Improve test coverage for detecting wrong file mode

Author: Dmitry-Me

test/testio.cpp

@@ -251,6 +251,12 @@ class TestIO : public TestFixture {
               "}", false, false, Settings::Win32W);
         ASSERT_EQUALS("", errout.str());
 
+        check("void foo(FILE*& f) {\n"
+              "    f = tmpfile();\n"
+              "    fwrite(buffer, 5, 6, f);\n"
+              "}", false, false, Settings::Win32W);
+        ASSERT_EQUALS("", errout.str());
+
         // Write mode
         check("void foo(FILE*& f) {\n"
               "    f = fopen(name, \"w\");\n"
@@ -266,6 +272,12 @@ class TestIO : public TestFixture {
               "}");
         ASSERT_EQUALS("", errout.str());
 
+        check("void foo(FILE*& f) {\n"
+              "    f = tmpfile();\n"
+              "    fread(buffer, 5, 6, f);\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
+
         // Append mode
         check("void foo(FILE*& f) {\n"
               "    f = fopen(name, \"a\");\n"