diff --git a/src/scmrepo/git/credentials.py b/src/scmrepo/git/credentials.py
index 963c1c07..04a87f9f 100644
--- a/src/scmrepo/git/credentials.py
+++ b/src/scmrepo/git/credentials.py
@@ -164,6 +164,8 @@ def get(self, **kwargs) -> "Credential":
                 credentials[key] = value
             except ValueError:
                 continue
+        if not credentials:
+            raise CredentialNotFoundError("No credentials found")
         return Credential(**credentials)
 
     def store(self, **kwargs):
@@ -367,6 +369,11 @@ def __init__(
             self.username = self.username or parsed.username
             self.password = self.password or parsed.password
 
+    def __eq__(self, other: object) -> bool:
+        if isinstance(other, Credential):
+            return self._helper_kwargs == other._helper_kwargs
+        return False
+
     @property
     def url(self) -> str:
         if self.username or self.password:
diff --git a/tests/test_credentials.py b/tests/test_credentials.py
new file mode 100644
index 00000000..4b8df28a
--- /dev/null
+++ b/tests/test_credentials.py
@@ -0,0 +1,64 @@
+import os
+
+import pytest
+
+from scmrepo.git.credentials import (
+    Credential,
+    CredentialNotFoundError,
+    GitCredentialHelper,
+)
+
+
+@pytest.fixture(name="helper")
+def helper_fixture(mocker) -> "GitCredentialHelper":
+    mocker.patch("shutil.which", return_value="/usr/bin/git-credential-foo")
+    return GitCredentialHelper("foo")
+
+
+def test_subprocess_get(helper, mocker):
+    run = mocker.patch(
+        "subprocess.run",
+        return_value=mocker.Mock(
+            stdout=os.linesep.join(
+                ["protocol=https", "host=foo.com", "username=foo", "password=bar", ""]
+            )
+        ),
+    )
+    creds = helper.get(protocol="https", host="foo.com")
+    assert run.call_args.args[0] == ["git-credential-foo", "get"]
+    assert run.call_args.kwargs.get("input") == os.linesep.join(
+        ["protocol=https", "host=foo.com", ""]
+    )
+    assert creds == Credential(url="https://foo:bar@foo.com")
+
+
+def test_subprocess_get_failed(helper, mocker):
+    from subprocess import CalledProcessError
+
+    mocker.patch("subprocess.run", side_effect=CalledProcessError(1, "/usr/bin/foo"))
+    with pytest.raises(CredentialNotFoundError):
+        helper.get(protocol="https", host="foo.com")
+
+
+def test_subprocess_get_no_output(helper, mocker):
+    mocker.patch("subprocess.run", return_value=mocker.Mock(stdout=os.linesep))
+    with pytest.raises(CredentialNotFoundError):
+        helper.get(protocol="https", host="foo.com")
+
+
+def test_subprocess_store(helper, mocker):
+    run = mocker.patch("subprocess.run")
+    helper.store(protocol="https", host="foo.com", username="foo", password="bar")
+    assert run.call_args.args[0] == ["git-credential-foo", "store"]
+    assert run.call_args.kwargs.get("input") == os.linesep.join(
+        ["protocol=https", "host=foo.com", "username=foo", "password=bar", ""]
+    )
+
+
+def test_subprocess_erase(helper, mocker):
+    run = mocker.patch("subprocess.run")
+    helper.erase(protocol="https", host="foo.com")
+    assert run.call_args.args[0] == ["git-credential-foo", "erase"]
+    assert run.call_args.kwargs.get("input") == os.linesep.join(
+        ["protocol=https", "host=foo.com", ""]
+    )