--lock without requirements installs the entire lock. (#1658)

Closes #1657.

Author: Eric-Arellano

pex/resolve/lock_resolver.py

@@ -117,7 +117,9 @@ def resolve_from_lock(
         )
         parsed_requirements = try_(
             parse_lockable_requirements(
-                requirement_configuration, network_configuration=network_configuration
+                requirement_configuration,
+                network_configuration=network_configuration,
+                fallback_requirements=(str(req) for req in lock.requirements),
             )
         )
 

pex/resolve/lockfile/__init__.py

@@ -15,6 +15,7 @@
     PyPIRequirement,
     URLRequirement,
     VCSRequirement,
+    parse_requirement_strings,
 )
 from pex.resolve import resolvers
 from pex.resolve.locked_resolve import Artifact, LockConfiguration
@@ -124,12 +125,17 @@ def create(
 def parse_lockable_requirements(
     requirement_configuration,  # type: RequirementConfiguration
     network_configuration=None,  # type: Optional[NetworkConfiguration]
+    fallback_requirements=None,  # type: Optional[Iterable[str]]
 ):
     # type: (...) -> Union[Requirements, Error]
 
+    all_parsed_requirements = requirement_configuration.parse_requirements(network_configuration)
+    if not all_parsed_requirements and fallback_requirements:
+        all_parsed_requirements = parse_requirement_strings(fallback_requirements)
+
     parsed_requirements = []  # type: List[Union[PyPIRequirement, URLRequirement]]
     projects = []  # type: List[str]
-    for parsed_requirement in requirement_configuration.parse_requirements(network_configuration):
+    for parsed_requirement in all_parsed_requirements:
         if isinstance(parsed_requirement, LocalProjectRequirement):
             projects.append("local project at {path}".format(path=parsed_requirement.path))
         elif isinstance(parsed_requirement, VCSRequirement):

pex/resolve/resolver_options.py

@@ -119,8 +119,9 @@ def register(
             default=None,
             type=str,
             help=(
-                "Resolve requirements from the given lock file instead of from --index servers, "
-                "--find-links repos or a --pex-repository."
+                "Resolve requirements from the given lock file crated by Pex instead of from "
+                "--index servers, --find-links repos or a --pex-repository. If no requirements are "
+                "specified, will install the entire lock."
             ),
         )
 

tests/integration/test_lock_resolver.py

@@ -111,21 +111,25 @@ def test_subset(
     # type: (...) -> None
 
     urllib3_pex = os.path.join(str(tmpdir), "urllib3.pex")
-    run_pex_command(
-        args=[
-            "--lock",
-            requests_lock_strict,
-            "urllib3",
-            "-o",
-            urllib3_pex,
-            "--",
-            "-c",
-            "import urllib3",
-        ]
-    ).assert_success()
+
+    def args(*requirements):
+        return (
+            ["--lock", requests_lock_strict, "-o", urllib3_pex]
+            + list(requirements)
+            + ["--", "-c", "import urllib3"]
+        )
+
+    run_pex_command(args("urllib3")).assert_success()
     pex_distributions = index_pex_distributions(urllib3_pex)
-    assert ProjectName("requests") not in pex_distributions
     assert ProjectName("urllib3") in pex_distributions
+    for project in ("requests", "idna", "chardet", "certifi"):
+        assert ProjectName(project) not in pex_distributions
+
+    # However, if no requirements are specified, resolve the entire lock.
+    run_pex_command(args()).assert_success()
+    pex_distributions = index_pex_distributions(urllib3_pex)
+    for project in ("requests", "urllib3", "idna", "chardet", "certifi"):
+        assert ProjectName(project) in pex_distributions
 
 
 def test_empty_lock_issue_1659(tmpdir):