spec clarification and tests for empty scatter

Author: Luka Stojanovic

v1.0/Workflow.yml

@@ -345,6 +345,9 @@ $graph:
     All output parameter types are also implicitly wrapped in arrays.  Each job
     in the scatter results in an entry in the output array.
 
+    If a scattered input is an empty list, step can be skipped, and all of it's
+    outputs set to an empty list(s), according to applicable scattering rules.
+
     If `scatter` declares more than one input parameter, `scatterMethod`
     describes how to decompose the input into a discrete set of jobs.
 

v1.0/conformance_test_v1.0.yaml

@@ -256,6 +256,36 @@
   tool: "v1.0/scatter-wf4.cwl#main"
   doc: Test workflow scatter with two scatter parameters and dotproduct join method
 
+- job: v1.0/scatter-empty-job1.json
+  output:
+    out: []
+  tool: v1.0/scatter-wf1.cwl
+  doc: Test workflow scatter with single empty list parameter
+
+- job: v1.0/scatter-empty-job2.json
+  output:
+    out: [[], []]
+  tool: v1.0/scatter-wf2.cwl
+  doc: Test workflow scatter with two scatter parameters and nested_crossproduct join method with second list empty
+
+- job: v1.0/scatter-empty-job3.json
+  output:
+    out: []
+  tool: "v1.0/scatter-wf3.cwl#main"
+  doc: Test workflow scatter with two scatter parameters and nested_crossproduct join method with first list empty
+
+- job: v1.0/scatter-empty-job2.json
+  output:
+    out: []
+  tool: "v1.0/scatter-wf3.cwl#main"
+  doc: Test workflow scatter with two scatter parameters, one of which is empty and flat_crossproduct join method
+
+- job: v1.0/scatter-empty-job4.json
+  output:
+    out: []
+  tool: "v1.0/scatter-wf4.cwl#main"
+  doc: Test workflow scatter with two empty scatter parameters and dotproduct join method
+
 - tool: v1.0/echo-tool.cwl
   job: v1.0/env-job.json
   output:

v1.1.0-dev1/Workflow.yml

@@ -352,6 +352,9 @@ $graph:
     All output parameter types are also implicitly wrapped in arrays.  Each job
     in the scatter results in an entry in the output array.
 
+    If a scattered input is an empty list, step can be skipped, and all of it's
+    outputs set to an empty list(s), according to applicable scattering rules.
+
     If `scatter` declares more than one input parameter, `scatterMethod`
     describes how to decompose the input into a discrete set of jobs.
 

v1.1.0-dev1/conformance_test_v1.1.0-dev1.yaml

@@ -267,6 +267,36 @@
   tool: "v1.1.0-dev1/scatter-wf4.cwl#main"
   doc: Test workflow scatter with two scatter parameters and dotproduct join method
 
+- job: v1.0/scatter-empty-job1.json
+  output:
+    out: []
+  tool: v1.0/scatter-wf1.cwl
+  doc: Test workflow scatter with single empty list parameter
+
+- job: v1.0/scatter-empty-job2.json
+  output:
+    out: [[], []]
+  tool: v1.0/scatter-wf2.cwl
+  doc: Test workflow scatter with two scatter parameters and nested_crossproduct join method with second list empty
+
+- job: v1.0/scatter-empty-job3.json
+  output:
+    out: []
+  tool: "v1.0/scatter-wf3.cwl#main"
+  doc: Test workflow scatter with two scatter parameters and nested_crossproduct join method with first list empty
+
+- job: v1.0/scatter-empty-job2.json
+  output:
+    out: []
+  tool: "v1.0/scatter-wf3.cwl#main"
+  doc: Test workflow scatter with two scatter parameters, one of which is empty and flat_crossproduct join method
+
+- job: v1.0/scatter-empty-job4.json
+  output:
+    out: []
+  tool: "v1.0/scatter-wf4.cwl#main"
+  doc: Test workflow scatter with two empty scatter parameters and dotproduct join method
+
 - tool: v1.1.0-dev1/echo-tool.cwl
   job: v1.1.0-dev1/env-job.json
   output:

v1.1.0-dev1/v1.1.0-dev1/scatter-empty-job1.json

@@ -0,0 +1,3 @@
+{
+  "inp": []
+}

v1.1.0-dev1/v1.1.0-dev1/scatter-empty-job2.json

@@ -0,0 +1,4 @@
+{
+  "inp1": ["one", "two"],
+  "inp2": []
+}

v1.1.0-dev1/v1.1.0-dev1/scatter-empty-job3.json

@@ -0,0 +1,4 @@
+{
+  "inp1": [],
+  "inp2": ["one", "two"]
+}

v1.1.0-dev1/v1.1.0-dev1/scatter-empty-job4.json

@@ -0,0 +1,4 @@
+{
+  "inp1": [],
+  "inp2": []
+}