ninja windows: emulate msvs generator behaviour for msvs_error_on_missing_sources=1

test/msvs/missing_sources/gyptest-missing.py

Index: test/msvs/missing_sources/gyptest-missing.py
===================================================================
--- test/msvs/missing_sources/gyptest-missing.py	(revision 1525)
+++ test/msvs/missing_sources/gyptest-missing.py	(working copy)
@@ -11,31 +11,33 @@
 
 import TestGyp
 import os
+import sys
 
-test = TestGyp.TestGyp(formats=['msvs'], workdir='workarea_all')
+if sys.platform == 'win32':
+  test = TestGyp.TestGyp(formats=['msvs', 'ninja'], workdir='workarea_all')
 
-# With the flag not set
-test.run_gyp('hello_missing.gyp')
-
-# With the flag explicitly set to 0
-try:
-  os.environ['GYP_GENERATOR_FLAGS'] = 'msvs_error_on_missing_sources=0'
+  # With the flag not set
   test.run_gyp('hello_missing.gyp')
-finally:
-  del os.environ['GYP_GENERATOR_FLAGS']
 
-# With the flag explicitly set to 1
-try:
-  os.environ['GYP_GENERATOR_FLAGS'] = 'msvs_error_on_missing_sources=1'
-  # Test to make sure GYP raises an exception (exit status 1). Since this will
-  # also print a backtrace, ensure that TestGyp is not checking that stderr is
-  # empty by specifying None, which means do not perform any checking.
-  # Instead, stderr is checked below to ensure it contains the expected
-  # output.
-  test.run_gyp('hello_missing.gyp', status=1, stderr=None)
-finally:
-  del os.environ['GYP_GENERATOR_FLAGS']
-test.must_contain_any_line(test.stderr(),
-                           ["Missing input files:"])
+  # With the flag explicitly set to 0
+  try:
+    os.environ['GYP_GENERATOR_FLAGS'] = 'msvs_error_on_missing_sources=0'
+    test.run_gyp('hello_missing.gyp')
+  finally:
+    del os.environ['GYP_GENERATOR_FLAGS']
 
-test.pass_test()
+  # With the flag explicitly set to 1
+  try:
+    os.environ['GYP_GENERATOR_FLAGS'] = 'msvs_error_on_missing_sources=1'
+    # Test to make sure GYP raises an exception (exit status 1). Since this will
+    # also print a backtrace, ensure that TestGyp is not checking that stderr is
+    # empty by specifying None, which means do not perform any checking.
+    # Instead, stderr is checked below to ensure it contains the expected
+    # output.
+    test.run_gyp('hello_missing.gyp', status=1, stderr=None)
+  finally:
+    del os.environ['GYP_GENERATOR_FLAGS']
+  test.must_contain_any_line(test.stderr(),
+                            ["Missing input files:"])
+
+  test.pass_test()