Add more tests

python · JukkaL · Apr 1, 2026 · Apr 1, 2026 · Apr 1, 2026 · Apr 1, 2026
commit 3a1767d4b15840a0ba69676059c547d56c0cdb84
diff --git a/mypyc/test-data/run-vecs-i64-interp.test b/mypyc/test-data/run-vecs-i64-interp.test
@@ -417,3 +417,85 @@ def test_pop_index() -> None:
     v, n = pop(v, 0)
     assert n == 15
     assert v == vec[i64]()
+
+def test_cap_empty() -> None:
+    v = vec[i64](cap=3)
+    assert len(v) == 0
+    assert v == vec[i64]()
+
+def test_cap_with_initializer() -> None:
+    v = vec[i64]([10, 20], cap=3)
+    assert len(v) == 2
+    assert v[0] == 10
+    assert v[1] == 20
+    assert v == vec[i64]([10, 20])
+
+def test_cap_zero() -> None:
+    v = vec[i64](cap=0)
+    assert len(v) == 0
+    v = vec[i64]([5], cap=0)
+    assert v == vec[i64]([5])
+
+def test_cap_negative() -> None:
+    with assertRaises(ValueError):
+        vec[i64](cap=-1)
+    with assertRaises(ValueError):
+        vec[i64]([1], cap=-1)
+
+def test_cap_buffer_reuse_empty() -> None:
+    # cap=3, append 3 items -> all fit, buffer reused (no reallocation)
+    v = vec[i64](cap=3)
+    old = v
+    v = append(v, 1)
+    v = append(v, 2)
+    v = append(v, 3)
+    assert len(v) == 3
+    # old shares the buffer so old's append overwrites v[0]
+    old = append(old, 99)
+    assert v[0] == 99
+
+def test_cap_buffer_reuse_with_initializer() -> None:
+    # 2 items with cap=3 -> one more append fits without reallocation
+    v = vec[i64]([10, 20], cap=3)
+    old = v
+    v = append(v, 30)
+    assert len(v) == 3
+    # Shared buffer: mutation through v visible through old
+    v[0] = 99
+    assert old[0] == 99
+
+def test_cap_buffer_reuse_at_capacity() -> None:
+    # cap=2, fill with 2 items -> at capacity, next append must reallocate
+    v = vec[i64]([10, 20], cap=2)
+    old = v
+    v = append(v, 30)
+    # v now has a new buffer; appending to old should NOT affect v
+    old = append(old, 99)
+    assert v[0] == 10
+
+def test_cap_read_old_after_realloc() -> None:
+    # After reallocation, old alias must still have valid items
+    v = vec[i64]([10, 20, 30], cap=3)
+    old = v
+    v = append(v, 40)
+    v[0] = 99
+    assert old[0] == 10
+    assert old[1] == 20
+    assert old[2] == 30
+
+def test_cap_exceeded() -> None:
+    # cap=2, fill to capacity, then one more append triggers reallocation
+    v = vec[i64](cap=2)
+    v = append(v, 10)
+    v = append(v, 20)
+    old = v
+    v = append(v, 30)
+    old = append(old, 99)
+    assert v[0] == 10
+
+def test_cap_initializer_longer_than_cap() -> None:
+    v = vec[i64]([10, 20, 30], cap=1)
+    assert len(v) == 3
+    assert v[0] == 10
+    assert v[1] == 20
+    assert v[2] == 30
diff --git a/mypyc/test-data/run-vecs-misc-interp.test b/mypyc/test-data/run-vecs-misc-interp.test
@@ -453,6 +453,58 @@ def test_iterator_protocol() -> None:
     with assertRaises(StopIteration):
         next(it)
 
+def test_cap_empty() -> None:
+    for t in ITEM_TYPES:
+        v = vec[t](cap=3)
+        assert len(v) == 0
+        assert v == vec[t]()
+
+def test_cap_with_initializer() -> None:
+    v = vec[float]([1.5, 2.5], cap=3)
+    assert len(v) == 2
+    assert v[0] == 1.5
+    assert v[1] == 2.5
+
+    v = vec[u8]([10, 20], cap=3)
+    assert len(v) == 2
+    assert v[0] == 10
+
+    v = vec[i16]([-100, 100], cap=3)
+    assert len(v) == 2
+
+    v = vec[i32]([1000, 2000], cap=3)
+    assert len(v) == 2
+
+    v = vec[bool]([True, False], cap=3)
+    assert len(v) == 2
+    assert v[0] is True
+    assert v[1] is False
+
+def test_cap_negative() -> None:
+    for t in ITEM_TYPES:
+        with assertRaises(ValueError):
+            vec[t](cap=-1)
+
+def test_cap_buffer_reuse() -> None:
+    # Verify buffer reuse within cap for each type
+    v = vec[float]([1.5], cap=3)
+    old = v
+    v = append(v, 2.5)
+    v[0] = 9.5
+    assert old[0] == 9.5  # shared buffer
+
+    v = vec[u8]([10], cap=3)
+    old = v
+    v = append(v, 20)
+    v[0] = 99
+    assert old[0] == 99
+
+    v = vec[bool]([True], cap=3)
+    old = v
+    v = append(v, False)
+    v[0] = False
+    assert old[0] is False
+
 [case testLibrtVecsFeaturesNotAvailableInNonExperimentalBuild_librt]
 # This also ensures librt.vecs can be built without experimental features
 import librt.vecs

diff --git a/mypyc/test-data/run-vecs-nested-interp.test b/mypyc/test-data/run-vecs-nested-interp.test
@@ -467,3 +467,93 @@ def test_append_with_alias() -> None:
     assert len(alias) == 1
     assert v[0] == vec[i64]([1, 2, 3])
     assert len(v) == 4
+
+def test_cap_empty() -> None:
+    v = vec[vec[str]](cap=3)
+    assert len(v) == 0
+    assert v == vec[vec[str]]()
+
+def test_cap_with_initializer() -> None:
+    v = vec[vec[str]]([vec[str](['a']), vec[str](['b'])], cap=3)
+    assert len(v) == 2
+    assert v[0] == vec[str](['a'])
+    assert v[1] == vec[str](['b'])
+
+def test_cap_zero() -> None:
+    v = vec[vec[str]](cap=0)
+    assert len(v) == 0
+    v = vec[vec[str]]([vec[str](['x'])], cap=0)
+    assert v == vec[vec[str]]([vec[str](['x'])])
+
+def test_cap_negative() -> None:
+    with assertRaises(ValueError):
+        vec[vec[str]](cap=-1)
+    with assertRaises(ValueError):
+        vec[vec[str]]([vec[str]()], cap=-1)
+
+def test_cap_buffer_reuse_empty() -> None:
+    # cap=3, append 3 items -> all fit, buffer reused (no reallocation)
+    v = vec[vec[str]](cap=3)
+    old = v
+    v = append(v, vec[str](['a']))
+    v = append(v, vec[str](['b']))
+    v = append(v, vec[str](['c']))
+    assert len(v) == 3
+    # old shares the buffer so old's append overwrites v[0]
+    old = append(old, vec[str](['Q']))
+    assert v[0] == vec[str](['Q'])
+
+def test_cap_buffer_reuse_with_initializer() -> None:
+    # 2 items with cap=3 -> one more append fits without reallocation
+    v = vec[vec[str]]([vec[str](['a']), vec[str](['b'])], cap=3)
+    old = v
+    v = append(v, vec[str](['c']))
+    assert len(v) == 3
+    # Shared buffer: mutation through v visible through old
+    v[0] = vec[str](['z'])
+    assert old[0] == vec[str](['z'])
+
+def test_cap_buffer_reuse_at_capacity() -> None:
+    # cap=2, fill with 2 items -> at capacity, next append must reallocate
+    v = vec[vec[str]]([vec[str](['a']), vec[str](['b'])], cap=2)
+    old = v
+    v = append(v, vec[str](['c']))
+    # v now has a new buffer; appending to old should NOT affect v
+    old = append(old, vec[str](['Q']))
+    assert v[0] == vec[str](['a'])
+
+def test_cap_read_old_after_realloc() -> None:
+    # After reallocation, old alias must still have valid items (not NULL)
+    v = vec[vec[str]]([vec[str](['a']), vec[str](['b']), vec[str](['c'])], cap=3)
+    old = v
+    v = append(v, vec[str](['d']))
+    v[0] = vec[str](['z'])
+    assert old[0] == vec[str](['a'])
+    assert old[1] == vec[str](['b'])
+    assert old[2] == vec[str](['c'])
+
+def test_cap_exceeded() -> None:
+    # cap=2, fill to capacity, then one more append triggers reallocation
+    v = vec[vec[str]](cap=2)
+    v = append(v, vec[str](['a']))
+    v = append(v, vec[str](['b']))
+    old = v
+    v = append(v, vec[str](['c']))
+    old = append(old, vec[str](['Q']))
+    assert v[0] == vec[str](['a'])
+
+def test_cap_initializer_longer_than_cap() -> None:
+    v = vec[vec[str]]([vec[str](['a']), vec[str](['b']), vec[str](['c'])], cap=1)
+    assert len(v) == 3
+    assert v[0] == vec[str](['a'])
+    assert v[1] == vec[str](['b'])
+    assert v[2] == vec[str](['c'])
+
+def test_cap_nested_i64() -> None:
+    v = vec[vec[i64]](cap=3)
+    assert len(v) == 0
+    v = append(v, vec[i64]([1, 2]))
+    v = append(v, vec[i64]([3]))
+    assert len(v) == 2
+    assert v[0] == vec[i64]([1, 2])
+    assert v[1] == vec[i64]([3])