pick_value implement format_souce

which gives the workflow editor the needed info for the
output's data type. otherwise connection to downstream tools
(in particular if multiple datatypes were possble, eg fasta,fasta.gz)
were not possible.

I adapted and added tests to check for ftypes, to ensure
that empty first repeat element does not create trouble.

the workflow functionality has been tested manually.

reverts the previous commit for now

tools/pick_value/pick_value.xml

@@ -1,4 +1,4 @@
-<tool name="Pick parameter value" id="pick_value" version="0.1.0" profile="21.01" tool_type="expression">
+<tool name="Pick parameter value" id="pick_value" version="0.2.0" profile="21.01" tool_type="expression">
     <macros>
         <xml name="booleans">
             <repeat name="pick_from" title="Pick from">
@@ -146,7 +146,11 @@ return { 'output': out };
         <output type="boolean" name="boolean_param" from="output">
             <filter>style_cond['type_cond']['param_type'] == 'boolean'</filter>
         </output>
-        <output type="data" name="data_param" from="output">
+        <!-- Galaxy already copies the dataset with all its properties (including format)
+             in exec_after_process. setting the format_source here is in this sense
+             redundant, but helps the workflow editor to infer the data type
+             (from the dataset in the first repeat element) -->
+        <output type="data" name="data_param" from="output" format_source="style_cond|type_cond|pick_from_0|value">
             <filter>style_cond['type_cond']['param_type'] == 'data'</filter>
         </output>
     </outputs>
@@ -185,14 +189,14 @@ taken.
                         <param name="value" value_json="null" />
                     </repeat>
                     <repeat name="pick_from">
-                        <param name="value" value="simple_line.txt" />
+                        <param name="value" value="simple_line.txt" ftype="tsv"/>
                     </repeat>
                     <repeat name="pick_from">
-                        <param name="value" value="simple_line_alternative.txt" />
+                        <param name="value" value="simple_line_alternative.txt" ftype="csv" />
                     </repeat>
                 </conditional>
             </conditional>
-            <output name="data_param" value="simple_line.txt" />
+            <output name="data_param" value="simple_line.txt" ftype="tsv" />
         </test>
         <test expect_num_outputs="1">
             <conditional name="style_cond">
@@ -363,11 +367,30 @@ taken.
                     <repeat name="pick_from">
                         <param name="value" value_json="null" />
                     </repeat>
-                    <param name="default_value" value="simple_line.txt" />
+                    <param name="default_value" value="simple_line.txt" ftype="tsv" />
                 </conditional>
             </conditional>
-            <output name="data_param" value="simple_line.txt" />
+            <output name="data_param" value="simple_line.txt" ftype="tsv" />
         </test>
+
+        <!-- with first_or_default that the default is used if given -->
+        <test expect_num_outputs="1">
+            <conditional name="style_cond">
+                <param name="pick_style" value="first_or_default" />
+                <conditional name="type_cond">
+                    <param name="param_type" value="data" />
+                    <repeat name="pick_from">
+                        <param name="value" value_json="null" />
+                    </repeat>
+                    <repeat name="pick_from">
+                        <param name="value" value="simple_line.txt" ftype="csv" />
+                    </repeat>
+                    <param name="default_value" value="simple_line_alternative.txt" ftype="tabular" />
+                </conditional>
+            </conditional>
+            <output name="data_param" value="simple_line.txt" ftype="csv"/>
+        </test>
+
     </tests>
 </tool>