1 files changed, 47 insertions, 0 deletions
diff --git a/tests/builder/fork.test.py b/tests/builder/fork.test.py
new file mode 100644
index 0000000..bcb8d1b
--- /dev/null
+++ b/tests/builder/fork.test.py
@@ -0,0 +1,47 @@
+"""Tests for the :meth:`BuilderCore.fork` and :meth:`BuilderCore.copy` aliases."""
+
+from edify import Pattern, RegexBuilder
+
+
+def test_fork_returns_a_regex_builder_with_the_same_state():
+    original = RegexBuilder().digit()
+    forked = original.fork()
+    assert forked == original
+    assert forked is not original
+
+
+def test_fork_returns_a_pattern_with_the_same_state():
+    original = Pattern().word()
+    forked = original.fork()
+    assert forked == original
+    assert forked is not original
+
+
+def test_copy_returns_a_regex_builder_with_the_same_state():
+    original = RegexBuilder().digit()
+    copied = original.copy()
+    assert copied == original
+    assert copied is not original
+
+
+def test_copy_returns_a_pattern_with_the_same_state():
+    original = Pattern().word()
+    copied = original.copy()
+    assert copied == original
+    assert copied is not original
+
+
+def test_fork_and_copy_produce_independent_branches():
+    root = RegexBuilder().digit()
+    branch_a = root.fork().word()
+    branch_b = root.copy().whitespace_char()
+    assert root.to_regex_string() == "\\d"
+    assert branch_a.to_regex_string() == "\\d\\w"
+    assert branch_b.to_regex_string() == "\\d\\s"
+
+
+def test_fork_and_copy_return_the_concrete_class_type():
+    assert isinstance(RegexBuilder().fork(), RegexBuilder)
+    assert isinstance(RegexBuilder().copy(), RegexBuilder)
+    assert isinstance(Pattern().fork(), Pattern)
+    assert isinstance(Pattern().copy(), Pattern)