diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 2db7c79..2025d21 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -28,7 +28,7 @@ repos:
   rev: 24.1.1
   hooks:
   - id: black
-    args: [--safe, --quiet, --line-length=100]
+    args: [--safe, --quiet, --line-length=100, --preview]
 - repo: https://github.com/PyCQA/autoflake
   rev: v2.2.1
   hooks:
diff --git a/tests/test_classify.py b/tests/test_classify.py
index ec31ae2..a857fb6 100644
--- a/tests/test_classify.py
+++ b/tests/test_classify.py
@@ -2,7 +2,9 @@
 
 
 def test_equation():
-    text = r"""
+    texts = []
+
+    t = r"""
 foo bar
 \begin{equation}
     \label{eq:foo}
@@ -10,24 +12,21 @@ def test_equation():
 \end{equation}
 baz
 """
+    texts.append(t)
 
-    tex = texplain.TeX(text)
-    tex.format_labels()
-    assert str(tex).strip() == text.strip()
-
-    # --
-
-    text = r"""
+    t = r"""
 My text
 \begin{equation}
     a = b
     \label{eq:qew}
 \end{equation}
 """
+    texts.append(t)
 
-    tex = texplain.TeX(text)
-    tex.format_labels()
-    assert str(tex).strip() == text.strip()
+    for text in texts:
+        tex = texplain.TeX(text)
+        tex.format_labels()
+        assert str(tex).strip() == text.strip()
 
 
 def test_section():
@@ -37,7 +36,6 @@ def test_section():
 \label{sec:foo}
 baz
 """
-
     tex = texplain.TeX(text)
     tex.format_labels()
     assert str(tex).strip() == text.strip()
@@ -52,7 +50,6 @@ def test_figure():
 \end{figure}
 baz
 """
-
     tex = texplain.TeX(text)
     tex.format_labels()
     assert str(tex).strip() == text.strip()
@@ -67,14 +64,15 @@ def test_figure_b():
 \end{figure*}
 baz
 """
-
     tex = texplain.TeX(text)
     tex.format_labels()
     assert str(tex).strip() == text.strip()
 
 
 def test_custom():
-    text = r"""
+    texts = []
+
+    t0 = r"""
 \begin{example}[H]
     \begin{oframed}
         \caption{Self-explanatory vs documentation intensive}
@@ -82,49 +80,35 @@ def test_custom():
     \end{oframed}
 \end{example}
 """
+    texts.append(t0)
 
-    tex = texplain.TeX(text)
-    tex.format_labels()
-    assert str(tex).strip() == text.strip()
+    texts.append("\n\n".join([r"\section{My section}"]) + t0)
+    texts.append("\n\n".join([r"\section{My section}", r"\label{sec:mysec}"]) + t0)
 
+    for text in texts:
+        tex = texplain.TeX(text)
+        tex.format_labels()
+        assert str(tex).strip() == text.strip()
 
-def test_custom_nested():
-    text = r"""
-\section{My section}
-
-\begin{example}[H]
-    \begin{oframed}
-        \caption{Self-explanatory vs documentation intensive}
-        \label{misc:self-explenatory}
-    \end{oframed}
-\end{example}
-"""
 
-    tex = texplain.TeX(text)
-    tex.format_labels()
-    assert str(tex).strip() == text.strip()
+def test_nested():
+    texts = []
 
+    t = r"""
+\begin{appendices}
 
-def test_custom_nested2():
-    text = r"""
-\section{My section}
-\label{sec:mysec}
+    \section{My section}
 
-\begin{example}[H]
-    \begin{oframed}
+    \begin{figure}[H]
         \caption{Self-explanatory vs documentation intensive}
-        \label{misc:self-explenatory}
-    \end{oframed}
-\end{example}
-"""
-
-    tex = texplain.TeX(text)
-    tex.format_labels()
-    assert str(tex).strip() == text.strip()
+        \label{fig:self-explenatory}
+    \end{figure}
 
+\end{appendices}
+"""
+    texts.append(t)
 
-def test_nested():
-    text = r"""
+    t = r"""
 \begin{appendices}
 
     \section{My section}
@@ -137,14 +121,9 @@ def test_nested():
 
 \end{appendices}
 """
+    texts.append(t)
 
-    tex = texplain.TeX(text)
-    tex.format_labels()
-    assert str(tex).strip() == text.strip()
-
-
-def test_nested_custom():
-    text = r"""
+    t = r"""
 \begin{appendices}
 
     \section{My section}
@@ -159,14 +138,18 @@ def test_nested_custom():
 
 \end{appendices}
 """
+    texts.append(t)
 
-    tex = texplain.TeX(text)
-    tex.format_labels()
-    assert str(tex).strip() == text.strip()
+    for text in texts:
+        tex = texplain.TeX(text)
+        tex.format_labels()
+        assert str(tex).strip() == text.strip()
 
 
 def test_hybrid():
-    text = r"""
+    texts = []
+
+    t = r"""
 \begin{itemize}
     \item
     \begin{referee}
@@ -185,14 +168,9 @@ def test_hybrid():
     \end{figure}
 \end{itemize}
 """
+    texts.append(t)
 
-    tex = texplain.TeX(text)
-    tex.format_labels()
-    assert str(tex).strip() == text.strip()
-
-    # ---
-
-    text = r"""
+    t = r"""
 Foo bar
 
 \section{My section}
@@ -210,7 +188,9 @@ def test_hybrid():
     \label{fig:1}
 \end{figure}
 """
+    texts.append(t)
 
-    tex = texplain.TeX(text)
-    tex.format_labels()
-    assert str(tex).strip() == text.strip()
+    for text in texts:
+        tex = texplain.TeX(text)
+        tex.format_labels()
+        assert str(tex).strip() == text.strip()
diff --git a/tests/test_simple.py b/tests/test_simple.py
index 19a677a..f53952b 100644
--- a/tests/test_simple.py
+++ b/tests/test_simple.py
@@ -453,31 +453,23 @@ def test_remove_command_d():
 def test_fix_quote():
     test = []
     test.append(['This is text "with quotes".', "This is text ``with quotes''."])
-    test.append(
-        [
-            'This is text "with quotes" but not matching".',
-            'This is text "with quotes" but not matching".',
-        ]
-    )
+    test.append([
+        'This is text "with quotes" but not matching".',
+        'This is text "with quotes" but not matching".',
+    ])
     test.append(["This is text 'with quotes'.", "This is text `with quotes'."])
-    test.append(
-        [
-            "This is text 'with quotes' but not matching'.",
-            "This is text 'with quotes' but not matching'.",
-        ]
-    )
-    test.append(
-        [
-            'A text "with one quote", and "another one".',
-            "A text ``with one quote'', and ``another one''.",
-        ]
-    )
-    test.append(
-        [
-            'A text "with one quote", and "another one"',
-            "A text ``with one quote'', and ``another one''",
-        ]
-    )
+    test.append([
+        "This is text 'with quotes' but not matching'.",
+        "This is text 'with quotes' but not matching'.",
+    ])
+    test.append([
+        'A text "with one quote", and "another one".',
+        "A text ``with one quote'', and ``another one''.",
+    ])
+    test.append([
+        'A text "with one quote", and "another one"',
+        "A text ``with one quote'', and ``another one''",
+    ])
     test.append(['Foo bar "bar foo"', "Foo bar ``bar foo''"])
 
     for source, expect in test: