diff --git a/sdks/python/apache_beam/yaml/readme_test.py b/sdks/python/apache_beam/yaml/readme_test.py
index efce92490a359..555d1d0b583f2 100644
--- a/sdks/python/apache_beam/yaml/readme_test.py
+++ b/sdks/python/apache_beam/yaml/readme_test.py
@@ -55,6 +55,8 @@ def expand(self, inputs):
 
     def guess_name_and_type(expr):
       expr = expr.strip().replace('`', '')
+      if expr.endswith('*'):
+        return 'unknown', str
       parts = expr.split()
       if len(parts) >= 2 and parts[-2].lower() == 'as':
         name = parts[-1]
@@ -87,7 +89,7 @@ def guess_name_and_type(expr):
       return name, typ
 
     if m.group(1) == '*':
-      return inputs['PCOLLECTION'] | beam.Filter(lambda _: True)
+      return next(iter(inputs.values())) | beam.Filter(lambda _: True)
     else:
       output_schema = [
           guess_name_and_type(expr) for expr in m.group(1).split(',')
@@ -269,6 +271,22 @@ def test(self):
 
 def parse_test_methods(markdown_lines):
   # pylint: disable=too-many-nested-blocks
+
+  def extract_inputs(input_spec):
+    if not input_spec:
+      return set()
+    elif isinstance(input_spec, str):
+      return set([input_spec.split('.')[0]])
+    elif isinstance(input_spec, list):
+      return set.union(*[extract_inputs(v) for v in input_spec])
+    elif isinstance(input_spec, dict):
+      return set.union(*[extract_inputs(v) for v in input_spec.values()])
+    else:
+      raise ValueError("Misformed inputs: " + input_spec)
+
+  def extract_name(input_spec):
+    return input_spec.get('name', input_spec.get('type'))
+
   code_lines = None
   for ix, line in enumerate(markdown_lines):
     line = line.rstrip()
@@ -280,17 +298,23 @@ def parse_test_methods(markdown_lines):
       else:
         if code_lines:
           if code_lines[0].startswith('- type:'):
-            is_chain = not any('input:' in line for line in code_lines)
+            specs = yaml.load('\n'.join(code_lines), Loader=SafeLoader)
+            is_chain = not any('input' in spec for spec in specs)
+            if is_chain:
+              undefined_inputs = set(['input'])
+            else:
+              undefined_inputs = set.union(
+                  *[extract_inputs(spec.get('input')) for spec in specs]) - set(
+                      extract_name(spec) for spec in specs)
             # Treat this as a fragment of a larger pipeline.
             # pylint: disable=not-an-iterable
             code_lines = [
                 'pipeline:',
                 '  type: chain' if is_chain else '',
                 '  transforms:',
-                '    - type: ReadFromCsv',
-                '      name: input',
-                '      config:',
-                '        path: whatever',
+            ] + [
+                '    - {type: ReadFromCsv, name: "%s", config: {path: x}}' %
+                undefined_input for undefined_input in undefined_inputs
             ] + ['    ' + line for line in code_lines]
           if code_lines[0] == 'pipeline:':
             yaml_pipeline = '\n'.join(code_lines)
@@ -329,6 +353,9 @@ def createTestSuite(name, path):
 InlinePythonTest = createTestSuite(
     'InlinePythonTest', os.path.join(YAML_DOCS_DIR, 'yaml-inline-python.md'))
 
+JoinTest = createTestSuite(
+    'JoinTest', os.path.join(YAML_DOCS_DIR, 'yaml-join.md'))
+
 if __name__ == '__main__':
   parser = argparse.ArgumentParser()
   parser.add_argument('--render_dir', default=None)
diff --git a/sdks/python/apache_beam/yaml/yaml_join.py b/sdks/python/apache_beam/yaml/yaml_join.py
index 04a24642c2317..5124ef56b49c1 100644
--- a/sdks/python/apache_beam/yaml/yaml_join.py
+++ b/sdks/python/apache_beam/yaml/yaml_join.py
@@ -173,8 +173,9 @@ def _is_connected(edge_list, expected_node_count):
 def _SqlJoinTransform(
     pcolls,
     sql_transform_constructor,
-    type: Union[str, Dict[str, List]],
+    *,
     equalities: Union[str, List[Dict[str, str]]],
+    type: Union[str, Dict[str, List]] = 'inner',
     fields: Optional[Dict[str, Any]] = None):
   """Joins two or more inputs using a specified condition.
 
diff --git a/website/www/site/content/en/documentation/sdks/yaml-join.md b/website/www/site/content/en/documentation/sdks/yaml-join.md
index d207926ff995b..6645d7a945a34 100644
--- a/website/www/site/content/en/documentation/sdks/yaml-join.md
+++ b/website/www/site/content/en/documentation/sdks/yaml-join.md
@@ -48,7 +48,7 @@ inputs, one can use the following  shorthand syntax:
     input2: Second Input
     input3: Third Input
   config:
-    equalities: col
+    equalities: col1
 ```
 
 ## Join Types