diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 07330be0..b9e79e57 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -34,6 +34,7 @@ repos:
      args: [--disable-error-code=has-type,--disable-error-code=import-not-found]
      additional_dependencies:
        [
+         "types-jsonschema~=4.21.0",
          "types-mock==5.0.*",
          "types-PyYAML==6.0",
          "types-toml~=0.10",
diff --git a/integration_tests/conftest.py b/integration_tests/conftest.py
index e69de29b..3f4f5fb2 100644
--- a/integration_tests/conftest.py
+++ b/integration_tests/conftest.py
@@ -0,0 +1,11 @@
+import json
+
+import pytest
+import requests
+
+
+@pytest.fixture(scope="module")
+def codetf_schema():
+    schema_path = "https://raw.githubusercontent.com/pixee/codemodder-specs/main/codetf.schema.json"
+    response = requests.get(schema_path)
+    yield json.loads(response.text)
diff --git a/pyproject.toml b/pyproject.toml
index b452dcf0..df548618 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -15,6 +15,7 @@ dependencies = [
     "isort>=5.12,<5.14",
     "libcst>=1.1,<1.3",
     "packaging>=23.2,<25.0",
+    "pydantic~=2.6.0",
     "pylint>=3.0,<3.2",
     "python-json-logger~=2.0.0",
     "PyYAML~=6.0.0",
@@ -50,6 +51,7 @@ test = [
     "coverage>=7.3,<7.5",
     "Flask<4",
     "Jinja2~=3.1.2",
+    "jsonschema~=4.21.0",
     "lxml>=4.9.3,<5.2.0",
     "mock==5.1.*",
     "pre-commit<4",
@@ -59,6 +61,7 @@ test = [
     "pytest-mock~=3.12.0",
     "pytest-randomly==3.*",
     "pytest-xdist==3.*",
+    "requests~=2.31.0",
     "security~=1.2.0",
     "types-mock==5.1.*",
     "django>=4,<6",
diff --git a/src/codemodder/change.py b/src/codemodder/change.py
deleted file mode 100644
index 25c012d7..00000000
--- a/src/codemodder/change.py
+++ /dev/null
@@ -1,71 +0,0 @@
-from dataclasses import dataclass, field
-from enum import Enum
-
-
-class Action(Enum):
-    ADD = "add"
-    REMOVE = "remove"
-
-
-class Result(Enum):
-    COMPLETED = "completed"
-    FAILED = "failed"
-    SKIPPED = "skipped"
-
-
-class DiffSide(Enum):
-    LEFT = "left"
-    RIGHT = "right"
-
-
-@dataclass
-class PackageAction:
-    action: Action
-    result: Result
-    package: str
-
-    def to_json(self):
-        return {
-            "action": self.action.value.upper(),
-            "result": self.result.value.upper(),
-            "package": self.package,
-        }
-
-
-@dataclass
-class Change:
-    lineNumber: int
-    description: str
-    # All of our changes are currently treated as additive, so it makes sense
-    # for the comments to appear on the RIGHT side of the split diff. Eventually we
-    # may want to differentiate between LEFT and RIGHT, but for now we'll just
-    # default to RIGHT.
-    diffSide: DiffSide = field(default=DiffSide.RIGHT)
-    properties: dict = field(default_factory=dict)
-    packageActions: list[PackageAction] = field(default_factory=list)
-
-    def to_json(self):
-        return {
-            # Not sure why this is a string but it's in the spec
-            "lineNumber": str(self.lineNumber),
-            "description": self.description,
-            "properties": self.properties,
-            "diffSide": self.diffSide.value.lower(),
-            "packageActions": [pa.to_json() for pa in self.packageActions],
-        }
-
-
-@dataclass
-class ChangeSet:
-    """A set of changes made to a file at `path`"""
-
-    path: str
-    diff: str
-    changes: list[Change]
-
-    def to_json(self):
-        return {
-            "path": self.path,
-            "diff": self.diff,
-            "changes": [x.to_json() for x in self.changes],
-        }
diff --git a/src/codemodder/codemodder.py b/src/codemodder/codemodder.py
index 4776a939..87363164 100644
--- a/src/codemodder/codemodder.py
+++ b/src/codemodder/codemodder.py
@@ -11,12 +11,12 @@
 from codemodder.code_directory import match_files
 from codemodder.codemods.api import BaseCodemod
 from codemodder.codemods.semgrep import SemgrepRuleDetector
+from codemodder.codetf import CodeTF
 from codemodder.context import CodemodExecutionContext
 from codemodder.dependency import Dependency
 from codemodder.logging import configure_logger, log_list, log_section, logger
 from codemodder.project_analysis.file_parsers.package_store import PackageStore
 from codemodder.project_analysis.python_repo_manager import PythonRepoManager
-from codemodder.report.codetf_reporter import report_default
 from codemodder.result import ResultSet
 from codemodder.sarifs import detect_sarif_tools
 from codemodder.semgrep import run as run_semgrep
@@ -210,13 +210,17 @@ def run(original_args) -> int:
         files_to_analyze,
     )
 
-    results = context.compile_results(codemods_to_run)
-
     elapsed = datetime.datetime.now() - start
     elapsed_ms = int(elapsed.total_seconds() * 1000)
 
     if argv.output:
-        report_default(elapsed_ms, argv, original_args, results)
+        codetf = CodeTF.build(
+            context,
+            elapsed_ms,
+            original_args,
+            context.compile_results(codemods_to_run),
+        )
+        codetf.write_report(argv.output)
 
     log_report(context, argv, elapsed_ms, files_to_analyze)
     return 0
diff --git a/src/codemodder/codemods/base_codemod.py b/src/codemodder/codemods/base_codemod.py
index e2398183..5b592012 100644
--- a/src/codemodder/codemods/base_codemod.py
+++ b/src/codemodder/codemods/base_codemod.py
@@ -11,6 +11,7 @@
 from codemodder.code_directory import file_line_patterns
 from codemodder.codemods.base_detector import BaseDetector
 from codemodder.codemods.base_transformer import BaseTransformerPipeline
+from codemodder.codetf import Reference
 from codemodder.context import CodemodExecutionContext
 from codemodder.file_context import FileContext
 from codemodder.logging import logger
@@ -23,18 +24,6 @@ class ReviewGuidance(Enum):
     MERGE_WITHOUT_REVIEW = 3
 
 
-@dataclass
-class Reference:
-    url: str
-    description: str = ""
-
-    def to_json(self):
-        return {
-            "url": self.url,
-            "description": self.description or self.url,
-        }
-
-
 @dataclass
 class Metadata:
     name: str
@@ -124,7 +113,7 @@ def describe(self):
             "codemod": self.id,
             "summary": self.summary,
             "description": self.description,
-            "references": [ref.to_json() for ref in self.references],
+            "references": [ref.model_dump() for ref in self.references],
         }
 
     def _apply(
diff --git a/src/codemodder/codemods/base_transformer.py b/src/codemodder/codemods/base_transformer.py
index fba16156..673af338 100644
--- a/src/codemodder/codemods/base_transformer.py
+++ b/src/codemodder/codemods/base_transformer.py
@@ -1,7 +1,7 @@
 from abc import ABCMeta, abstractmethod
 
-from codemodder.change import ChangeSet
 from codemodder.codemods.base_visitor import BaseTransformer
+from codemodder.codetf import ChangeSet
 from codemodder.context import CodemodExecutionContext
 from codemodder.file_context import FileContext
 from codemodder.result import Result
diff --git a/src/codemodder/codemods/imported_call_modifier.py b/src/codemodder/codemods/imported_call_modifier.py
index f1566928..4d1a371a 100644
--- a/src/codemodder/codemods/imported_call_modifier.py
+++ b/src/codemodder/codemods/imported_call_modifier.py
@@ -6,9 +6,9 @@
 from libcst.codemod import CodemodContext, VisitorBasedCodemodCommand
 from libcst.metadata import PositionProvider
 
-from codemodder.change import Change
 from codemodder.codemods.base_visitor import UtilsMixin
 from codemodder.codemods.utils_mixin import NameResolutionMixin
+from codemodder.codetf import Change
 from codemodder.file_context import FileContext
 from codemodder.result import Result
 
@@ -75,7 +75,7 @@ def leave_Call(self, original_node: cst.Call, updated_node: cst.Call):
                 and true_name in self.matching_functions
             ):
                 self.changes_in_file.append(
-                    Change(line_number, self.change_description)
+                    Change(lineNumber=line_number, description=self.change_description)
                 )
 
                 new_args = self.updated_args(updated_node.args)
diff --git a/src/codemodder/codemods/libcst_transformer.py b/src/codemodder/codemods/libcst_transformer.py
index 7df6c1a5..be50dc0d 100644
--- a/src/codemodder/codemods/libcst_transformer.py
+++ b/src/codemodder/codemods/libcst_transformer.py
@@ -1,4 +1,5 @@
 from collections import namedtuple
+from typing import cast
 
 import libcst as cst
 from libcst import matchers
@@ -6,10 +7,10 @@
 from libcst.codemod import CodemodContext
 from libcst.codemod.visitors import AddImportsVisitor, RemoveImportsVisitor
 
-from codemodder.change import Change, ChangeSet
 from codemodder.codemods.base_transformer import BaseTransformerPipeline
 from codemodder.codemods.base_visitor import BaseTransformer
 from codemodder.codemods.utils import get_call_name
+from codemodder.codetf import Change, ChangeSet
 from codemodder.context import CodemodExecutionContext
 from codemodder.dependency import Dependency
 from codemodder.diff import create_diff_from_tree
@@ -99,7 +100,7 @@ def leave_ClassDef(
 
     def node_position(self, node):
         # See https://github.com/Instagram/LibCST/blob/main/libcst/_metadata_dependent.py#L112
-        return self.get_metadata(self.METADATA_DEPENDENCIES[0], node)
+        return cast(CodeRange, self.get_metadata(self.METADATA_DEPENDENCIES[0], node))
 
     def add_change(self, node, description: str, start: bool = True):
         position = self.node_position(node)
@@ -125,7 +126,7 @@ def add_dependency(self, dependency: Dependency):
     def report_change(self, original_node):
         line_number = self.lineno_for_node(original_node)
         self.file_context.codemod_changes.append(
-            Change(line_number, self.change_description)
+            Change(lineNumber=line_number, description=self.change_description)
         )
 
     def remove_unused_import(self, original_node):
@@ -275,8 +276,8 @@ def apply(
             return None
 
         change_set = ChangeSet(
-            str(file_context.file_path.relative_to(context.directory)),
-            diff,
+            path=str(file_context.file_path.relative_to(context.directory)),
+            diff=diff,
             changes=file_context.codemod_changes,
         )
 
diff --git a/src/codemodder/codemods/test/integration_utils.py b/src/codemodder/codemods/test/integration_utils.py
index 2895bde0..8deaefd0 100644
--- a/src/codemodder/codemods/test/integration_utils.py
+++ b/src/codemodder/codemods/test/integration_utils.py
@@ -6,6 +6,7 @@
 from types import ModuleType
 
 import git
+import jsonschema
 
 from codemodder import __version__, registry
 
@@ -99,7 +100,8 @@ def _assert_results_fields(self, results, output_path):
         result = results[0]
         assert result["codemod"] == self.codemod_instance.id
         assert result["references"] == [
-            ref.to_json() for ref in self.codemod_instance.references
+            ref.model_dump(exclude_none=True)
+            for ref in self.codemod_instance.references
         ]
 
         # TODO: once we add description for each url.
@@ -118,15 +120,15 @@ def _assert_results_fields(self, results, output_path):
 
         assert len(change["changes"]) == self.num_changes
         line_change = change["changes"][0]
-        assert line_change["lineNumber"] == str(self.expected_line_change)
+        assert line_change["lineNumber"] == int(self.expected_line_change)
         assert line_change["description"] == self.change_description
-        assert line_change["packageActions"] == []
-        assert line_change["properties"] == {}
 
-    def _assert_codetf_output(self):
+    def _assert_codetf_output(self, codetf_schema):
         with open(self.output_path, "r", encoding="utf-8") as f:
             codetf = json.load(f)
 
+        jsonschema.validate(codetf, codetf_schema)
+
         assert sorted(codetf.keys()) == ["results", "run"]
         run = codetf["run"]
         self._assert_run_fields(run, self.output_path)
@@ -149,7 +151,7 @@ def check_code_after(self) -> ModuleType:
             path=self.code_path, allowed_exceptions=self.allowed_exceptions
         )
 
-    def test_file_rewritten(self):
+    def test_file_rewritten(self, codetf_schema):
         """
         Tests that file is re-written correctly with new code and correct codetf output.
 
@@ -183,7 +185,7 @@ def test_file_rewritten(self):
 
         self.check_code_after()
         self.check_dependencies_after()
-        self._assert_codetf_output()
+        self._assert_codetf_output(codetf_schema)
         pathlib.Path(self.output_path).unlink(missing_ok=True)
         self._run_idempotency_chec(command)
 
diff --git a/src/codemodder/codetf.py b/src/codemodder/codetf.py
new file mode 100644
index 00000000..ce9eb327
--- /dev/null
+++ b/src/codemodder/codetf.py
@@ -0,0 +1,137 @@
+"""
+Data models for the CodeTF format.
+
+We need to keep this in sync with the CodeTF schema.
+"""
+
+from __future__ import annotations
+
+import os
+import sys
+from enum import Enum
+from typing import TYPE_CHECKING, Optional
+
+from pydantic import BaseModel, model_validator
+
+from codemodder import __version__
+from codemodder.logging import logger
+
+if TYPE_CHECKING:
+    from codemodder.context import CodemodExecutionContext
+
+
+class Action(Enum):
+    ADD = "add"
+    REMOVE = "remove"
+
+
+class PackageResult(Enum):
+    COMPLETED = "completed"
+    FAILED = "failed"
+    SKIPPED = "skipped"
+
+
+class DiffSide(Enum):
+    LEFT = "left"
+    RIGHT = "right"
+
+
+class PackageAction(BaseModel):
+    action: Action
+    result: PackageResult
+    package: str
+
+
+class Change(BaseModel):
+    lineNumber: int
+    description: Optional[str]
+    # All of our changes are currently treated as additive, so it makes sense
+    # for the comments to appear on the RIGHT side of the split diff. Eventually we
+    # may want to differentiate between LEFT and RIGHT, but for now we'll just
+    # default to RIGHT.
+    diffSide: DiffSide = DiffSide.RIGHT
+    properties: Optional[dict] = None
+    packageActions: Optional[list[PackageAction]] = None
+
+
+class ChangeSet(BaseModel):
+    """A set of changes made to a file at `path`"""
+
+    path: str
+    diff: str
+    changes: list[Change] = []
+
+
+class Reference(BaseModel):
+    url: str
+    description: Optional[str] = None
+
+    @model_validator(mode="after")
+    def validate_description(self):
+        self.description = self.description or self.url
+        return self
+
+
+class Result(BaseModel):
+    codemod: str
+    summary: str
+    description: str
+    references: Optional[list[Reference]] = None
+    properties: Optional[dict] = None
+    failedFiles: Optional[list[str]] = None
+    changeset: list[ChangeSet]
+
+
+class Sarif(BaseModel):
+    artifact: str
+    sha1: str
+
+
+class Run(BaseModel):
+    vendor: str
+    tool: str
+    version: str
+    projectName: Optional[str] = None
+    commandLine: str
+    elapsed: Optional[int]
+    directory: str
+    sarifs: list[Sarif] = []
+
+
+class CodeTF(BaseModel):
+    run: Run
+    results: list[Result]
+
+    @classmethod
+    def build(
+        cls,
+        context: CodemodExecutionContext,
+        elapsed_ms,
+        original_args,
+        results: list[Result],
+    ):
+        command_name = os.path.basename(sys.argv[0])
+        command_args = " ".join(original_args)
+        run = Run(
+            vendor="pixee",
+            tool="codemodder-python",
+            version=__version__,
+            projectName=None,
+            commandLine=f"{command_name} {command_args}",
+            elapsed=elapsed_ms,
+            directory=str(context.directory.absolute()),
+            # TODO: this should be populated from the context
+            sarifs=[],
+        )
+        return cls(run=run, results=results)
+
+    def write_report(self, outfile):
+        try:
+            with open(outfile, "w", encoding="utf-8") as f:
+                f.write(self.model_dump_json(exclude_none=True))
+        except Exception:
+            logger.exception("failed to write report file.")
+            # Any issues with writing the output file should exit status 2.
+            return 2
+        logger.debug("wrote report to %s", outfile)
+        return 0
diff --git a/src/codemodder/context.py b/src/codemodder/context.py
index 461b4b7a..4824d29a 100644
--- a/src/codemodder/context.py
+++ b/src/codemodder/context.py
@@ -6,7 +6,8 @@
 from textwrap import indent
 from typing import TYPE_CHECKING, Iterator, List
 
-from codemodder.change import ChangeSet
+from codemodder.codetf import ChangeSet
+from codemodder.codetf import Result as CodeTFResult
 from codemodder.dependency import (
     Dependency,
     build_dependency_notification,
@@ -150,22 +151,20 @@ def process_results(self, codemod_id: str, results: Iterator[FileContext]):
             self.add_dependencies(codemod_id, file_context.dependencies)
             self.timer.aggregate(file_context.timer)
 
-    def compile_results(self, codemods: list[BaseCodemod]):
+    def compile_results(self, codemods: list[BaseCodemod]) -> list[CodeTFResult]:
         results = []
         for codemod in codemods:
-            data = {
-                "codemod": codemod.id,
-                "summary": codemod.summary,
-                "description": self.add_description(codemod),
-                "references": [ref.to_json() for ref in codemod.references],
-                "properties": {},
-                "failedFiles": [str(file) for file in self.get_failures(codemod.id)],
-                "changeset": [
-                    change.to_json() for change in self.get_results(codemod.id)
-                ],
-            }
-
-            results.append(data)
+            result = CodeTFResult(
+                codemod=codemod.id,
+                summary=codemod.summary,
+                description=self.add_description(codemod),
+                references=codemod.references,
+                properties={},
+                failedFiles=[str(file) for file in self.get_failures(codemod.id)],
+                changeset=self.get_results(codemod.id),
+            )
+
+            results.append(result)
 
         return results
 
diff --git a/src/codemodder/dependency_management/base_dependency_writer.py b/src/codemodder/dependency_management/base_dependency_writer.py
index c9be50e2..8d1931a5 100644
--- a/src/codemodder/dependency_management/base_dependency_writer.py
+++ b/src/codemodder/dependency_management/base_dependency_writer.py
@@ -4,7 +4,7 @@
 
 from packaging.requirements import Requirement
 
-from codemodder.change import Action, Change, ChangeSet, PackageAction, Result
+from codemodder.codetf import Action, Change, ChangeSet, PackageAction, PackageResult
 from codemodder.dependency import Dependency
 from codemodder.project_analysis.file_parsers.package_store import PackageStore
 
@@ -61,7 +61,11 @@ def build_changes(
                     "contextual_description_position": "right",
                 },
                 packageActions=[
-                    PackageAction(Action.ADD, Result.COMPLETED, str(dep.requirement))
+                    PackageAction(
+                        action=Action.ADD,
+                        result=PackageResult.COMPLETED,
+                        package=str(dep.requirement),
+                    )
                 ],
             )
             for i, dep in enumerate(dependencies)
diff --git a/src/codemodder/dependency_management/dependency_manager.py b/src/codemodder/dependency_management/dependency_manager.py
index 3e6f2b71..4fe777b8 100644
--- a/src/codemodder/dependency_management/dependency_manager.py
+++ b/src/codemodder/dependency_management/dependency_manager.py
@@ -1,7 +1,7 @@
 from pathlib import Path
 from typing import Optional
 
-from codemodder.change import ChangeSet
+from codemodder.codetf import ChangeSet
 from codemodder.dependency import Dependency
 from codemodder.dependency_management.pyproject_writer import PyprojectWriter
 from codemodder.dependency_management.requirements_txt_writer import (
diff --git a/src/codemodder/dependency_management/pyproject_writer.py b/src/codemodder/dependency_management/pyproject_writer.py
index 28441525..f7c767b2 100644
--- a/src/codemodder/dependency_management/pyproject_writer.py
+++ b/src/codemodder/dependency_management/pyproject_writer.py
@@ -3,7 +3,7 @@
 
 import tomlkit
 
-from codemodder.change import ChangeSet
+from codemodder.codetf import ChangeSet
 from codemodder.dependency import Dependency
 from codemodder.dependency_management.base_dependency_writer import DependencyWriter
 from codemodder.diff import create_diff_and_linenums
@@ -41,8 +41,8 @@ def add_to_file(
             dependencies, added_line_nums_strategy, added_line_nums
         )
         return ChangeSet(
-            str(self.path.relative_to(self.parent_directory)),
-            diff,
+            path=str(self.path.relative_to(self.parent_directory)),
+            diff=diff,
             changes=changes,
         )
 
diff --git a/src/codemodder/dependency_management/requirements_txt_writer.py b/src/codemodder/dependency_management/requirements_txt_writer.py
index 5661d204..646bdd93 100644
--- a/src/codemodder/dependency_management/requirements_txt_writer.py
+++ b/src/codemodder/dependency_management/requirements_txt_writer.py
@@ -1,6 +1,6 @@
 from typing import Optional
 
-from codemodder.change import ChangeSet
+from codemodder.codetf import ChangeSet
 from codemodder.dependency import Dependency
 from codemodder.dependency_management.base_dependency_writer import DependencyWriter
 from codemodder.diff import create_diff
@@ -40,8 +40,8 @@ def add_to_file(
             dependencies, original_lines_strategy, original_lines
         )
         return ChangeSet(
-            str(self.path.relative_to(self.parent_directory)),
-            diff,
+            path=str(self.path.relative_to(self.parent_directory)),
+            diff=diff,
             changes=changes,
         )
 
diff --git a/src/codemodder/dependency_management/setup_py_writer.py b/src/codemodder/dependency_management/setup_py_writer.py
index 23689935..f9d07920 100644
--- a/src/codemodder/dependency_management/setup_py_writer.py
+++ b/src/codemodder/dependency_management/setup_py_writer.py
@@ -5,10 +5,10 @@
 from libcst.codemod import CodemodContext
 from packaging.requirements import Requirement
 
-from codemodder.change import ChangeSet
 from codemodder.codemods.api import Metadata, ReviewGuidance, SimpleCodemod
 from codemodder.codemods.utils import is_setup_py_file
 from codemodder.codemods.utils_mixin import NameResolutionMixin
+from codemodder.codetf import ChangeSet
 from codemodder.dependency import Dependency
 from codemodder.dependency_management.base_dependency_writer import DependencyWriter
 from codemodder.diff import create_diff_from_tree
@@ -48,8 +48,8 @@ def add_to_file(
             dependencies, fixed_line_number_strategy, codemod.line_num_changed
         )
         return ChangeSet(
-            str(self.path.relative_to(self.parent_directory)),
-            diff,
+            path=str(self.path.relative_to(self.parent_directory)),
+            diff=diff,
             changes=changes,
         )
 
diff --git a/src/codemodder/dependency_management/setupcfg_writer.py b/src/codemodder/dependency_management/setupcfg_writer.py
index 34613212..6d02083a 100644
--- a/src/codemodder/dependency_management/setupcfg_writer.py
+++ b/src/codemodder/dependency_management/setupcfg_writer.py
@@ -2,7 +2,7 @@
 import re
 from typing import Optional
 
-from codemodder.change import ChangeSet
+from codemodder.codetf import ChangeSet
 from codemodder.dependency import Dependency
 from codemodder.dependency_management.base_dependency_writer import DependencyWriter
 from codemodder.diff import create_diff_and_linenums
@@ -61,8 +61,8 @@ def add_to_file(
             dependencies, added_line_nums_strategy, added_line_nums
         )
         return ChangeSet(
-            str(self.path.relative_to(self.parent_directory)),
-            diff,
+            path=str(self.path.relative_to(self.parent_directory)),
+            diff=diff,
             changes=changes,
         )
 
diff --git a/src/codemodder/file_context.py b/src/codemodder/file_context.py
index 2b70de1b..a0aceea8 100644
--- a/src/codemodder/file_context.py
+++ b/src/codemodder/file_context.py
@@ -1,7 +1,7 @@
 from dataclasses import dataclass, field
 from pathlib import Path
 
-from codemodder.change import Change, ChangeSet
+from codemodder.codetf import Change, ChangeSet
 from codemodder.dependency import Dependency
 from codemodder.result import Result
 from codemodder.utils.timer import Timer
diff --git a/src/codemodder/report/__init__.py b/src/codemodder/report/__init__.py
deleted file mode 100644
index e69de29b..00000000
diff --git a/src/codemodder/report/codetf_reporter.py b/src/codemodder/report/codetf_reporter.py
deleted file mode 100644
index 5ee15e5e..00000000
--- a/src/codemodder/report/codetf_reporter.py
+++ /dev/null
@@ -1,51 +0,0 @@
-import json
-from os.path import abspath
-
-from codemodder import __version__
-from codemodder.logging import logger
-
-
-def base_report():
-    return {
-        "run": {
-            "vendor": "pixee",
-            "tool": "codemodder-python",
-            "version": __version__,
-            "sarifs": [],
-        },
-        "results": [],
-    }
-
-
-def report_default(elapsed_ms, parsed_args, original_args, results_by_codemod):
-    report = CodeTF()
-    absolute_path = abspath(parsed_args.directory)
-    report.generate(elapsed_ms, original_args, absolute_path, results_by_codemod)
-    report.write_report(parsed_args.output)
-
-
-class CodeTF:
-    def __init__(self):
-        self.report = base_report()
-
-    def generate(self, elapsed_ms, original_args, absolute_path, results_by_codemod):
-        self.report["run"]["elapsed"] = str(elapsed_ms)
-        # TODO: this shouldn't be necessary, we should just use sys.argv
-        # I think this is an artifact of using python -m codemodder, which is being deprecated
-        self.report["run"]["commandLine"] = self._recreate_command(original_args)
-        self.report["run"]["directory"] = absolute_path
-        self.report["results"] = results_by_codemod
-
-    def _recreate_command(self, original_args):
-        return f"codemodder {' '.join(original_args)}"
-
-    def write_report(self, outfile):
-        try:
-            with open(outfile, "w", encoding="utf-8") as f:
-                json.dump(self.report, f)
-        except Exception:
-            logger.exception("failed to write report file.")
-            # Any issues with writing the output file should exit status 2.
-            return 2
-        logger.debug("wrote report to %s", outfile)
-        return 0
diff --git a/src/core_codemods/file_resource_leak.py b/src/core_codemods/file_resource_leak.py
index c55591d6..bc8a8d97 100644
--- a/src/core_codemods/file_resource_leak.py
+++ b/src/core_codemods/file_resource_leak.py
@@ -11,7 +11,6 @@
     ScopeProvider,
 )
 
-from codemodder.change import Change
 from codemodder.codemods.libcst_transformer import (
     LibcstResultTransformer,
     LibcstTransformerPipeline,
@@ -22,6 +21,7 @@
     NameAndAncestorResolutionMixin,
     NameResolutionMixin,
 )
+from codemodder.codetf import Change
 from codemodder.file_context import FileContext
 from codemodder.result import Result
 from core_codemods.api import Metadata, Reference, ReviewGuidance
@@ -222,7 +222,10 @@ def _handle_block(
             if self._is_fixable(original_block, index, named_targets, other_targets):
                 line_number = self.get_metadata(PositionProvider, resource).start.line
                 self.changes.append(
-                    Change(line_number, FileResourceLeakTransformer.change_description)
+                    Change(
+                        lineNumber=line_number,
+                        description=FileResourceLeakTransformer.change_description,
+                    )
                 )
 
                 # grab the index of the last statement with reference to the resource
diff --git a/src/core_codemods/fix_assert_tuple.py b/src/core_codemods/fix_assert_tuple.py
index 2a054078..8dce30bb 100644
--- a/src/core_codemods/fix_assert_tuple.py
+++ b/src/core_codemods/fix_assert_tuple.py
@@ -2,12 +2,12 @@
 
 import libcst as cst
 
-from codemodder.change import Change
 from codemodder.codemods.libcst_transformer import (
     LibcstResultTransformer,
     LibcstTransformerPipeline,
 )
 from codemodder.codemods.utils_mixin import NameResolutionMixin
+from codemodder.codetf import Change
 from core_codemods.api import Metadata, ReviewGuidance
 from core_codemods.api.core_codemod import CoreCodemod
 
diff --git a/src/core_codemods/order_imports.py b/src/core_codemods/order_imports.py
index f26d7c2f..91aae686 100644
--- a/src/core_codemods/order_imports.py
+++ b/src/core_codemods/order_imports.py
@@ -1,7 +1,6 @@
 import libcst as cst
 from libcst.metadata import PositionProvider
 
-from codemodder.change import Change
 from codemodder.codemods.transformations.clean_imports import (
     GatherTopLevelImportBlocks,
     OrderImportsBlocksTransform,
@@ -41,11 +40,9 @@ def transform_module_impl(self, tree: cst.Module) -> cst.Module:
             # seemingly redundant, this check makes it possible to return the original tree
             for i, changed in enumerate(order_transformer.changes):
                 if changed:
-                    line_number = self.node_position(
-                        top_imports_visitor.top_imports_blocks[i][0]
-                    ).start.line
-                    self.file_context.codemod_changes.append(
-                        Change(line_number, self.change_description)
+                    self.add_change(
+                        top_imports_visitor.top_imports_blocks[i][0],
+                        self.change_description,
                     )
             return result_tree
         return tree
diff --git a/src/core_codemods/remove_unused_imports.py b/src/core_codemods/remove_unused_imports.py
index 67c8ec95..62deac9e 100644
--- a/src/core_codemods/remove_unused_imports.py
+++ b/src/core_codemods/remove_unused_imports.py
@@ -7,7 +7,6 @@
     ScopeProvider,
 )
 
-from codemodder.change import Change
 from codemodder.codemods.check_annotations import is_disabled_by_annotations
 from codemodder.codemods.transformations.remove_unused_imports import (
     RemoveUnusedImportsTransformer,
@@ -48,9 +47,7 @@ def transform_module_impl(self, tree: cst.Module) -> cst.Module:
                     self.metadata,  # type: ignore
                     messages=self.IGNORE_ANNOTATIONS,
                 ):
-                    self.file_context.codemod_changes.append(
-                        Change(pos.start.line, self.change_description)
-                    )
+                    self.add_change_from_position(pos, self.change_description)
                     filtered_unused_imports.add((import_alias, importt))
         return tree.visit(RemoveUnusedImportsTransformer(filtered_unused_imports))
 
diff --git a/src/core_codemods/secure_flask_session_config.py b/src/core_codemods/secure_flask_session_config.py
index 46b78285..fea58347 100644
--- a/src/core_codemods/secure_flask_session_config.py
+++ b/src/core_codemods/secure_flask_session_config.py
@@ -3,9 +3,9 @@
 from libcst.codemod import Codemod, CodemodContext
 from libcst.metadata import ParentNodeProvider
 
-from codemodder.change import Change
 from codemodder.codemods.base_visitor import BaseTransformer
 from codemodder.codemods.utils_mixin import NameResolutionMixin
+from codemodder.codetf import Change
 from codemodder.file_context import FileContext
 from codemodder.utils.utils import extract_targets_of_assignment, true_value
 from core_codemods.api import Metadata, Reference, ReviewGuidance, SimpleCodemod
@@ -194,5 +194,8 @@ def _is_config_subscript(self, original_node: cst.Assign):
     def report_change(self, original_node):
         line_number = self.lineno_for_node(original_node)
         self.file_context.codemod_changes.append(
-            Change(line_number, SecureFlaskSessionConfig.change_description)
+            Change(
+                lineNumber=line_number,
+                description=SecureFlaskSessionConfig.change_description,
+            )
         )
diff --git a/src/core_codemods/sql_parameterization.py b/src/core_codemods/sql_parameterization.py
index 401df5b9..7e39c9ac 100644
--- a/src/core_codemods/sql_parameterization.py
+++ b/src/core_codemods/sql_parameterization.py
@@ -13,7 +13,6 @@
     ScopeProvider,
 )
 
-from codemodder.change import Change
 from codemodder.codemods.base_visitor import UtilsMixin
 from codemodder.codemods.libcst_transformer import (
     LibcstResultTransformer,
@@ -30,6 +29,7 @@
     infer_expression_type,
 )
 from codemodder.codemods.utils_mixin import NameAndAncestorResolutionMixin
+from codemodder.codetf import Change
 from core_codemods.api import Metadata, Reference, ReviewGuidance
 from core_codemods.api.core_codemod import CoreCodemod
 
@@ -149,8 +149,8 @@ def transform_module_impl(self, tree: cst.Module) -> cst.Module:
                 line_number = self.get_metadata(PositionProvider, call).start.line
                 self.file_context.codemod_changes.append(
                     Change(
-                        line_number,
-                        SQLQueryParameterizationTransformer.change_description,
+                        lineNumber=line_number,
+                        description=SQLQueryParameterizationTransformer.change_description,
                     )
                 )
                 # Normalization and cleanup
diff --git a/src/core_codemods/url_sandbox.py b/src/core_codemods/url_sandbox.py
index 3ac72d94..40ebb3f5 100644
--- a/src/core_codemods/url_sandbox.py
+++ b/src/core_codemods/url_sandbox.py
@@ -6,12 +6,12 @@
 from libcst.codemod.visitors import AddImportsVisitor, ImportItem
 from libcst.metadata import PositionProvider, ScopeProvider
 
-from codemodder.change import Change
 from codemodder.codemods.base_visitor import UtilsMixin
 from codemodder.codemods.transformations.remove_unused_imports import (
     RemoveUnusedImportsCodemod,
 )
 from codemodder.codemods.utils import ReplaceNodes
+from codemodder.codetf import Change
 from codemodder.dependency import Security
 from codemodder.file_context import FileContext
 from core_codemods.api import Metadata, Reference, ReviewGuidance, SimpleCodemod
@@ -137,7 +137,10 @@ def leave_Call(self, original_node: cst.Call):
                             }
                         )
                         self.changes_in_file.append(
-                            Change(line_number, UrlSandbox.change_description)
+                            Change(
+                                lineNumber=line_number,
+                                description=UrlSandbox.change_description,
+                            )
                         )
 
             # case req.get(...)
@@ -151,7 +154,10 @@ def leave_Call(self, original_node: cst.Call):
                     }
                 )
                 self.changes_in_file.append(
-                    Change(line_number, UrlSandbox.change_description)
+                    Change(
+                        lineNumber=line_number,
+                        description=UrlSandbox.change_description,
+                    )
                 )
 
     def _find_assignments(self, node: CSTNode):
diff --git a/tests/conftest.py b/tests/conftest.py
index ecaeb400..c8d55daa 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -6,7 +6,7 @@ def disable_write_report(mocker):
     """
     Unit tests should not write analysis report or update any source files.
     """
-    mocker.patch("codemodder.report.codetf_reporter.CodeTF.write_report")
+    mocker.patch("codemodder.codetf.CodeTF.write_report")
 
 
 @pytest.fixture(autouse=True)
@@ -31,7 +31,8 @@ def disable_write_dependencies(mocker):
     Unit tests should not write any dependency files
     """
     mocker.patch(
-        "codemodder.dependency_management.dependency_manager.DependencyManager.write"
+        "codemodder.dependency_management.dependency_manager.DependencyManager.write",
+        return_value=None,
     )
 
 
diff --git a/tests/dependency_management/test_base_dependency_writer.py b/tests/dependency_management/test_base_dependency_writer.py
index 06f433d1..58ce858f 100644
--- a/tests/dependency_management/test_base_dependency_writer.py
+++ b/tests/dependency_management/test_base_dependency_writer.py
@@ -1,4 +1,4 @@
-from codemodder.change import ChangeSet
+from codemodder.codetf import ChangeSet
 from codemodder.dependency import Dependency, Requirement
 from codemodder.dependency_management.base_dependency_writer import DependencyWriter
 from codemodder.project_analysis.file_parsers.package_store import PackageStore
diff --git a/tests/dependency_management/test_dependency_manager.py b/tests/dependency_management/test_dependency_manager.py
index fee20f61..84ec44e0 100644
--- a/tests/dependency_management/test_dependency_manager.py
+++ b/tests/dependency_management/test_dependency_manager.py
@@ -1,6 +1,6 @@
 import pytest
 
-from codemodder.change import ChangeSet
+from codemodder.codetf import ChangeSet
 from codemodder.dependency import DefusedXML, Security
 from codemodder.dependency_management import DependencyManager
 from codemodder.project_analysis.file_parsers import (
diff --git a/tests/dependency_management/test_pyproject_writer.py b/tests/dependency_management/test_pyproject_writer.py
index b806f2c9..06c19add 100644
--- a/tests/dependency_management/test_pyproject_writer.py
+++ b/tests/dependency_management/test_pyproject_writer.py
@@ -2,7 +2,7 @@
 
 import pytest
 
-from codemodder.change import DiffSide
+from codemodder.codetf import DiffSide
 from codemodder.dependency import DefusedXML, Security
 from codemodder.dependency_management.pyproject_writer import PyprojectWriter
 from codemodder.project_analysis.file_parsers.package_store import (
diff --git a/tests/dependency_management/test_requirements_txt_writer.py b/tests/dependency_management/test_requirements_txt_writer.py
index db1ce993..dd7c68bc 100644
--- a/tests/dependency_management/test_requirements_txt_writer.py
+++ b/tests/dependency_management/test_requirements_txt_writer.py
@@ -2,7 +2,7 @@
 
 import pytest
 
-from codemodder.change import DiffSide
+from codemodder.codetf import DiffSide
 from codemodder.dependency import DefusedXML, Requirement, Security
 from codemodder.dependency_management.requirements_txt_writer import (
     RequirementsTxtWriter,
diff --git a/tests/dependency_management/test_setup_py_writer.py b/tests/dependency_management/test_setup_py_writer.py
index a82f0096..d7c06f13 100644
--- a/tests/dependency_management/test_setup_py_writer.py
+++ b/tests/dependency_management/test_setup_py_writer.py
@@ -2,7 +2,7 @@
 
 import pytest
 
-from codemodder.change import DiffSide
+from codemodder.codetf import DiffSide
 from codemodder.dependency import DefusedXML, Security
 from codemodder.dependency_management.setup_py_writer import SetupPyWriter
 from codemodder.project_analysis.file_parsers.package_store import (
diff --git a/tests/dependency_management/test_setupcfgt_writer.py b/tests/dependency_management/test_setupcfgt_writer.py
index 7c037980..e4c68227 100644
--- a/tests/dependency_management/test_setupcfgt_writer.py
+++ b/tests/dependency_management/test_setupcfgt_writer.py
@@ -3,7 +3,7 @@
 import mock
 import pytest
 
-from codemodder.change import DiffSide
+from codemodder.codetf import DiffSide
 from codemodder.dependency import DefusedXML, Security
 from codemodder.dependency_management.setupcfg_writer import SetupCfgWriter
 from codemodder.project_analysis.file_parsers.package_store import (
diff --git a/tests/report/__init__.py b/tests/report/__init__.py
deleted file mode 100644
index e69de29b..00000000
diff --git a/tests/report/test_codetf_reporter.py b/tests/report/test_codetf_reporter.py
deleted file mode 100644
index e128f486..00000000
--- a/tests/report/test_codetf_reporter.py
+++ /dev/null
@@ -1,31 +0,0 @@
-import json
-
-import mock
-import pytest
-
-from codemodder.report.codetf_reporter import CodeTF
-
-
-@pytest.fixture(autouse=True, scope="module")
-def disable_write_report():
-    """Disable write_report mocking so it can be properlly tested"""
-    patch_open = mock.patch("builtins.open")
-    patch_open.start()
-    yield
-    patch_open.stop()
-
-
-class TestCodeTfReporter:
-    @mock.patch("json.dump")
-    def test_write_report(self, mock_dump):
-        reporter = CodeTF()
-        res = reporter.write_report("any/file")
-        assert res == 0
-        mock_dump.assert_called()
-
-    @mock.patch("json.dump", side_effect=json.JSONDecodeError)
-    def test_write_report_fails(self, mock_dump):
-        reporter = CodeTF()
-        res = reporter.write_report("any/file")
-        assert res == 2
-        mock_dump.assert_called()
diff --git a/tests/test_change.py b/tests/test_change.py
deleted file mode 100644
index a1729e8b..00000000
--- a/tests/test_change.py
+++ /dev/null
@@ -1,39 +0,0 @@
-import pytest
-
-from codemodder.change import Change, ChangeSet, DiffSide
-
-
-def test_change():
-    diff = "--- a/test\n+++ b/test\n@@ -1,1 +1,1 @@\n-1\n+2\n"
-    changeset = ChangeSet(
-        path="test",
-        diff=diff,
-        changes=[
-            Change(
-                lineNumber=1,
-                description="Change 1 to 2",
-            ),
-        ],
-    )
-
-    result = changeset.to_json()
-
-    assert result["path"] == "test"
-    assert result["diff"] == diff
-    assert result["changes"][0]["lineNumber"] == str(1)
-    assert result["changes"][0]["description"] == "Change 1 to 2"
-    assert result["changes"][0]["diffSide"] == "right"
-    assert result["changes"][0]["properties"] == {}
-    assert result["changes"][0]["packageActions"] == []
-
-
-@pytest.mark.parametrize("side", [DiffSide.LEFT, DiffSide.RIGHT])
-def test_change_diffside(side):
-    change = Change(
-        lineNumber=1,
-        description="Change 1 to 2",
-        diffSide=side,
-    )
-
-    assert change.diffSide == side
-    assert change.to_json()["diffSide"] == side.value
diff --git a/tests/test_codemodder.py b/tests/test_codemodder.py
index a2fc56dc..7e3236ac 100644
--- a/tests/test_codemodder.py
+++ b/tests/test_codemodder.py
@@ -35,8 +35,8 @@ def test_no_files_matched(self, mock_parse, tmpdir):
         assert codetf.exists()
 
     @mock.patch("libcst.parse_module", side_effect=Exception)
-    @mock.patch("codemodder.codemodder.report_default")
-    def test_cst_parsing_fails(self, mock_reporting, mock_parse):
+    @mock.patch("codemodder.codetf.CodeTF.build")
+    def test_cst_parsing_fails(self, build_report, mock_parse):
         args = [
             "tests/samples/",
             "--output",
@@ -52,19 +52,21 @@ def test_cst_parsing_fails(self, mock_reporting, mock_parse):
         assert res == 0
         mock_parse.assert_called()
 
-        mock_reporting.assert_called_once()
-        args_to_reporting = mock_reporting.call_args_list[0][0]
+        build_report.assert_called_once()
+        args_to_reporting = build_report.call_args_list[0][0]
         assert len(args_to_reporting) == 4
         _, _, _, results_by_codemod = args_to_reporting
         assert results_by_codemod != []
 
         requests_report = results_by_codemod[0]
-        assert requests_report["changeset"] == []
-        assert len(requests_report["failedFiles"]) == 1
-        assert sorted(requests_report["failedFiles"]) == [
+        assert requests_report.changeset == []
+        assert len(requests_report.failedFiles) == 1
+        assert sorted(requests_report.failedFiles) == [
             "tests/samples/unverified_request.py",
         ]
 
+        build_report.return_value.write_report.assert_called_once()
+
     @mock.patch("codemodder.codemods.libcst_transformer.update_code")
     @mock.patch("codemodder.codemods.semgrep.semgrep_run", side_effect=semgrep_run)
     def test_dry_run(self, _, mock_update_code, tmpdir):
@@ -87,7 +89,7 @@ def test_dry_run(self, _, mock_update_code, tmpdir):
         mock_update_code.assert_not_called()
 
     @pytest.mark.parametrize("dry_run", [True, False])
-    @mock.patch("codemodder.codemodder.report_default")
+    @mock.patch("codemodder.codetf.CodeTF.build")
     def test_reporting(self, mock_reporting, dry_run):
         args = [
             "tests/samples/",
@@ -109,6 +111,8 @@ def test_reporting(self, mock_reporting, dry_run):
 
         assert len(results_by_codemod) == 3
 
+        mock_reporting.return_value.write_report.assert_called_once()
+
     @mock.patch("codemodder.codemods.semgrep.semgrep_run")
     def test_no_codemods_to_run(self, mock_semgrep_run, tmpdir):
         codetf = tmpdir / "result.codetf"
@@ -130,11 +134,9 @@ def test_no_codemods_to_run(self, mock_semgrep_run, tmpdir):
 
     @pytest.mark.parametrize("codemod", ["secure-random", "pixee:python/secure-random"])
     @mock.patch("codemodder.context.CodemodExecutionContext.compile_results")
-    @mock.patch("codemodder.codemodder.report_default")
-    def test_run_codemod_name_or_id(
-        self, report_default, mock_compile_results, codemod
-    ):
-        del report_default
+    @mock.patch("codemodder.codetf.CodeTF.write_report")
+    def test_run_codemod_name_or_id(self, write_report, mock_compile_results, codemod):
+        del write_report
         args = [
             "tests/samples/",
             "--output",
@@ -148,7 +150,7 @@ def test_run_codemod_name_or_id(
 
 
 class TestExitCode:
-    @mock.patch("codemodder.codemodder.report_default")
+    @mock.patch("codemodder.codetf.CodeTF.write_report")
     def test_success_0(self, mock_report):
         del mock_report
         args = [
@@ -163,7 +165,7 @@ def test_success_0(self, mock_report):
         exit_code = run(args)
         assert exit_code == 0
 
-    @mock.patch("codemodder.codemodder.report_default")
+    @mock.patch("codemodder.codetf.CodeTF.write_report")
     def test_bad_project_dir_1(self, mock_report):
         del mock_report
         args = [
@@ -176,7 +178,7 @@ def test_bad_project_dir_1(self, mock_report):
         exit_code = run(args)
         assert exit_code == 1
 
-    @mock.patch("codemodder.codemodder.report_default")
+    @mock.patch("codemodder.codetf.CodeTF.write_report")
     def test_conflicting_include_exclude(self, mock_report):
         del mock_report
         args = [
@@ -192,7 +194,7 @@ def test_conflicting_include_exclude(self, mock_report):
             run(args)
         assert err.value.args[0] == 3
 
-    @mock.patch("codemodder.codemodder.report_default")
+    @mock.patch("codemodder.codetf.CodeTF.write_report")
     def test_bad_codemod_name(self, mock_report):
         del mock_report
         bad_codemod = "doesntexist"
diff --git a/tests/test_codetf.py b/tests/test_codetf.py
new file mode 100644
index 00000000..7f2acc5f
--- /dev/null
+++ b/tests/test_codetf.py
@@ -0,0 +1,113 @@
+import json
+from pathlib import Path
+
+import jsonschema
+import pytest
+import requests
+
+from codemodder.codetf import Change, ChangeSet, CodeTF, DiffSide, Result
+
+
+@pytest.fixture(autouse=True)
+def disable_write_report():
+    """
+    Override conftest to enable results to be written to disk for these tests.
+    """
+
+
+@pytest.fixture(autouse=True, scope="module")
+def codetf_schema():
+    schema_path = "https://raw.githubusercontent.com/pixee/codemodder-specs/main/codetf.schema.json"
+    response = requests.get(schema_path)
+    yield json.loads(response.text)
+
+
+def test_change():
+    diff = "--- a/test\n+++ b/test\n@@ -1,1 +1,1 @@\n-1\n+2\n"
+    changeset = ChangeSet(
+        path="test",
+        diff=diff,
+        changes=[
+            Change(
+                lineNumber=1,
+                description="Change 1 to 2",
+            ),
+        ],
+    )
+
+    result = changeset.model_dump()
+
+    assert result["path"] == "test"
+    assert result["diff"] == diff
+    assert result["changes"][0]["lineNumber"] == 1
+    assert result["changes"][0]["description"] == "Change 1 to 2"
+    assert result["changes"][0]["diffSide"] == DiffSide.RIGHT
+    assert result["changes"][0]["properties"] is None
+    assert result["changes"][0]["packageActions"] is None
+
+
+@pytest.mark.parametrize("side", [DiffSide.LEFT, DiffSide.RIGHT])
+def test_change_diffside(side):
+    change = Change(
+        lineNumber=1,
+        description="Change 1 to 2",
+        diffSide=side,
+    )
+
+    assert change.diffSide == side
+    assert change.model_dump()["diffSide"] == side
+
+
+def test_write_codetf(tmpdir, mocker, codetf_schema):
+    path = tmpdir / "test.codetf.json"
+
+    assert not path.exists()
+
+    context = mocker.MagicMock(directory=Path("/foo/bar/whatever"))
+    codetf = CodeTF.build(context, 42, [], [])
+    retval = codetf.write_report(path)
+
+    assert retval == 0
+    assert path.exists()
+
+    data = path.read_text(encoding="utf-8")
+    CodeTF.model_validate_json(data)
+
+    jsonschema.validate(json.loads(data), codetf_schema)
+
+
+def test_write_codetf_with_results(tmpdir, mocker, codetf_schema):
+    path = tmpdir / "test.codetf.json"
+
+    assert not path.exists()
+
+    context = mocker.MagicMock(directory=Path("/foo/bar/whatever"))
+    results = [
+        Result(
+            codemod="test",
+            summary="test",
+            description="test",
+            changeset=[
+                ChangeSet(
+                    path="test",
+                    diff="--- a/test\n+++ b/test\n@@ -1,1 +1,1 @@\n-1\n+2\n",
+                    changes=[
+                        Change(
+                            lineNumber=1,
+                            description="Change 1 to 2",
+                        ),
+                    ],
+                ),
+            ],
+        )
+    ]
+    codetf = CodeTF.build(context, 42, [], results)
+    retval = codetf.write_report(path)
+
+    assert retval == 0
+    assert path.exists()
+
+    data = path.read_text(encoding="utf-8")
+    CodeTF.model_validate_json(data)
+
+    jsonschema.validate(json.loads(data), codetf_schema)
diff --git a/tests/test_context.py b/tests/test_context.py
index 59135dd0..2238afb8 100644
--- a/tests/test_context.py
+++ b/tests/test_context.py
@@ -1,9 +1,23 @@
+import pytest
+
 from codemodder.context import CodemodExecutionContext as Context
 from codemodder.dependency import Security
 from codemodder.project_analysis.python_repo_manager import PythonRepoManager
 from codemodder.registry import load_registered_codemods
 
 
+@pytest.fixture(autouse=True)
+def disable_write_dependencies(mocker):
+    """
+    Unit tests should not write any dependency files
+    """
+    mocker.patch(
+        "codemodder.dependency_management.dependency_manager.DependencyManager.write",
+        # In conftest.py the return value is set to None
+        # We need a mocked value for the tests in this file
+    )
+
+
 class TestContext:
     def test_successful_dependency_description(self, mocker):
         registry = load_registered_codemods()