diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index f733a39804..62c76d43c9 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -51,6 +51,7 @@ Test fixtures for use by clients are available for each release on the [Github r
 - ✨ Add a helper class `ethereum_test_tools.TestParameterGroup` to define test parameters as dataclasses and auto-generate test IDs ([#364](https://github.com/ethereum/execution-spec-tests/pull/364)).
 - 🔀 Change custom exception classes to dataclasses to improve testability ([#386](https://github.com/ethereum/execution-spec-tests/pull/386)).
 - 🔀 Updates fork name from Merge to Paris ([#363](https://github.com/ethereum/execution-spec-tests/pull/363)).
+- ✨ Add framework unit tests for post state exception verification ([#350](https://github.com/ethereum/execution-spec-tests/pull/350)).
 
 ### 🔧 EVM Tools
 
diff --git a/src/ethereum_test_tools/common/types.py b/src/ethereum_test_tools/common/types.py
index 7d79c45cf3..19fd41b3c4 100644
--- a/src/ethereum_test_tools/common/types.py
+++ b/src/ethereum_test_tools/common/types.py
@@ -500,7 +500,7 @@ def must_contain(self, address: str, other: "Storage"):
                     raise Storage.MissingKey(key=key)
             elif self.data[key] != other.data[key]:
                 raise Storage.KeyValueMismatch(
-                    address=address, key=key, got=self.data[key], want=other.data[key]
+                    address=address, key=key, want=self.data[key], got=other.data[key]
                 )
 
     def must_be_equal(self, address: str, other: "Storage"):
@@ -511,7 +511,7 @@ def must_be_equal(self, address: str, other: "Storage"):
         for key in self.data.keys() & other.data.keys():
             if self.data[key] != other.data[key]:
                 raise Storage.KeyValueMismatch(
-                    address=address, key=key, got=self.data[key], want=other.data[key]
+                    address=address, key=key, want=self.data[key], got=other.data[key]
                 )
 
         # Test keys contained in either one of the storage objects
diff --git a/src/ethereum_test_tools/tests/test_filling/__init__.py b/src/ethereum_test_tools/tests/test_filling/__init__.py
new file mode 100644
index 0000000000..7ae47ad3a8
--- /dev/null
+++ b/src/ethereum_test_tools/tests/test_filling/__init__.py
@@ -0,0 +1,3 @@
+"""
+`ethereum_test_tools.filling` verification tests.
+"""
diff --git a/src/ethereum_test_tools/tests/test_fixtures/blockchain_london_invalid_filled.json b/src/ethereum_test_tools/tests/test_filling/fixtures/blockchain_london_invalid_filled.json
similarity index 100%
rename from src/ethereum_test_tools/tests/test_fixtures/blockchain_london_invalid_filled.json
rename to src/ethereum_test_tools/tests/test_filling/fixtures/blockchain_london_invalid_filled.json
diff --git a/src/ethereum_test_tools/tests/test_fixtures/blockchain_london_valid_filled.json b/src/ethereum_test_tools/tests/test_filling/fixtures/blockchain_london_valid_filled.json
similarity index 100%
rename from src/ethereum_test_tools/tests/test_fixtures/blockchain_london_valid_filled.json
rename to src/ethereum_test_tools/tests/test_filling/fixtures/blockchain_london_valid_filled.json
diff --git a/src/ethereum_test_tools/tests/test_fixtures/blockchain_shanghai_invalid_filled_hive.json b/src/ethereum_test_tools/tests/test_filling/fixtures/blockchain_shanghai_invalid_filled_hive.json
similarity index 100%
rename from src/ethereum_test_tools/tests/test_fixtures/blockchain_shanghai_invalid_filled_hive.json
rename to src/ethereum_test_tools/tests/test_filling/fixtures/blockchain_shanghai_invalid_filled_hive.json
diff --git a/src/ethereum_test_tools/tests/test_fixtures/blockchain_shanghai_valid_filled_hive.json b/src/ethereum_test_tools/tests/test_filling/fixtures/blockchain_shanghai_valid_filled_hive.json
similarity index 100%
rename from src/ethereum_test_tools/tests/test_fixtures/blockchain_shanghai_valid_filled_hive.json
rename to src/ethereum_test_tools/tests/test_filling/fixtures/blockchain_shanghai_valid_filled_hive.json
diff --git a/src/ethereum_test_tools/tests/test_fixtures/chainid_istanbul_blockchain_test.json b/src/ethereum_test_tools/tests/test_filling/fixtures/chainid_istanbul_blockchain_test.json
similarity index 100%
rename from src/ethereum_test_tools/tests/test_fixtures/chainid_istanbul_blockchain_test.json
rename to src/ethereum_test_tools/tests/test_filling/fixtures/chainid_istanbul_blockchain_test.json
diff --git a/src/ethereum_test_tools/tests/test_fixtures/chainid_london_blockchain_test.json b/src/ethereum_test_tools/tests/test_filling/fixtures/chainid_london_blockchain_test.json
similarity index 100%
rename from src/ethereum_test_tools/tests/test_fixtures/chainid_london_blockchain_test.json
rename to src/ethereum_test_tools/tests/test_filling/fixtures/chainid_london_blockchain_test.json
diff --git a/src/ethereum_test_tools/tests/test_fixtures/chainid_paris_blockchain_test_hive.json b/src/ethereum_test_tools/tests/test_filling/fixtures/chainid_paris_blockchain_test_hive.json
similarity index 100%
rename from src/ethereum_test_tools/tests/test_fixtures/chainid_paris_blockchain_test_hive.json
rename to src/ethereum_test_tools/tests/test_filling/fixtures/chainid_paris_blockchain_test_hive.json
diff --git a/src/ethereum_test_tools/tests/test_fixtures/chainid_paris_state_test.json b/src/ethereum_test_tools/tests/test_filling/fixtures/chainid_paris_state_test.json
similarity index 100%
rename from src/ethereum_test_tools/tests/test_fixtures/chainid_paris_state_test.json
rename to src/ethereum_test_tools/tests/test_filling/fixtures/chainid_paris_state_test.json
diff --git a/src/ethereum_test_tools/tests/test_fixtures/chainid_shanghai_blockchain_test_hive.json b/src/ethereum_test_tools/tests/test_filling/fixtures/chainid_shanghai_blockchain_test_hive.json
similarity index 100%
rename from src/ethereum_test_tools/tests/test_fixtures/chainid_shanghai_blockchain_test_hive.json
rename to src/ethereum_test_tools/tests/test_filling/fixtures/chainid_shanghai_blockchain_test_hive.json
diff --git a/src/ethereum_test_tools/tests/test_fixtures/chainid_shanghai_state_test.json b/src/ethereum_test_tools/tests/test_filling/fixtures/chainid_shanghai_state_test.json
similarity index 100%
rename from src/ethereum_test_tools/tests/test_fixtures/chainid_shanghai_state_test.json
rename to src/ethereum_test_tools/tests/test_filling/fixtures/chainid_shanghai_state_test.json
diff --git a/src/ethereum_test_tools/tests/test_filling/test_expect.py b/src/ethereum_test_tools/tests/test_filling/test_expect.py
new file mode 100644
index 0000000000..02b0a3ee0c
--- /dev/null
+++ b/src/ethereum_test_tools/tests/test_filling/test_expect.py
@@ -0,0 +1,235 @@
+"""
+Test fixture post state (expect section) during state fixture generation.
+"""
+from typing import Any, Mapping
+
+import pytest
+
+from ethereum_test_forks import Fork, get_deployed_forks
+from evm_transition_tool import FixtureFormats, GethTransitionTool
+
+from ...common import Account, Environment, Transaction, to_address
+from ...common.types import Storage
+from ...spec import StateTest
+
+ADDRESS_UNDER_TEST = to_address(0x01)
+
+
+@pytest.fixture
+def pre(request) -> Mapping[Any, Any]:
+    """
+    The pre state: Set from the test's indirectly parametrized `pre` parameter.
+    """
+    return request.param
+
+
+@pytest.fixture
+def post(request) -> Mapping[Any, Any]:  # noqa: D103
+    """
+    The post state: Set from the test's indirectly parametrized `post` parameter.
+    """
+    return request.param
+
+
+@pytest.fixture
+def fork() -> Fork:  # noqa: D103
+    return get_deployed_forks()[-1]
+
+
+@pytest.fixture
+def state_test(  # noqa: D103
+    fork: Fork, pre: Mapping[Any, Any], post: Mapping[Any, Any]
+) -> StateTest:
+    return StateTest(
+        env=Environment(),
+        pre=pre,
+        post=post,
+        tx=Transaction(),
+        tag="post_value_mismatch",
+        fixture_format=FixtureFormats.STATE_TEST,
+    )
+
+
+@pytest.fixture
+def t8n() -> GethTransitionTool:  # noqa: D103
+    return GethTransitionTool()
+
+
+# Storage value mismatch tests
+@pytest.mark.parametrize(
+    "pre,post,expected_exception",
+    [
+        (  # mismatch_1: 1:1 vs 1:2
+            {ADDRESS_UNDER_TEST: Account(storage={"0x01": "0x01"}, nonce=1)},
+            {ADDRESS_UNDER_TEST: Account(storage={"0x01": "0x02"})},
+            Storage.KeyValueMismatch(address=ADDRESS_UNDER_TEST, key=1, want=2, got=1),
+        ),
+        (  # mismatch_2: 1:1 vs 2:1
+            {ADDRESS_UNDER_TEST: Account(storage={"0x01": "0x01"}, nonce=1)},
+            {ADDRESS_UNDER_TEST: Account(storage={"0x02": "0x01"})},
+            Storage.KeyValueMismatch(address=ADDRESS_UNDER_TEST, key=1, want=0, got=1),
+        ),
+        (  # mismatch_2_a: 1:1 vs 0:0
+            {ADDRESS_UNDER_TEST: Account(storage={"0x01": "0x01"}, nonce=1)},
+            {ADDRESS_UNDER_TEST: Account(storage={"0x00": "0x00"})},
+            Storage.KeyValueMismatch(address=ADDRESS_UNDER_TEST, key=1, want=0, got=1),
+        ),
+        (  # mismatch_2_b: 1:1 vs empty
+            {ADDRESS_UNDER_TEST: Account(storage={"0x01": "0x01"}, nonce=1)},
+            {ADDRESS_UNDER_TEST: Account(storage={})},
+            Storage.KeyValueMismatch(address=ADDRESS_UNDER_TEST, key=1, want=0, got=1),
+        ),
+        (  # mismatch_3: 0:0 vs 1:2
+            {ADDRESS_UNDER_TEST: Account(storage={"0x00": "0x00"}, nonce=1)},
+            {ADDRESS_UNDER_TEST: Account(storage={"0x01": "0x02"})},
+            Storage.KeyValueMismatch(address=ADDRESS_UNDER_TEST, key=1, want=2, got=0),
+        ),
+        (  # mismatch_3_a: empty vs 1:2
+            {ADDRESS_UNDER_TEST: Account(storage={}, nonce=1)},
+            {ADDRESS_UNDER_TEST: Account(storage={"0x01": "0x02"})},
+            Storage.KeyValueMismatch(address=ADDRESS_UNDER_TEST, key=1, want=2, got=0),
+        ),
+        (  # mismatch_4: 0:3, 1:2 vs 1:2
+            {ADDRESS_UNDER_TEST: Account(storage={"0x00": "0x03", "0x01": "0x02"}, nonce=1)},
+            {ADDRESS_UNDER_TEST: Account(storage={"0x01": "0x02"})},
+            Storage.KeyValueMismatch(address=ADDRESS_UNDER_TEST, key=0, want=0, got=3),
+        ),
+        (  # mismatch_5: 1:2, 2:3 vs 1:2
+            {ADDRESS_UNDER_TEST: Account(storage={"0x01": "0x02", "0x02": "0x03"}, nonce=1)},
+            {ADDRESS_UNDER_TEST: Account(storage={"0x01": "0x02"})},
+            Storage.KeyValueMismatch(address=ADDRESS_UNDER_TEST, key=2, want=0, got=3),
+        ),
+        (  # mismatch_6: 1:2 vs 1:2, 2:3
+            {ADDRESS_UNDER_TEST: Account(storage={"0x01": "0x02"}, nonce=1)},
+            {ADDRESS_UNDER_TEST: Account(storage={"0x01": "0x02", "0x02": "0x03"})},
+            Storage.KeyValueMismatch(address=ADDRESS_UNDER_TEST, key=2, want=3, got=0),
+        ),
+    ],
+)
+def test_post_storage_value_mismatch(pre, post, expected_exception, state_test, t8n, fork):
+    """
+    Test post state `Account.storage` exceptions during state test fixture generation.
+    """
+    with pytest.raises(Storage.KeyValueMismatch) as e_info:
+        state_test.generate(t8n=t8n, fork=fork)
+    assert e_info.value == expected_exception
+
+
+# Nonce value mismatch tests
+@pytest.mark.parametrize(
+    "pre,post",
+    [
+        ({ADDRESS_UNDER_TEST: Account(nonce=1)}, {ADDRESS_UNDER_TEST: Account(nonce=2)}),
+        ({ADDRESS_UNDER_TEST: Account(nonce=1)}, {ADDRESS_UNDER_TEST: Account(nonce=0)}),
+        ({ADDRESS_UNDER_TEST: Account(nonce=1)}, {ADDRESS_UNDER_TEST: Account(nonce=None)}),
+    ],
+)
+def test_post_nonce_value_mismatch(pre, post, state_test, t8n, fork):
+    """
+    Test post state `Account.nonce` verification and exceptions during state test
+    fixture generation.
+    """
+    pre_nonce = pre[ADDRESS_UNDER_TEST].nonce
+    post_nonce = post[ADDRESS_UNDER_TEST].nonce
+    if post_nonce is None:  # no exception
+        state_test.generate(t8n=t8n, fork=fork)
+        return
+    with pytest.raises(Account.NonceMismatch) as e_info:
+        state_test.generate(t8n=t8n, fork=fork)
+    assert e_info.value == Account.NonceMismatch(
+        address=ADDRESS_UNDER_TEST, want=post_nonce, got=pre_nonce
+    )
+
+
+# Code value mismatch tests
+@pytest.mark.parametrize(
+    "pre,post",
+    [
+        ({ADDRESS_UNDER_TEST: Account(code="0x02")}, {ADDRESS_UNDER_TEST: Account(code="0x01")}),
+        ({ADDRESS_UNDER_TEST: Account(code="0x02")}, {ADDRESS_UNDER_TEST: Account(code="0x")}),
+        ({ADDRESS_UNDER_TEST: Account(code="0x02")}, {ADDRESS_UNDER_TEST: Account(code=None)}),
+    ],
+    indirect=["pre", "post"],
+)
+def test_post_code_value_mismatch(pre, post, state_test, t8n, fork):
+    """
+    Test post state `Account.code` verification and exceptions during state test
+    fixture generation.
+    """
+    pre_code = pre[ADDRESS_UNDER_TEST].code
+    post_code = post[ADDRESS_UNDER_TEST].code
+    if post_code is None:  # no exception
+        state_test.generate(t8n=t8n, fork=fork)
+        return
+    with pytest.raises(Account.CodeMismatch) as e_info:
+        state_test.generate(t8n=t8n, fork=fork)
+    assert e_info.value == Account.CodeMismatch(
+        address=ADDRESS_UNDER_TEST, want=post_code, got=pre_code
+    )
+
+
+# Balance value mismatch tests
+@pytest.mark.parametrize(
+    "pre,post",
+    [
+        ({ADDRESS_UNDER_TEST: Account(balance=1)}, {ADDRESS_UNDER_TEST: Account(balance=2)}),
+        ({ADDRESS_UNDER_TEST: Account(balance=1)}, {ADDRESS_UNDER_TEST: Account(balance=0)}),
+        ({ADDRESS_UNDER_TEST: Account(balance=1)}, {ADDRESS_UNDER_TEST: Account(balance=None)}),
+    ],
+    indirect=["pre", "post"],
+)
+def test_post_balance_value_mismatch(pre, post, state_test, t8n, fork):
+    """
+    Test post state `Account.balance` verification and exceptions during state test
+    fixture generation.
+    """
+    pre_balance = pre[ADDRESS_UNDER_TEST].balance
+    post_balance = post[ADDRESS_UNDER_TEST].balance
+    if post_balance is None:  # no exception
+        state_test.generate(t8n=t8n, fork=fork)
+        return
+    with pytest.raises(Account.BalanceMismatch) as e_info:
+        state_test.generate(t8n=t8n, fork=fork)
+    assert e_info.value == Account.BalanceMismatch(
+        address=ADDRESS_UNDER_TEST, want=post_balance, got=pre_balance
+    )
+
+
+# Account mismatch tests
+@pytest.mark.parametrize(
+    "pre,post,error_str",
+    [
+        (
+            {ADDRESS_UNDER_TEST: Account(balance=1)},
+            {ADDRESS_UNDER_TEST: Account()},
+            None,
+        ),
+        (
+            {ADDRESS_UNDER_TEST: Account(balance=1)},
+            {ADDRESS_UNDER_TEST: Account(balance=1), to_address(0x02): Account(balance=1)},
+            "expected account not found",
+        ),
+        (
+            {ADDRESS_UNDER_TEST: Account(balance=1)},
+            {},
+            None,
+        ),
+        (
+            {ADDRESS_UNDER_TEST: Account(balance=1)},
+            {ADDRESS_UNDER_TEST: Account.NONEXISTENT},
+            "found unexpected account",
+        ),
+    ],
+    indirect=["pre", "post"],
+)
+def test_post_account_mismatch(state_test, t8n, fork, error_str):
+    """
+    Test post state `Account` verification and exceptions during state test
+    fixture generation.
+    """
+    if error_str is None:
+        state_test.generate(t8n=t8n, fork=fork)
+        return
+    with pytest.raises(Exception) as e_info:
+        state_test.generate(t8n=t8n, fork=fork)
+    assert error_str in str(e_info.value)
diff --git a/src/ethereum_test_tools/tests/test_filler.py b/src/ethereum_test_tools/tests/test_filling/test_fixtures.py
similarity index 97%
rename from src/ethereum_test_tools/tests/test_filler.py
rename to src/ethereum_test_tools/tests/test_filling/test_fixtures.py
index 3b845833ea..89c32e9d8f 100644
--- a/src/ethereum_test_tools/tests/test_filler.py
+++ b/src/ethereum_test_tools/tests/test_filling/test_fixtures.py
@@ -1,5 +1,5 @@
 """
-Test suite for `ethereum_test` module.
+Test suite for `ethereum_test_tools.filling` fixture generation.
 """
 
 import json
@@ -12,13 +12,13 @@
 from ethereum_test_forks import Berlin, Fork, Istanbul, London, Paris, Shanghai
 from evm_transition_tool import FixtureFormats, GethTransitionTool
 
-from ..code import Yul
-from ..common import Account, Environment, TestAddress, Transaction, to_json
-from ..spec import BlockchainTest, StateTest
-from ..spec.blockchain.types import Block
-from ..spec.blockchain.types import Fixture as BlockchainFixture
-from ..spec.blockchain.types import FixtureCommon as BlockchainFixtureCommon
-from .conftest import SOLC_PADDING_VERSION
+from ...code import Yul
+from ...common import Account, Environment, TestAddress, Transaction, to_json
+from ...spec import BlockchainTest, StateTest
+from ...spec.blockchain.types import Block
+from ...spec.blockchain.types import Fixture as BlockchainFixture
+from ...spec.blockchain.types import FixtureCommon as BlockchainFixtureCommon
+from ..conftest import SOLC_PADDING_VERSION
 
 
 def remove_info(fixture_json: Dict[str, Any]):  # noqa: D103
@@ -161,7 +161,8 @@ def test_fill_state_test(
             "src",
             "ethereum_test_tools",
             "tests",
-            "test_fixtures",
+            "test_filling",
+            "fixtures",
             expected_json_file,
         )
     ) as f:
@@ -461,7 +462,8 @@ def test_fill_blockchain_valid_txs(
             "src",
             "ethereum_test_tools",
             "tests",
-            "test_fixtures",
+            "test_filling",
+            "fixtures",
             expected_json_file,
         )
     ) as f:
@@ -810,7 +812,8 @@ def test_fill_blockchain_invalid_txs(
             "src",
             "ethereum_test_tools",
             "tests",
-            "test_fixtures",
+            "test_filling",
+            "fixtures",
             expected_json_file,
         )
     ) as f: