diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..c18dd8d
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+__pycache__/
diff --git a/testr/__init__.py b/testr/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/testr/file_data.py b/testr/file_data.py
new file mode 100644
index 0000000..c51b5c9
--- /dev/null
+++ b/testr/file_data.py
@@ -0,0 +1,79 @@
+import asyncio
+from testr.runner import TestData, TestRunner, TestStatus, TestSuite, StatusCode
+from pathlib import Path
+
+
+class FileData(TestData):
+    """Backend to parse test data from files."""
+
+    def __init__(self, input_file: Path, output_file: Path):
+        if not input_file.is_file():
+            raise ValueError(f"input_file must be a file, got '{input_file}'")
+        if not output_file.is_file():
+            raise ValueError(f"output_file must be a file, got '{output_file}'")
+        self.input_file = input_file
+        self.output_file = output_file
+
+    async def get_input(self) -> str:
+        with open(self.input_file, "r") as f:
+            return f.read()
+
+    async def validate_output(self, output: str) -> bool:
+        with open(self.output_file, "r") as f:
+            correct = f.read()
+            return correct == output
+
+
+class ExecutableRunner(TestRunner):
+    def __init__(self, executable: Path):
+        if not executable.is_file():
+            raise ValueError(f"executable must be a file, got '{executable}'")
+        self.executable = executable
+
+    async def run_test(self, data: TestData) -> TestStatus:
+        proc = await asyncio.create_subprocess_shell(
+                str(self.executable),
+                stdout=asyncio.subprocess.PIPE,
+                stderr=asyncio.subprocess.PIPE,
+                stdin=asyncio.subprocess.PIPE,
+            )
+
+        input_data = (await data.get_input()).encode()
+
+        try:
+            out_stream, err_stream = await asyncio.wait_for(
+                    proc.communicate(input=input_data), timeout=5.0)
+        except TimeoutError:
+            proc.kill()
+            return TestStatus(code=StatusCode.TLE, stderr="", stdout="")
+
+        stdout: str = out_stream.decode()
+        stderr: str = err_stream.decode()
+
+        if proc.returncode != 0:
+            return TestStatus(code=StatusCode.IR, stdout=stdout, stderr=stderr)
+
+        correct: bool = await data.validate_output(stdout)
+        ret_code = StatusCode.AC if correct else StatusCode.WA
+        return TestStatus(code=ret_code, stdout=stdout, stderr=stderr)
+
+
+class DirectorySuite(TestSuite):
+    """Loader for .in, .out files in a directory."""
+
+    def __init__(self, test_dir: Path):
+        self.test_cases = []
+
+        if not test_dir.is_dir():
+            raise ValueError(f"test_dir must be a directory, got '{test_dir}'")
+        for inp_file in test_dir.glob("*.in"):
+            if not inp_file.is_file:
+                continue
+            outp_file = inp_file.with_suffix("out")
+            if not outp_file.is_file():
+                raise ValueError(f"output file '{outp_file}' is not a valid file")
+            self.test_cases.append(FileData(inp_file, outp_file))
+
+
+    def __iter__(self):
+        return self.test_cases.__iter__()
diff --git a/testr/runner.py b/testr/runner.py
index 8209a12..9ef7a40 100644
--- a/testr/runner.py
+++ b/testr/runner.py
@@ -1,10 +1,12 @@
+from dataclasses import dataclass
 from abc import ABC, abstractmethod
+from collections.abc import Iterable
 from enum import Enum, auto
 
 
-class TestStatus(Enum):
+class StatusCode(Enum):
     """
-    Status of an individual test case.
+    Status codes for an individual test case.
     """
 
     AC = auto()
@@ -19,39 +21,52 @@ class TestStatus(Enum):
     """
     Time Limit Exceeded: program took too long to execute this case.
     """
-    WJ = auto()
+    IR = auto()
     """
-    Waiting for Judgement: this test case has not been finished yet.
+    Invalid Return: program did not return 0
     """
 
 
-class TestData(ABC):
-    """Input and output for single test case."""
+@dataclass
+class TestStatus:
+    """
+    Status of an individual test case.
+    """
+    
+    code: StatusCode
+    stderr: str
+    stdout: str
+
+
+class TestInput(ABC):
+    """Input provider for single test case."""
 
     @abstractmethod
-    def get_input(self) -> str: pass
+    async def get_input(self) -> str: pass
+
+
+class TestValidator(ABC):
+    """Output validator for single test case."""
 
     @abstractmethod
-    async def validate_output(self) -> bool: pass
+    async def validate_output(self, output: str) -> bool: pass
 
 
-class TestCase(ABC):
-    """Runner for a single test case."""
+class TestData(TestInput, TestValidator):
+    """Combined input/output for single test case"""
 
-    def __init__(self, data: TestData):
-        self.test_data = data
-        super().__init__()
+    pass
 
-    @property
-    @abstractmethod
-    def status(self) -> TestStatus: pass
+
+class TestRunner(ABC):
+    """Runner for test cases."""
 
     @abstractmethod
-    async def run_test(self) -> None: pass
+    async def run_test(self, data: TestData) -> StatusCode: pass
 
 
 class TestSuite(ABC):
     """Loader for multiple test cases."""
 
     @abstractmethod
-    def __next__(self) -> TestCase: pass
+    def __iter__(self) -> Iterable[TestData]: pass