diff --git a/src/hermes/model/context_manager.py b/src/hermes/model/context_manager.py
index e6975481..0c641619 100644
--- a/src/hermes/model/context_manager.py
+++ b/src/hermes/model/context_manager.py
@@ -55,10 +55,18 @@ def prepare_step(self, step: str, *depends: str) -> None:
         self._current_step.append(step)
 
     def finalize_step(self, step: str) -> None:
-        current_step = self._current_step.pop()
-        if current_step != step:
-            raise ValueError("Cannot end step %s while in %s.", step, self._current_step[-1])
+        if len(self._current_step) < 1:
+            raise ValueError("There is no step to end.")
+        if self._current_step[-1] != step:
+            raise ValueError(f"Cannot end step {step} while in {self._current_step[-1]}.")
+        self._current_step.pop()
 
     def __getitem__(self, source_name: str) -> HermesCache:
+        if len(self._current_step) < 1:
+            raise HermesContexError("Prepare a step first.")
         subdir = self.cache_dir / self._current_step[-1] / source_name
         return HermesCache(subdir)
+
+
+class HermesContexError(Exception):
+    pass
diff --git a/test/__init__.py b/test/__init__.py
new file mode 100644
index 00000000..0e85f01e
--- /dev/null
+++ b/test/__init__.py
@@ -0,0 +1,3 @@
+# SPDX-FileCopyrightText: 2025 German Aerospace Center (DLR)
+#
+# SPDX-License-Identifier: Apache-2.0
diff --git a/test/hermes_test/__init__.py b/test/hermes_test/__init__.py
index faf5a2f5..0e85f01e 100644
--- a/test/hermes_test/__init__.py
+++ b/test/hermes_test/__init__.py
@@ -1,3 +1,3 @@
-# SPDX-FileCopyrightText: 2022 German Aerospace Center (DLR)
+# SPDX-FileCopyrightText: 2025 German Aerospace Center (DLR)
 #
 # SPDX-License-Identifier: Apache-2.0
diff --git a/test/hermes_test/model/test_base_context.py b/test/hermes_test/model/test_base_context.py
deleted file mode 100644
index bdf016b7..00000000
--- a/test/hermes_test/model/test_base_context.py
+++ /dev/null
@@ -1,38 +0,0 @@
-# SPDX-FileCopyrightText: 2022 German Aerospace Center (DLR)
-#
-# SPDX-License-Identifier: Apache-2.0
-
-# SPDX-FileContributor: Michael Meinel
-
-from pathlib import Path
-
-from hermes.model.context import HermesContext
-
-
-def test_context_hermes_dir_default():
-    ctx = HermesContext()
-    assert ctx.hermes_dir == Path('.') / '.hermes'
-
-
-def test_context_hermes_dir_custom():
-    ctx = HermesContext('spam')
-    assert ctx.hermes_dir == Path('spam') / '.hermes'
-
-
-def test_context_get_cache_default():
-    ctx = HermesContext()
-    assert ctx.get_cache('spam', 'eggs') == Path('.') / '.hermes' / 'spam' / 'eggs.json'
-
-
-def test_context_get_cache_cached():
-    ctx = HermesContext()
-    ctx._caches[('spam', 'eggs')] = Path('spam_and_eggs')
-    assert ctx.get_cache('spam', 'eggs') == Path('spam_and_eggs')
-
-
-def test_context_get_cache_create(tmpdir):
-    ctx = HermesContext(tmpdir)
-    subdir = Path(tmpdir) / '.hermes' / 'spam'
-
-    assert ctx.get_cache('spam', 'eggs', create=True) == subdir / 'eggs.json'
-    assert subdir.exists()
diff --git a/test/hermes_test/model/test_context_manager.py b/test/hermes_test/model/test_context_manager.py
new file mode 100644
index 00000000..231e4df1
--- /dev/null
+++ b/test/hermes_test/model/test_context_manager.py
@@ -0,0 +1,87 @@
+# SPDX-FileCopyrightText: 2025 German Aerospace Center (DLR)
+#
+# SPDX-License-Identifier: Apache-2.0
+
+# SPDX-FileContributor: Michael Meinel
+# SPDX-FileContributor: Sophie Kernchen
+import pytest
+from pathlib import Path
+
+from hermes.model.context_manager import HermesContext, HermesCache, HermesContexError
+
+
+def test_context_hermes_dir_default():
+    ctx = HermesContext()
+    assert ctx.cache_dir == Path('./.hermes').absolute()
+
+
+def test_context_hermes_dir_custom():
+    ctx = HermesContext(Path('spam'))
+    assert ctx.cache_dir == Path('spam') / '.hermes'
+
+
+def test_get_context_default():
+    ctx = HermesContext()
+    ctx.prepare_step("ham")
+    assert ctx["spam"]._cache_dir == Path('./.hermes/ham/spam').absolute()
+
+
+def test_context_get_error():
+    ctx = HermesContext()
+    ctx.prepare_step("ham")
+    ctx.finalize_step("ham")
+    with pytest.raises(HermesContexError, match="Prepare a step first."):
+        ctx["spam"]._cache_dir == Path('./.hermes/spam').absolute()
+
+
+def test_finalize_context_one_item():
+    ctx = HermesContext()
+    ctx.prepare_step("ham")
+    ctx.finalize_step("ham")
+    assert ctx._current_step == []
+
+
+def test_finalize_context():
+    ctx = HermesContext()
+    ctx.prepare_step("ham")
+    ctx.prepare_step("spam")
+    ctx.finalize_step("spam")
+    assert ctx["spam"]._cache_dir == Path('./.hermes/ham/spam').absolute()
+    assert ctx._current_step == ["ham"]
+
+
+def test_finalize_context_error_no_item():
+    ctx = HermesContext()
+    with pytest.raises(ValueError, match="There is no step to end."):
+        ctx.finalize_step("spam")
+
+
+def test_finalize_context_error():
+    ctx = HermesContext()
+    ctx.prepare_step("ham")
+    with pytest.raises(ValueError, match="Cannot end step spam while in ham."):
+        ctx.finalize_step("spam")
+
+
+def test_cache(tmpdir):
+    ctx = HermesContext(Path(tmpdir))
+    ctx.prepare_step("ham")
+    with ctx["spam"] as c:
+        c["bacon"] = {"data": "goose", "num": 2}
+
+    path = tmpdir / Path('.hermes') / 'ham' / 'spam' / 'bacon.json'
+    assert path.exists()
+    assert path.read() == '{"data": "goose", "num": 2}'
+    assert c._cached_data["bacon"] == {"data": "goose", "num": 2}
+
+
+def test_hermes_cache_set(tmpdir):
+    cache = HermesCache(Path(tmpdir))
+    cache["bacon"] = "eggs"
+    assert cache._cached_data == {"bacon": "eggs"}
+
+
+def test_hermes_cache_get(tmpdir):
+    cache = HermesCache(Path(tmpdir))
+    cache._cached_data = {"bacon": "eggs"}
+    assert cache["bacon"] == "eggs"