Adds configuration option for large file warning threshold.

spec/workspace-spec.coffee

@@ -432,31 +432,37 @@ describe "Workspace", ->
         runs ->
           expect(editor.largeFileMode).toBe true
 
-    describe "when the file is over 20MB", ->
-      it "prompts the user to make sure they want to open a file this big", ->
-        spyOn(fs, 'getSizeSync').andReturn 20 * 1048577 # 20MB
+    describe "when the file is over user-defined limit", ->
+      test = (size, shouldPrompt) ->
+        spyOn(fs, 'getSizeSync').andReturn size * 1048577
         atom.applicationDelegate.confirm.andCallFake -> selectedButtonIndex
         atom.applicationDelegate.confirm()
-        selectedButtonIndex = 1 # cancel
-
         editor = null
         waitsForPromise ->
           workspace.open('sample.js').then (e) -> editor = e
+        if shouldPrompt
+          runs ->
+            expect(editor).toBeUndefined()
+            expect(atom.applicationDelegate.confirm).toHaveBeenCalled()
 
-        runs ->
-          expect(editor).toBeUndefined()
-          expect(atom.applicationDelegate.confirm).toHaveBeenCalled()
-
-          atom.applicationDelegate.confirm.reset()
-          selectedButtonIndex = 0 # open the file
+            atom.applicationDelegate.confirm.reset()
+            selectedButtonIndex = 0 # open the file
 
-        waitsForPromise ->
-          workspace.open('sample.js').then (e) -> editor = e
+          waitsForPromise ->
+            workspace.open('sample.js').then (e) -> editor = e
 
         runs ->
           expect(atom.applicationDelegate.confirm).toHaveBeenCalled()
           expect(editor.largeFileMode).toBe true
-
+      it "prompts the user to make sure they want to open a file this big", ->
+        atom.config.set "core.warnOnLargeFileLimit", 20
+        test 20, true
+      it "doesn't prompt on files below the limit", ->
+        atom.config.set "core.warnOnLargeFileLimit", 30
+        test 20, false
+      it "prompts for smaller files with a lower limit", ->
+        atom.config.set "core.warnOnLargeFileLimit", 5
+        test 10, true
     describe "when passed a path that matches a custom opener", ->
       it "returns the resource returned by the custom opener", ->
         fooOpener = (pathToOpen, options) -> {foo: pathToOpen, options} if pathToOpen?.match(/\.foo/)

src/config-schema.coffee

@@ -122,6 +122,10 @@ module.exports =
           {value: 'no', description: 'Do not send any telemetry data'}
           {value: 'undecided', description: 'Undecided (Atom will ask again next time it is launched)'}
         ]
+      warnOnLargeFileLimit:
+        description: 'Warn before opening files larger than this number of megabytes.'
+        type: 'number'
+        default: 20
   editor:
     type: 'object'
     properties:

src/workspace.coffee

@@ -550,7 +550,7 @@ class Workspace extends Model
     fileSize = fs.getSizeSync(filePath)
 
     largeFileMode = fileSize >= 2 * 1048576 # 2MB
-    if fileSize >= 20 * 1048576 # 20MB
+    if fileSize >= @config.get('core.warnOnLargeFileLimit') * 1048576 # 20MB by default
       choice = @applicationDelegate.confirm
         message: 'Atom will be unresponsive during the loading of very large files.'
         detailedMessage: "Do you still want to load this file?"