diff: Handle empty JSON files

Author: jonnor

examples/wholegraph.yml

@@ -0,0 +1,63 @@
+'added whole graph as .fbp':
+  from: ""
+  to: |
+    INPORT=ledchain.IN:PIXEL
+    OUTPORT=ledchain.PIXELSET:PIXELSET
+    ledchain(LedChain) SHOWN -> IN dummy(Forward)
+    ledchain READY -> IN dummyB(Forward)
+  diff: |
+    + INPORT=ledchain.IN:PIXEL
+    + OUTPORT=ledchain.PIXELSET:PIXELSET
+    + ledchain(LedChain)
+    + dummy(Forward)
+    + dummyB(Forward)
+    + ledchain SHOWN -> IN dummy
+    + ledchain READY -> IN dummyB
+
+'removed whole graph as .fbp':
+  from: |
+    INPORT=ledchain.IN:PIXEL
+    OUTPORT=ledchain.PIXELSET:PIXELSET
+    ledchain(LedChain) SHOWN -> IN dummy(Forward)
+    ledchain READY -> IN dummyB(Forward)
+  to: ""
+  diff: |
+    - INPORT=ledchain.IN:PIXEL
+    - OUTPORT=ledchain.PIXELSET:PIXELSET
+    - ledchain(LedChain)
+    - dummy(Forward)
+    - dummyB(Forward)
+    - ledchain SHOWN -> IN dummy
+    - ledchain READY -> IN dummyB
+
+'added whole graph as .json':
+  format: json
+  from: ""
+  to: |
+    {
+      "processes": {
+        "foo": { "component": "Bar" }
+      },
+      "connections": [
+        { "data": "my iip", "tgt": { "port": "IN", "process": "foo" } }
+      ]
+    }
+  diff: |
+    + foo(Bar)
+    + "my iip" -> IN foo
+
+'removed whole graph as .json':
+  format: json
+  from: |
+    {
+      "processes": {
+        "foo": { "component": "Bar" }
+      },
+      "connections": [
+        { "data": "my iip", "tgt": { "port": "IN", "process": "foo" } }
+      ]
+    }
+  to: ""
+  diff: |
+    - foo(Bar)
+    - "my iip" -> IN foo

src/diff.coffee

@@ -303,12 +303,27 @@ readGraph = (contents, type, options) ->
 # TODO: support parsing up a diff from the textual output format?
 # Mostly useful if/when one can apply diff as a patch
 
+nullGraph = () ->
+  g =
+    processes: {}
+    connections: []
+  return clone g
+
+
 # diff two graphs
 exports.diff = (from, to, options) ->
   options = normalizeOptions options
 
-  f = readGraph from, options.fromFormat, options
-  t = readGraph to, options.toFormat, options
+  # Handle empty graph when in JSON format
+  f = if options.fromFormat == 'json' and from == ""
+    readGraph nullGraph(), 'object', options
+  else
+    readGraph from, options.fromFormat, options
+
+  t = if options.toFormat == 'json' and to == ""
+    readGraph nullGraph(), 'object', options
+  else
+    readGraph to, options.toFormat, options
 
   diff = calculateDiff f, t
   out = formatDiffTextual diff