diff --git a/app/tests/test_validator.py b/app/tests/test_validator.py
new file mode 100644
index 0000000..c86bd52
--- /dev/null
+++ b/app/tests/test_validator.py
@@ -0,0 +1,79 @@
+"""Tests for validation module."""
+
+import pytest
+from pathlib import Path
+import tempfile
+
+
+class TestValidator:
+    """Test cases for schema validation."""
+
+    def test_validate_missing_required(self):
+        """Test validation catches missing required variables."""
+        from env_pro.core.validator import Validator, Schema, VarSchema
+
+        schema = Schema(variables={
+            "DATABASE_URL": VarSchema(required=True),
+            "API_KEY": VarSchema(required=True),
+        })
+
+        validator = Validator(schema)
+        errors = validator.validate({"DATABASE_URL": "some-url"})
+
+        error_keys = [e.key for e in errors]
+        assert "API_KEY" in error_keys
+
+    def test_validate_pattern_mismatch(self):
+        """Test validation catches pattern mismatches."""
+        from env_pro.core.validator import Validator, Schema, VarSchema
+
+        schema = Schema(variables={
+            "PORT": VarSchema(type="int", pattern=r"^\d+$"),
+        })
+
+        validator = Validator(schema)
+        errors = validator.validate({"PORT": "abc"})
+
+        assert len(errors) > 0
+        assert errors[0].key == "PORT"
+
+    def test_validate_min_length(self):
+        """Test validation checks minimum length."""
+        from env_pro.core.validator import Validator, Schema, VarSchema
+
+        schema = Schema(variables={
+            "PASSWORD": VarSchema(min_length=8),
+        })
+
+        validator = Validator(schema)
+        errors = validator.validate({"PASSWORD": "short"})
+
+        assert len(errors) > 0
+        assert "PASSWORD" in [e.key for e in errors]
+
+    def test_from_file_no_schema(self, temp_dir):
+        """Test loading validator when no schema file exists."""
+        from env_pro.core.validator import Validator
+
+        import os
+        os.chdir(temp_dir)
+
+        validator = Validator.from_file()
+        assert validator.schema is None
+
+    def test_from_file_with_schema(self, temp_dir):
+        """Test loading validator with schema file."""
+        from env_pro.core.validator import Validator
+
+        schema_content = """variables:
+  DATABASE_URL:
+    type: url
+    required: true
+"""
+        (temp_dir / ".env.schema.yaml").write_text(schema_content)
+
+        import os
+        os.chdir(temp_dir)
+
+        validator = Validator.from_file()
+        assert validator.schema is not None