[processing][grass] Fix v.voronoi output type, add test

Author: nyalldawson

python/plugins/processing/algs/grass7/ext/v_voronoi.py

@@ -43,4 +43,4 @@ def processOutputs(alg, parameters, context, feedback):
     if alg.parameterAsBool(parameters, '-l', context):
         dataType = 'line'
 
-    alg.exportVectorLayer(grassName, fileName, dataType)
+    alg.exportVectorLayer(grassName, fileName, dataType=dataType)

python/plugins/processing/tests/testdata/expected/grass7/v_voronoi.dbf

@@ -0,0 +1 @@
+GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137,298.257223563]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]]

python/plugins/processing/tests/testdata/expected/grass7/v_voronoi.prj

@@ -68,3 +68,26 @@ tests:
       output:
         name: expected/grass7/v_rast_stats.shp
         type: vector
+
+  - algorithm: grass7:v.voronoi
+    name: v.voronoi
+    params:
+      -a: false
+      -l: false
+      -s: false
+      -t: false
+      GRASS_MIN_AREA_PARAMETER: 0.0001
+      GRASS_OUTPUT_TYPE_PARAMETER: 0
+      GRASS_SNAP_TOLERANCE_PARAMETER: -1.0
+      GRASS_VECTOR_DSCO: ''
+      GRASS_VECTOR_LCO: ''
+      input:
+        name: points.gml
+        type: vector
+      smoothness: 0.25
+      thin: -1.0
+    results:
+      output:
+        name: expected/grass7/v_voronoi.shp
+        type: vector
+