fix(filters): honour whole_word

The whole_word field was stored and returned by the API, but the regex
always used word boundaries. As in Mastodon, a filter with whole_word
false now also matches inside words.

changelog.d/filter-whole-word.fix

@@ -0,0 +1 @@
+Filters with whole_word set to false now also match inside words

lib/pleroma/filter.ex

@@ -212,7 +212,7 @@ defmodule Pleroma.Filter do
 
     phrases =
       filters
-      |> Enum.map(&phrase_regex(&1.phrase, boundary))
+      |> Enum.map(&phrase_regex(&1, boundary))
       |> Enum.join("|")
 
     case format do
@@ -223,9 +223,12 @@ defmodule Pleroma.Filter do
 
   def compose_regex(_, _), do: nil
 
-  # Phrases are literal text. Like Mastodon, only add a word boundary
-  # where the phrase starts or ends with a word character.
-  defp phrase_regex(phrase, boundary) do
+  # Phrases are literal text. Like Mastodon, whole-word filters only get a
+  # word boundary where the phrase starts or ends with a word character.
+  defp phrase_regex(%__MODULE__{phrase: phrase, whole_word: false}, _boundary),
+    do: Regex.escape(phrase)
+
+  defp phrase_regex(%__MODULE__{phrase: phrase}, boundary) do
     prefix = if String.match?(phrase, ~r/^\w/u), do: boundary, else: ""
     suffix = if String.match?(phrase, ~r/\w$/u), do: boundary, else: ""
 

test/pleroma/filter_test.exs

@@ -233,6 +233,17 @@ defmodule Pleroma.FilterTest do
       end
     end
 
+    test "matches inside words when whole_word is false" do
+      filters = [%Filter{phrase: "cat", whole_word: false}, %Filter{phrase: "dog"}]
+      pg = Filter.compose_regex(filters)
+      re = Filter.compose_regex(filters, :re)
+
+      for {text, expected} <- [{"a catalog", true}, {"a hotdog", false}, {"a dog", true}] do
+        assert pg_match?(pg, text) == expected
+        assert Regex.match?(re, text) == expected
+      end
+    end
+
     test "keeps word boundaries for every phrase in Elixir" do
       regex = Filter.compose_regex(filters(["cat", "dog"]), :re)