Handle missing output file info in log files

This is an attempt to fix #46 (and related issues) which are caused
by "Output written on .." text missing in log files. This caused
problems due to `outputFilePath` being set to `null` yet the status code
was 0, thus the build was treated as a success, but paths ended up
with an invalid "null" segment.

Added a regression style test that should (hopefully) ensure this
problem does not get re-introduced.

lib/latex.coffee

@@ -44,27 +44,15 @@ module.exports =
     proc = builder.run args, (statusCode) =>
       @destroyProgressIndicator()
       result = builder.parseLogFile(rootFilePath)
-      switch statusCode
-        when 0
-          @pdfFile = result.outputFilePath
-          @moveResult(result, rootFilePath) if @shouldMoveResult()
-          @showResult(result)
-        when 127 then @showError \
-          """
-          TeXification failed! Builder executable not found.
-
-            latex.texPath
-              as configured: #{atom.config.get('latex.texPath')}
-              when resolved: #{builder.constructPath()}
-
-          Make sure latex.texPath is configured correctly; either adjust it \
-          via the settings view, or directly in your config.cson file.
-          """
-        else @showError \
-          """
-          TeXification failed with status code #{statusCode}! \
-          Check the log file for more info...
-          """
+
+      unless result.outputFilePath?
+        error = @constructError(statusCode, builder)
+        @showError(error)
+        return false
+
+      @pdfFile = result.outputFilePath
+      @moveResult(result, rootFilePath) if @shouldMoveResult()
+      @showResult(result)
 
     return true
 
@@ -202,3 +190,22 @@ module.exports =
   destroyErrorIndicator: ->
     @errorIndicator?.destroy()
     @errorIndicator = null
+
+  constructError: (statusCode, builder) ->
+    switch statusCode
+      when 127
+        """
+        TeXification failed! Builder executable not found.
+
+          latex.texPath
+            as configured: #{atom.config.get('latex.texPath')}
+            when resolved: #{builder.constructPath()}
+
+        Make sure latex.texPath is configured correctly; either adjust it \
+        via the settings view, or directly in your config.cson file.
+        """
+      else
+        """
+        TeXification failed with status code #{statusCode}! \
+        Check the log file for more info...
+        """

spec/latex-spec.coffee

@@ -2,6 +2,7 @@ helpers = require './spec-helpers'
 fs = require 'fs-plus'
 path = require 'path'
 latex = require '../lib/latex'
+LatexmkBuilder = require '../lib/builders/latexmk'
 
 describe "Latex", ->
   [fixturesPath] = []
@@ -119,6 +120,29 @@ describe "Latex", ->
           warnings: []
         }
 
+    it "treats missing output file data in log file as an error", ->
+      class MockBuilder extends LatexmkBuilder
+        parseLogFile: (texFilePath) ->
+          result =
+            outputFilePath: null
+            errors: []
+            warnings: []
+
+      spyOn(latex, 'getBuilder').andReturn(new MockBuilder())
+      spyOn(latex, 'showError').andCallThrough()
+
+      waitsForPromise ->
+        atom.workspace.open('file.tex')
+
+      runs ->
+        latex.build()
+
+      waitsFor ->
+        latex.showError.callCount == 1
+
+      runs ->
+        expect(latex.showError).toHaveBeenCalled()
+
   describe "getOpener", ->
     originalPlatform = process.platform