"""Tests for patch rendering (SHARD-WP-0008 T3)."""

from shard_wiki.coordination import Overlay, Patch, render_patch
from shard_wiki.model import Identity


def _overlay(body: str) -> Overlay:
    return Overlay("ov1", Identity("shardA", "Home"), base_rev="r1", body=body)


def test_patch_shows_the_change():
    patch = render_patch(_overlay("line one\nline TWO\n"), "line one\nline two\n")
    assert isinstance(patch, Patch)
    assert not patch.is_empty
    assert "-line two" in patch.diff
    assert "+line TWO" in patch.diff
    assert patch.target == Identity("shardA", "Home")


def test_empty_patch_when_unchanged():
    patch = render_patch(_overlay("same\n"), "same\n")
    assert patch.is_empty
    assert patch.diff == ""


def test_patch_labels_name_the_target():
    patch = render_patch(_overlay("new\n"), "old\n")
    assert "a/shardA:Home" in patch.diff
    assert "b/shardA:Home" in patch.diff