               })
+    end
+  end
+end