feat: issue #32 markdown editor for TUI

test/bds/tui_test.exs

@@ -38,14 +38,18 @@ defmodule BDS.TUITest do
     state
   end
 
-  defp screen_text(state, width \\ 100, height \\ 32) do
+  defp screen_cells(state, width \\ 100, height \\ 32) do
     session = CellSession.new(width, height)
     frame = %ExRatatui.Frame{width: width, height: height}
     :ok = CellSession.draw(session, BDS.TUI.render(state, frame))
     snapshot = CellSession.take_cells(session)
     :ok = CellSession.close(session)
-
     snapshot.cells
+  end
+
+  defp screen_text(state, width \\ 100, height \\ 32) do
+    state
+    |> screen_cells(width, height)
     |> Enum.group_by(& &1.row)
     |> Enum.sort_by(fn {row, _} -> row end)
     |> Enum.map_join("\n", fn {_row, cells} ->
@@ -53,6 +57,22 @@ defmodule BDS.TUITest do
     end)
   end
 
+  # The cell where `text` starts on screen (used to assert per-cell styles).
+  defp cell_at_text(cells, text) do
+    {_row, row_cells} =
+      cells
+      |> Enum.group_by(& &1.row)
+      |> Enum.find(fn {_row, row_cells} ->
+        row_cells |> Enum.sort_by(& &1.col) |> Enum.map_join("", & &1.symbol) |> String.contains?(text)
+      end)
+
+    sorted = Enum.sort_by(row_cells, & &1.col)
+    joined = Enum.map_join(sorted, & &1.symbol)
+    {byte_offset, _len} = :binary.match(joined, text)
+    char_offset = joined |> binary_part(0, byte_offset) |> String.length()
+    Enum.at(sorted, char_offset)
+  end
+
   defp key(code, modifiers), do: %Key{code: code, kind: "press", modifiers: modifiers}
 
   defp press(state, code, modifiers \\ []) do
@@ -68,7 +88,7 @@ defmodule BDS.TUITest do
     assert text =~ "Hello TUI"
   end
 
-  test "opening a post lands in the markdown preview, not the editor", %{post: post} do
+  test "opening a post lands in the editor with the raw source", %{post: post} do
     {:ok, _} =
       BDS.Posts.update_post(post.id, %{content: "# Big Heading\n\nsome **bold** words"})
 
@@ -76,19 +96,66 @@ defmodule BDS.TUITest do
 
     assert state.focus == :editor
     assert state.editor.post.id == post.id
+    refute state.editor.preview?
+
+    # The editor shows the raw markdown source.
+    assert screen_text(state) =~ "**bold**"
+
+    # ctrl+e flips to the rendered markdown preview: inline markers are
+    # consumed by the styling.
+    state = press(state, "e", ["ctrl"])
     assert state.editor.preview?
 
     text = screen_text(state)
     assert text =~ "Big Heading"
-    # Rendered markdown: inline markers are consumed by the styling
-    # (headings keep their # but get styled, invisible in a text dump).
     assert text =~ "some bold words"
     refute text =~ "**bold**"
 
-    # ctrl+e drops into the editing textarea with the raw source.
+    # and back to the editor.
     state = press(state, "e", ["ctrl"])
     refute state.editor.preview?
-    assert ExRatatui.textarea_get_value(state.editor.textarea) =~ "**bold**"
+    assert screen_text(state) =~ "**bold**"
+  end
+
+  test "the editor word-wraps long lines", %{post: post} do
+    long_line = String.duplicate("lorem ipsum dolor sit amet ", 8) <> "FINALWORD"
+    {:ok, _} = BDS.Posts.update_post(post.id, %{content: long_line})
+
+    state = mount!() |> press("enter")
+    refute state.editor.preview?
+
+    # The tail of a long line wraps onto visible rows without any
+    # horizontal scrolling.
+    assert screen_text(state, 80, 32) =~ "FINALWORD"
+  end
+
+  test "the cursor cell stays visible when the cursor sits below the viewport", %{post: post} do
+    content = Enum.map_join(1..30, "\n", &"line #{&1}")
+    {:ok, _} = BDS.Posts.update_post(post.id, %{content: content})
+
+    state = mount!() |> press("enter")
+
+    # The cursor opens at the end of the buffer — source row 29 of 30.
+    assert ExRatatui.textarea_cursor(state.editor.textarea) == {29, 7}
+
+    cells = screen_cells(state)
+    # The cursor cell is the single space carrying the cursor background
+    # inside the editor area (the sidebar selection also uses a cyan bg).
+    assert Enum.any?(cells, &(&1.bg == :cyan and &1.symbol == " " and &1.col >= 34))
+  end
+
+  test "the cursor line has a distinct background from the other lines", %{post: post} do
+    {:ok, _} = BDS.Posts.update_post(post.id, %{content: "first\nsecond\nthird"})
+
+    state = mount!() |> press("enter")
+
+    # Move the cursor from the end of the buffer onto the first line.
+    state = state |> press("up") |> press("up")
+    assert ExRatatui.textarea_cursor(state.editor.textarea) == {0, 5}
+
+    cells = screen_cells(state)
+    assert cell_at_text(cells, "first").bg == :dark_gray
+    refute cell_at_text(cells, "second").bg == :dark_gray
   end
 
   test "ctrl+s persists textarea edits", %{post: post} do
@@ -126,26 +193,17 @@ defmodule BDS.TUITest do
     assert state.focus == :sidebar
   end
 
-  test "the preview word-wraps and ctrl+e toggles back and forth", %{post: post} do
+  test "the preview word-wraps long lines", %{post: post} do
     long_line = String.duplicate("lorem ipsum dolor sit amet ", 8) <> "FINALWORD"
     {:ok, _} = BDS.Posts.update_post(post.id, %{content: long_line})
 
-    state = mount!() |> press("enter")
+    state = mount!() |> press("enter") |> press("e", ["ctrl"])
     assert state.editor.preview?
-
-    # The textarea cannot soft-wrap, so the tail of a long line is off-screen
-    # there; the preview renders through the Markdown widget, which wraps.
     assert screen_text(state, 80, 32) =~ "FINALWORD"
-
-    state = press(state, "e", ["ctrl"])
-    refute state.editor.preview?
-
-    state = press(state, "e", ["ctrl"])
-    assert state.editor.preview?
   end
 
   test "keys in preview mode do not edit the content" do
-    state = mount!() |> press("enter")
+    state = mount!() |> press("enter") |> press("e", ["ctrl"])
     assert state.editor.preview?
     before = ExRatatui.textarea_get_value(state.editor.textarea)