tests: Add style test

Author: JanEbbing

tests/test_rephrase_text.py

@@ -2,15 +2,33 @@
 # Use of this source code is governed by an MIT
 # license that can be found in the LICENSE file.
 
-from .conftest import example_text
+from .conftest import example_text, needs_real_server
+from deepl.api_data import WriteResult, WritingStyle
 
 
 def test_single_text(deepl_client):
     result = deepl_client.rephrase_text(
         example_text["EN"], target_lang="EN-GB"
     )
-    assert result.detected_source_language.upper() == "EN"
-    epsilon = 0.2
-    n_original = len(example_text["EN"])
+    _check_sanity_of_improvements(example_text["EN"], result)
+
+
+@needs_real_server
+def test_business_style(deepl_client):
+    input_text = "As Gregor Samsa awoke one morning from uneasy dreams he found himself transformed in his bed into a gigantic insect."  # noqa
+    result = deepl_client.rephrase_text(
+        input_text, target_lang="EN-US", style=WritingStyle.BUSINESS.value
+    )
+    _check_sanity_of_improvements(input_text, result)
+
+
+def _check_sanity_of_improvements(
+    input_text: str,
+    result: WriteResult,
+    expected_lang_uppercase="EN",
+    epsilon=0.2,
+):
+    assert result.detected_source_language.upper() == expected_lang_uppercase
     n_improved = len(result.text)
+    n_original = len(input_text)
     assert 1 / (1.0 + epsilon) <= n_improved / n_original <= (1.0 + epsilon)