diff --git a/lib/private/action_subject.bzl b/lib/private/action_subject.bzl
index c9e21eb..54fe849 100644
--- a/lib/private/action_subject.bzl
+++ b/lib/private/action_subject.bzl
@@ -67,6 +67,7 @@ def _action_subject_new(action, meta):
         meta = meta,
         mnemonic = mkmethod(self, _action_subject_mnemonic),
         not_contains_arg = mkmethod(self, _action_subject_not_contains_arg),
+        outputs = mkmethod(self, _action_subject_outputs),
         substitutions = mkmethod(self, _action_subject_substitutions),
         # keep sorted end
     )
@@ -226,6 +227,17 @@ def _action_subject_inputs(self):
     meta = self.meta.derive("inputs()")
     return DepsetFileSubject.new(self.action.inputs, meta)
 
+def _action_subject_outputs(self):
+    """Returns a DepsetFileSubject for the action's outputs.
+
+    Method: ActionSubject.outputs
+
+    Returns:
+        `DepsetFileSubject` of the action's outputs.
+    """
+    meta = self.meta.derive("outputs()")
+    return DepsetFileSubject.new(self.action.outputs, meta)
+
 def _action_subject_contains_flag_values(self, flag_values):
     """Assert that an action's argv has the given ("--flag", "value") entries.
 
diff --git a/lib/private/depset_file_subject.bzl b/lib/private/depset_file_subject.bzl
index fc7df70..fe5a20b 100644
--- a/lib/private/depset_file_subject.bzl
+++ b/lib/private/depset_file_subject.bzl
@@ -61,6 +61,7 @@ def _depset_file_subject_new(files, meta, container_name = "depset", element_plu
         contains_exactly = lambda *a, **k: _depset_file_subject_contains_exactly(self, *a, **k),
         contains_none_of = lambda *a, **k: _depset_file_subject_contains_none_of(self, *a, **k),
         contains_predicate = lambda *a, **k: _depset_file_subject_contains_predicate(self, *a, **k),
+        has_size = lambda *a, **k: _depset_file_subject_has_size(self, *a, **k),
         is_empty = lambda *a, **k: _depset_file_subject_is_empty(self, *a, **k),
         is_not_empty = lambda *a, **k: _depset_file_subject_is_not_empty(self, *a, **k),
         not_contains = lambda *a, **k: _depset_file_subject_not_contains(self, *a, **k),
@@ -77,6 +78,22 @@ def _depset_file_subject_new(files, meta, container_name = "depset", element_plu
     )
     return public
 
+def _depset_file_subject_has_size(self, expected):
+    """Asserts that `expected` is the size of the depset of files.
+
+    Method: DepsetFileSubject.has_size
+
+    Args:
+        self: implicitly added.
+        expected: ([`int`]) the expected size of the depset of files.
+    """
+    return CollectionSubject.new(
+        self.files,
+        meta = self.meta,
+        container_name = self.container_name,
+        element_plural_name = self.element_plural_name,
+    ).has_size(expected)
+
 def _depset_file_subject_is_empty(self):
     """Asserts that the depset of files is empty.