import pytest
from src.synthesis_formatter import format_takes_diff

def test_format_takes_diff_empty():
 assert format_takes_diff({}) == ""

def test_format_takes_diff_single_take():
 takes = {
  "take1": [
   {"role": "user", "content": "hello"},
   {"role": "assistant", "content": "hi"}
  ]
 }
 expected = "=== Shared History ===\nuser: hello\nassistant: hi\n\n=== Variations ===\n"
 assert format_takes_diff(takes) == expected

def test_format_takes_diff_common_prefix():
 takes = {
  "take1": [
   {"role": "user", "content": "hello"},
   {"role": "assistant", "content": "hi"},
   {"role": "user", "content": "how are you?"},
   {"role": "assistant", "content": "I am fine."}
  ],
  "take2": [
   {"role": "user", "content": "hello"},
   {"role": "assistant", "content": "hi"},
   {"role": "user", "content": "what is the time?"},
   {"role": "assistant", "content": "It is noon."}
  ]
 }
 expected = (
  "=== Shared History ===\n"
  "user: hello\n"
  "assistant: hi\n\n"
  "=== Variations ===\n"
  "[take1]\n"
  "user: how are you?\n"
  "assistant: I am fine.\n\n"
  "[take2]\n"
  "user: what is the time?\n"
  "assistant: It is noon.\n"
 )
 assert format_takes_diff(takes) == expected

def test_format_takes_diff_no_common_prefix():
 takes = {
  "take1": [{"role": "user", "content": "a"}],
  "take2": [{"role": "user", "content": "b"}]
 }
 expected = (
  "=== Shared History ===\n\n"
  "=== Variations ===\n"
  "[take1]\n"
  "user: a\n\n"
  "[take2]\n"
  "user: b\n"
 )
 assert format_takes_diff(takes) == expected