Consolidate completely stateless tests into doctests

Removing dupes

lib/music_brainz/release_search_result.ex

@@ -16,6 +16,44 @@ defmodule MusicBrainz.ReleaseSearchResult do
     }
   end
 
+  @doc """
+  Returns the physical format of a release based on its media.
+
+  Returns `:multi` when a release contains different format types.
+
+  ## Examples
+
+      iex> MusicBrainz.ReleaseSearchResult.format(%MusicBrainz.ReleaseSearchResult{
+      ...>   id: "1", title: "T", release_group: nil, artists: "A", date: "2000", barcode: "0",
+      ...>   media: [%{format: "CD", disc_count: 1, track_count: 11}]
+      ...> })
+      :cd
+
+      iex> MusicBrainz.ReleaseSearchResult.format(%MusicBrainz.ReleaseSearchResult{
+      ...>   id: "1", title: "T", release_group: nil, artists: "A", date: "2000", barcode: "0",
+      ...>   media: [%{format: "12\\" Vinyl", disc_count: 0, track_count: 8}]
+      ...> })
+      :vinyl
+
+      iex> MusicBrainz.ReleaseSearchResult.format(%MusicBrainz.ReleaseSearchResult{
+      ...>   id: "1", title: "T", release_group: nil, artists: "A", date: "2000", barcode: "0",
+      ...>   media: [
+      ...>     %{format: "CD", disc_count: 1, track_count: 10},
+      ...>     %{format: "CD", disc_count: 1, track_count: 9}
+      ...>   ]
+      ...> })
+      :cd
+
+      iex> MusicBrainz.ReleaseSearchResult.format(%MusicBrainz.ReleaseSearchResult{
+      ...>   id: "1", title: "T", release_group: nil, artists: "A", date: "2000", barcode: "0",
+      ...>   media: [
+      ...>     %{format: "CD", disc_count: 0, track_count: 11},
+      ...>     %{format: "DVD-Video", disc_count: 0, track_count: 22}
+      ...>   ]
+      ...> })
+      :multi
+
+  """
   def format(release_search_result) do
     sorted_frequencies =
       release_search_result.media

lib/music_library/country.ex

@@ -276,12 +276,45 @@ defmodule MusicLibrary.Country do
       iex> MusicLibrary.Country.to_emoji("US")
       "🇺🇸"
 
+      iex> MusicLibrary.Country.to_emoji("PL")
+      "🇵🇱"
+
+      iex> MusicLibrary.Country.to_emoji("GB")
+      "🇬🇧"
+
+      iex> MusicLibrary.Country.to_emoji("us")
+      "🇺🇸"
+
+      iex> MusicLibrary.Country.to_emoji("pl")
+      "🇵🇱"
+
       iex> MusicLibrary.Country.to_emoji("GB-SCT")
       "🏴󠁧󠁢󠁳󠁣󠁴󠁿"
 
+      iex> MusicLibrary.Country.to_emoji("GB-WLS")
+      "🏴󠁧󠁢󠁷󠁬󠁳󠁿"
+
+      iex> MusicLibrary.Country.to_emoji("GB-ENG")
+      "🏴󠁧󠁢󠁥󠁮󠁧󠁿"
+
+      iex> MusicLibrary.Country.to_emoji("GB-CYM") == MusicLibrary.Country.to_emoji("GB-WLS")
+      true
+
       iex> MusicLibrary.Country.to_emoji("USA")
       "🇺🇸"
 
+      iex> MusicLibrary.Country.to_emoji("GBR")
+      "🇬🇧"
+
+      iex> MusicLibrary.Country.to_emoji("POL")
+      "🇵🇱"
+
+      iex> MusicLibrary.Country.to_emoji("en-US")
+      "🇺🇸"
+
+      iex> MusicLibrary.Country.to_emoji("pl-PL")
+      "🇵🇱"
+
   """
   @spec to_emoji(String.t()) :: String.t()
   def to_emoji(code) when is_binary(code) do

lib/music_library_web/duration.ex

@@ -1,4 +1,26 @@
 defmodule MusicLibraryWeb.Duration do
+  @moduledoc """
+  Formats durations from milliseconds to human-readable strings.
+  """
+
+  @doc """
+  Formats a duration in milliseconds as a human-readable string.
+
+  ## Examples
+
+      iex> MusicLibraryWeb.Duration.format_duration(30_000)
+      "0:30"
+
+      iex> MusicLibraryWeb.Duration.format_duration(90_000)
+      "1:30"
+
+      iex> MusicLibraryWeb.Duration.format_duration(3_723_000)
+      "1:02:03"
+
+      iex> MusicLibraryWeb.Duration.format_duration(0)
+      "0:00"
+
+  """
   def format_duration(milliseconds) do
     milliseconds
     |> System.convert_time_unit(:millisecond, :second)