Fix error handling in deno::ReadFileToString

Starts a unit test for it, and adds to mock_runtime_test.

3 files changed, 18 insertions, 1 deletions

diff --git a/deno2/BUILD.gn b/deno2/BUILD.gn
index 37b9f85c6..5cb49aaa7 100644
--- a/deno2/BUILD.gn
+++ b/deno2/BUILD.gn
@@ -17,6 +17,7 @@ executable("deno") {
 executable("mock_runtime_test") {
   testonly = true
   sources = [
+    "file_util_test.cc",
     "from_snapshot.cc",
     "mock_runtime_test.cc",
   ]
diff --git a/deno2/file_util.cc b/deno2/file_util.cc
index e2c1b3049..ece14e9b1 100644
--- a/deno2/file_util.cc
+++ b/deno2/file_util.cc
@@ -11,8 +11,11 @@ namespace deno {
 
 bool ReadFileToString(const char* fn, std::string* contents) {
   std::ifstream file(fn, std::ios::binary);
+  if (file.fail()) {
+    return false;
+  }
   contents->assign(std::istreambuf_iterator<char>{file}, {});
-  return !file.bad();
+  return !file.fail();
 }
 
 class StartupDataCppWriter {
diff --git a/deno2/file_util_test.cc b/deno2/file_util_test.cc
new file mode 100644
index 000000000..3b1c3e239
--- /dev/null
+++ b/deno2/file_util_test.cc
@@ -0,0 +1,13 @@
+// Copyright 2018 Ryan Dahl <ry@tinyclouds.org>
+// All rights reserved. MIT License.
+#include "testing/gtest/include/gtest/gtest.h"
+
+#include "file_util.h"
+
+TEST(FileUtilTest, ReadFileToStringFileNotExist) {
+  std::string output;
+  EXPECT_FALSE(deno::ReadFileToString("/should_error_out.txt", &output));
+}
+
+// TODO(ry) success unit test. Needs a tempfile or fixture.
+// TEST(FileUtilTest, ReadFileToStringSuccess) { }