diff --git a/tests/test_workflow_validator.py b/tests/test_workflow_validator.py
deleted file mode 100644
index 353b3cc..0000000
--- a/tests/test_workflow_validator.py
+++ /dev/null
@@ -1,44 +0,0 @@
-import os
-from typing import Any
-
-import pytest
-import yaml
-
-pytestmark = pytest.mark.unit
-
-from tests.test_decoder import _MINIMAL_WORKFLOW
-from workflow.workflow_validator import ValidationLevel, WorkflowValidator
-
-
-def test_validate_minimal_for_create():
-    # Arrange
-
-    # Act
-    error = WorkflowValidator.validate(
-        level=ValidationLevel.CREATE,
-        workflow_definition=_MINIMAL_WORKFLOW,
-    )
-
-    # Assert
-    assert error.error_num == 0
-    assert error.error_msg is None
-
-
-def test_validate_example_smiles_to_file_for_create():
-    # Arrange
-    workflow_file: str = os.path.join(
-        os.path.dirname(__file__), "workflow-definitions", "example-smiles-to-file.yaml"
-    )
-    with open(workflow_file, "r", encoding="utf8") as workflow_file:
-        workflow: dict[str, Any] = yaml.load(workflow_file, Loader=yaml.FullLoader)
-    assert workflow
-
-    # Act
-    error = WorkflowValidator.validate(
-        level=ValidationLevel.CREATE,
-        workflow_definition=workflow,
-    )
-
-    # Assert
-    assert error.error_num == 0
-    assert error.error_msg is None
diff --git a/tests/test_workflow_validator_for_create_level.py b/tests/test_workflow_validator_for_create_level.py
new file mode 100644
index 0000000..f42555c
--- /dev/null
+++ b/tests/test_workflow_validator_for_create_level.py
@@ -0,0 +1,104 @@
+import os
+from typing import Any
+
+import pytest
+import yaml
+
+pytestmark = pytest.mark.unit
+
+from tests.test_decoder import _MINIMAL_WORKFLOW
+from workflow.workflow_validator import ValidationLevel, WorkflowValidator
+
+
+def test_validate_minimal():
+    # Arrange
+
+    # Act
+    error = WorkflowValidator.validate(
+        level=ValidationLevel.CREATE,
+        workflow_definition=_MINIMAL_WORKFLOW,
+    )
+
+    # Assert
+    assert error.error_num == 0
+    assert error.error_msg is None
+
+
+def test_validate_example_nop_file():
+    # Arrange
+    workflow_file: str = os.path.join(
+        os.path.dirname(__file__), "workflow-definitions", "example-nop-fail.yaml"
+    )
+    with open(workflow_file, "r", encoding="utf8") as workflow_file:
+        workflow: dict[str, Any] = yaml.load(workflow_file, Loader=yaml.FullLoader)
+    assert workflow
+
+    # Act
+    error = WorkflowValidator.validate(
+        level=ValidationLevel.CREATE,
+        workflow_definition=workflow,
+    )
+
+    # Assert
+    assert error.error_num == 0
+    assert error.error_msg is None
+
+
+def test_validate_example_smiles_to_file():
+    # Arrange
+    workflow_file: str = os.path.join(
+        os.path.dirname(__file__), "workflow-definitions", "example-smiles-to-file.yaml"
+    )
+    with open(workflow_file, "r", encoding="utf8") as workflow_file:
+        workflow: dict[str, Any] = yaml.load(workflow_file, Loader=yaml.FullLoader)
+    assert workflow
+
+    # Act
+    error = WorkflowValidator.validate(
+        level=ValidationLevel.CREATE,
+        workflow_definition=workflow,
+    )
+
+    # Assert
+    assert error.error_num == 0
+    assert error.error_msg is None
+
+
+def test_validate_example_tow_step_nop():
+    # Arrange
+    workflow_file: str = os.path.join(
+        os.path.dirname(__file__), "workflow-definitions", "example-two-step-nop.yaml"
+    )
+    with open(workflow_file, "r", encoding="utf8") as workflow_file:
+        workflow: dict[str, Any] = yaml.load(workflow_file, Loader=yaml.FullLoader)
+    assert workflow
+
+    # Act
+    error = WorkflowValidator.validate(
+        level=ValidationLevel.CREATE,
+        workflow_definition=workflow,
+    )
+
+    # Assert
+    assert error.error_num == 0
+    assert error.error_msg is None
+
+
+def test_validate_shortcut_example_1():
+    # Arrange
+    workflow_file: str = os.path.join(
+        os.path.dirname(__file__), "workflow-definitions", "shortcut-example-1.yaml"
+    )
+    with open(workflow_file, "r", encoding="utf8") as workflow_file:
+        workflow: dict[str, Any] = yaml.load(workflow_file, Loader=yaml.FullLoader)
+    assert workflow
+
+    # Act
+    error = WorkflowValidator.validate(
+        level=ValidationLevel.CREATE,
+        workflow_definition=workflow,
+    )
+
+    # Assert
+    assert error.error_num == 0
+    assert error.error_msg is None
diff --git a/tests/test_workflow_validator_for_run_level.py b/tests/test_workflow_validator_for_run_level.py
new file mode 100644
index 0000000..4aa0947
--- /dev/null
+++ b/tests/test_workflow_validator_for_run_level.py
@@ -0,0 +1,89 @@
+import os
+from typing import Any
+
+import pytest
+import yaml
+
+pytestmark = pytest.mark.unit
+
+from workflow.workflow_validator import ValidationLevel, WorkflowValidator
+
+
+def test_validate_example_nop_file():
+    # Arrange
+    workflow_file: str = os.path.join(
+        os.path.dirname(__file__), "workflow-definitions", "example-nop-fail.yaml"
+    )
+    with open(workflow_file, "r", encoding="utf8") as workflow_file:
+        workflow: dict[str, Any] = yaml.load(workflow_file, Loader=yaml.FullLoader)
+    assert workflow
+
+    # Act
+    error = WorkflowValidator.validate(
+        level=ValidationLevel.RUN,
+        workflow_definition=workflow,
+    )
+
+    # Assert
+    assert error.error_num == 0
+    assert error.error_msg is None
+
+
+def test_validate_example_smiles_to_file():
+    # Arrange
+    workflow_file: str = os.path.join(
+        os.path.dirname(__file__), "workflow-definitions", "example-smiles-to-file.yaml"
+    )
+    with open(workflow_file, "r", encoding="utf8") as workflow_file:
+        workflow: dict[str, Any] = yaml.load(workflow_file, Loader=yaml.FullLoader)
+    assert workflow
+
+    # Act
+    error = WorkflowValidator.validate(
+        level=ValidationLevel.RUN,
+        workflow_definition=workflow,
+    )
+
+    # Assert
+    assert error.error_num == 0
+    assert error.error_msg is None
+
+
+def test_validate_example_tow_step_nop():
+    # Arrange
+    workflow_file: str = os.path.join(
+        os.path.dirname(__file__), "workflow-definitions", "example-two-step-nop.yaml"
+    )
+    with open(workflow_file, "r", encoding="utf8") as workflow_file:
+        workflow: dict[str, Any] = yaml.load(workflow_file, Loader=yaml.FullLoader)
+    assert workflow
+
+    # Act
+    error = WorkflowValidator.validate(
+        level=ValidationLevel.RUN,
+        workflow_definition=workflow,
+    )
+
+    # Assert
+    assert error.error_num == 0
+    assert error.error_msg is None
+
+
+def test_validate_shortcut_example_1():
+    # Arrange
+    workflow_file: str = os.path.join(
+        os.path.dirname(__file__), "workflow-definitions", "shortcut-example-1.yaml"
+    )
+    with open(workflow_file, "r", encoding="utf8") as workflow_file:
+        workflow: dict[str, Any] = yaml.load(workflow_file, Loader=yaml.FullLoader)
+    assert workflow
+
+    # Act
+    error = WorkflowValidator.validate(
+        level=ValidationLevel.RUN,
+        workflow_definition=workflow,
+    )
+
+    # Assert
+    assert error.error_num == 0
+    assert error.error_msg is None
diff --git a/workflow/workflow_engine.py b/workflow/workflow_engine.py
index 7ba43ea..9128d05 100644
--- a/workflow/workflow_engine.py
+++ b/workflow/workflow_engine.py
@@ -304,22 +304,22 @@ def _validate_step_command(
         # and can be launched. If it is False then the returned str contains an
         # error message.
         #
-        # Remember that variables can exist in (ascending order of priority): -
+        # Remember that variables can exist in the specification too.
+        # So, the full set of step variables (in ascending order of priority)
+        # is...
+        #
         # 1. The specification
         # 2. The workflow
-        # 2. The RunningWorkflow
+        # 3. The RunningWorkflow
 
-        all_variables: dict[str, Any] = {}
-        if "variables" in step_spec:
-            all_variables = step_spec.pop("variables")
+        all_variables = step_spec.pop("variables") if "variables" in step_spec else {}
         if workflow_variables:
-            all_variables = all_variables | workflow_variables
+            all_variables |= workflow_variables
         if running_workflow_variables:
-            all_variables = all_variables | running_workflow_variables
+            all_variables |= running_workflow_variables
         message, success = decode(
             job["command"], all_variables, "command", TextEncoding.JINJA2_3_0
         )
-
         return all_variables if success else message
 
     def _launch(
diff --git a/workflow/workflow_validator.py b/workflow/workflow_validator.py
index db6f6e9..8040fd2 100644
--- a/workflow/workflow_validator.py
+++ b/workflow/workflow_validator.py
@@ -72,35 +72,36 @@ def _validate_run_level(
         assert workflow_definition
         del workflow_inputs
 
-        # RUN level requires that the specification is a valid JSON string.
+        # RUN level requires that each step specification is a valid JSON string.
         # and contains properties for 'collection', 'job', and 'version'.
-        try:
-            specification = json.loads(workflow_definition["specification"])
-        except json.decoder.JSONDecodeError as e:
-            return ValidationResult(
-                error_num=1,
-                error_msg=[
-                    f"Error decoding specification, which is not valid JSON: {e}"
-                ],
-            )
-        except TypeError as e:
-            return ValidationResult(
-                error_num=2,
-                error_msg=[
-                    f"Error decoding specification, which is not valid JSON: {e}"
-                ],
-            )
-        expected_keys: set[str] = {"collection", "job", "version"}
-        missing_keys: list[str] = []
-        missing_keys.extend(
-            expected_key
-            for expected_key in expected_keys
-            if expected_key not in specification
-        )
-        if missing_keys:
-            return ValidationResult(
-                error_num=2,
-                error_msg=[f"Specification is missing: {', '.join(missing_keys)}"],
+        for step in workflow_definition["steps"]:
+            try:
+                specification = json.loads(step["specification"])
+            except json.decoder.JSONDecodeError as e:
+                return ValidationResult(
+                    error_num=2,
+                    error_msg=[
+                        f"Error decoding specification, which is not valid JSON: {e}"
+                    ],
+                )
+            except TypeError as e:
+                return ValidationResult(
+                    error_num=3,
+                    error_msg=[
+                        f"Error decoding specification, which is not valid JSON: {e}"
+                    ],
+                )
+            expected_keys: set[str] = {"collection", "job", "version"}
+            missing_keys: list[str] = []
+            missing_keys.extend(
+                expected_key
+                for expected_key in expected_keys
+                if expected_key not in specification
             )
+            if missing_keys:
+                return ValidationResult(
+                    error_num=2,
+                    error_msg=[f"Specification is missing: {', '.join(missing_keys)}"],
+                )
 
         return _VALIDATION_SUCCESS