Handle edge cases

lib/ex_factor/remover.ex

@@ -18,6 +18,7 @@ defmodule ExFactor.Remover do
     arity = Keyword.fetch!(opts, :arity)
     source_path = Keyword.get(opts, :source_path, path(source_module))
     dry_run = Keyword.get(opts, :dry_run, false)
+    guard_mismatch!(source_module, source_path)
 
     {_ast, block_contents} = Parser.all_functions(source_path)
     fns_to_remove = Enum.filter(block_contents, &(&1.name == source_function))
@@ -36,7 +37,22 @@ defmodule ExFactor.Remover do
       |> List.insert_at(function.start_line - 1, comment(source_function, arity, function.defn))
     end)
     |> Enum.join("\n")
-    |> then(fn str -> write_file(source_path, str, source_module, dry_run) end)
+    |> then(fn str -> write_file(fns_to_remove, source_path, str, source_module, dry_run) end)
+  end
+
+  defp guard_mismatch!(module_string, source_path) when is_binary(module_string) do
+    source_path
+    |> File.read!()
+    |> String.match?(~r/#{module_string}/)
+    |> unless do
+      raise ArgumentError,
+            "Module name: #{module_string} not detected in source path: '#{source_path}'"
+    end
+  end
+
+  defp guard_mismatch!(source_module, source_path) do
+    module_string = Module.split(source_module) |> Enum.join(".")
+    guard_mismatch!(module_string, source_path)
   end
 
   defp comment(name, arity, "@spec") do
@@ -56,7 +72,7 @@ defmodule ExFactor.Remover do
     """
   end
 
-  defp write_file(path, contents, source_module, true) do
+  defp write_file(_, path, contents, source_module, true) do
     %ExFactor{
       module: source_module,
       path: path,
@@ -66,7 +82,17 @@ defmodule ExFactor.Remover do
     }
   end
 
-  defp write_file(path, contents, source_module, _) do
+  defp write_file([], path, contents, source_module, _) do
+    %ExFactor{
+      module: source_module,
+      path: path,
+      state: [:unchanged],
+      message: "function not matched",
+      file_contents: contents
+    }
+  end
+
+  defp write_file(_, path, contents, source_module, _) do
     File.write(path, contents, [:write])
 
     %ExFactor{

test/ex_factor/extractor_test.exs

@@ -297,6 +297,7 @@ defmodule ExFactor.ExtractorTest do
     end
 
     @tag :skip
+    # Need to implemnt this functionality
     test "extract references to the function in the source module" do
       content = """
       defmodule ExFactorSampleModule do

test/ex_factor/remover_test.exs

@@ -169,9 +169,85 @@ defmodule ExFactor.RemoverTest do
     end
 
     test "handles no functions found to remove, messages correctly" do
+      content = """
+      defmodule ExFactorSampleModule do
+        @somedoc "This is somedoc"
+        # a comment and no aliases
+        _docp = "here's an arbitrary module underscore"
+        def pub1(arg1) do
+          :ok
+        end
+      end
+      """
+
+      File.write("test/tmp/source_module.ex", content)
+
+      opts = [
+        source_module: ExFactorSampleModule,
+        source_path: "test/tmp/source_module.ex",
+        source_function: :pub2,
+        arity: 1
+      ]
+
+      struct = Remover.remove(opts)
+
+      assert struct.state == [:unchanged]
+      assert struct.message == "function not matched"
     end
 
     test "handles no modules found to remove, messages correctly" do
+      content = """
+      defmodule ExFactorSampleModule do
+        @somedoc "This is somedoc"
+        # a comment and no aliases
+        _docp = "here's an arbitrary module underscore"
+        def pub1(arg1) do
+          :ok
+        end
+      end
+      """
+
+      File.write("test/tmp/source_module.ex", content)
+
+      opts = [
+        source_module: ExFactorSampleModule,
+        source_function: :pub1,
+        arity: 1
+      ]
+
+      assert_raise File.Error,
+                   "could not read file \"lib/ex_factor_sample_module.ex\": no such file or directory",
+                   fn ->
+                     Remover.remove(opts)
+                   end
+    end
+
+    test "when the module name doesn't match the module in the path" do
+      content = """
+      defmodule ExFactorUnmatchedModule do
+        @somedoc "This is somedoc"
+        # a comment and no aliases
+        _docp = "here's an arbitrary module underscore"
+        def pub1(arg1) do
+          :ok
+        end
+      end
+      """
+
+      File.write("test/tmp/source_module.ex", content)
+
+      opts = [
+        source_module: ExFactorSampleModule,
+        source_path: "test/tmp/source_module.ex",
+        source_function: :pub1,
+        arity: 1
+      ]
+
+      assert_raise ArgumentError,
+                   "Module name: ExFactorSampleModule not detected in source path: 'test/tmp/source_module.ex'",
+                   fn ->
+                     Remover.remove(opts)
+                   end
     end
   end
 end