fix: Crash on some invalid URLs in schema CLI option

docs/changelog.rst

@@ -12,6 +12,7 @@ Fixed
 - Crash on invalid regular expressions in ``method``, ``endpoint`` and ``tag`` CLI options. `#403`_
 - Crash on non latin-1 encodable value in ``auth`` CLI option. `#404`_
 - Crash on invalid value in ``header`` CLI options. `#405`_
+- Crash on some invalid URLs in ``schema`` CLI option. `#406`_
 
 `0.24.1`_ - 2020-02-08
 ----------------------
@@ -694,6 +695,7 @@ Fixed
 .. _0.3.0: https://github.com/kiwicom/schemathesis/compare/v0.2.0...v0.3.0
 .. _0.2.0: https://github.com/kiwicom/schemathesis/compare/v0.1.0...v0.2.0
 
+.. _#406: https://github.com/kiwicom/schemathesis/issues/406
 .. _#405: https://github.com/kiwicom/schemathesis/issues/405
 .. _#404: https://github.com/kiwicom/schemathesis/issues/404
 .. _#403: https://github.com/kiwicom/schemathesis/issues/403

src/schemathesis/cli/callbacks.py

@@ -6,6 +6,7 @@
 
 import click
 import hypothesis
+from requests import PreparedRequest, RequestException
 
 from .. import utils
 
@@ -16,9 +17,18 @@ def validate_schema(ctx: click.core.Context, param: click.core.Parameter, raw_va
             raise click.UsageError("Invalid SCHEMA, must be a valid URL or file path.")
         if "base_url" not in ctx.params:
             raise click.UsageError('Missing argument, "--base-url" is required for SCHEMA specified by file.')
+    else:
+        _validate_url(raw_value)
     return raw_value
 
 
+def _validate_url(value: str) -> None:
+    try:
+        PreparedRequest().prepare_url(value, {})  # type: ignore
+    except RequestException:
+        raise click.UsageError("Invalid SCHEMA, must be a valid URL or file path.")
+
+
 def validate_base_url(ctx: click.core.Context, param: click.core.Parameter, raw_value: str) -> str:
     if raw_value and not urlparse(raw_value).netloc:
         raise click.UsageError("Invalid base URL")

test/cli/test_callbacks.py

@@ -12,6 +12,7 @@
 
 @given(value=st.text().filter(lambda x: "//" not in x))
 @example("0" * 1000)
+@example("//test")
 def test_validate_schema(value):
     with pytest.raises(click.UsageError):
         callbacks.validate_schema(SimpleNamespace(params={}), None, value)