[core] String formatting of parameters with/without quotes to deal with spaces in strings

We have the problem of spaces in file paths, choices (like colorspace),
etc.
An empty list is not send to the command line.
An empty string is send to the command line as "".
Add new unit test to ensure it follows the expected rules.

tests/test_nodeCommandLineFormatting.py

@@ -0,0 +1,72 @@
+#!/usr/bin/env python
+# coding:utf-8
+import os
+import tempfile
+
+import meshroom.multiview
+from meshroom.core.graph import Graph
+from meshroom.core.node import Node
+
+
+def test_formatting_listOfFiles():
+    inputImages = ['/non/existing/fileA', '/non/existing/with space/fileB']
+
+    graph = Graph('')
+    n1 = graph.addNewNode('CameraInit')
+    n1.viewpoints.extend([{'path': image} for image in inputImages])
+    # viewId, poseId, path, intrinsicId, rigId, subPoseId, metadata
+    assert n1.viewpoints.getValueStr() == '-1 -1 "/non/existing/fileA" -1 -1 -1 "" -1 -1 "/non/existing/with space/fileB" -1 -1 -1 ""'
+
+    assert n1.allowedCameraModels.getValueStr() == '"pinhole,radial1,radial3,brown,fisheye4,fisheye1,3deanamorphic4,3deradial4,3declassicld"'
+
+    graph = Graph('')
+    n1 = graph.addNewNode('ImageMatching')
+    assert n1.featuresFolders.getValueStr() == ''
+
+    n1.featuresFolders.extend("single value with space")
+    assert n1.featuresFolders.getValueStr() == '"single value with space"'
+
+    n1.featuresFolders.resetValue()
+    assert n1.featuresFolders.getValueStr() == ''
+
+    value = '"/non/existing/fileA" "/non/existing/with space/fileB"'
+    n1.featuresFolders.extend(inputImages)
+    assert n1.featuresFolders.getValueStr() == value
+
+    n1._buildCmdVars()  # prepare vars for command line creation
+    # and check some values
+    name = 'featuresFolders'
+    assert n1._cmdVars[name + 'Value'] == value
+
+
+def test_formatting_strings():
+    graph = Graph('')
+    n1 = graph.addNewNode('ImageMatching')
+    name = 'weights'
+    assert n1._cmdVars[name + 'Value'] == '""'  # Empty string should generate empty quotes
+    name = 'method'
+    assert n1._cmdVars[name + 'Value'] == '"SequentialAndVocabularyTree"'
+
+    n2 = graph.addNewNode('ImageMatching')
+    n2._buildCmdVars()  # prepare vars for command line creation
+    name = 'featuresFolders'
+    assert n2._cmdVars[name + 'Value'] == ''  # Empty list should become fully empty
+    n2.featuresFolders.extend('')
+    n2._buildCmdVars()  # prepare vars for command line creation
+    assert n2._cmdVars[name + 'Value'] == '""'  # A list with one empty string should generate empty quotes
+    n2.featuresFolders.extend('')
+    n2._buildCmdVars()  # prepare vars for command line creation
+    assert n2._cmdVars[name + 'Value'] == '"" ""'  # A list with 2 empty strings should generate quotes
+
+
+def test_formatting_groups():
+    graph = Graph('')
+    n3 = graph.addNewNode('ImageProcessing')
+    n3._buildCmdVars()  # prepare vars for command line creation
+    name = 'sharpenFilter'
+    assert n3._cmdVars[name + 'Value'] == 'False:3:1.0:0.0'
+    name = 'fillHoles'
+    assert n3._cmdVars[name + 'Value'] == 'False'  # Booleans
+    name = 'noiseFilter'
+    assert n3._cmdVars[name + 'Value'] == 'False:"uniform":0.0:1.0:True'
+