Add exercise 1-6

chapter_1/exercise_1_6/BUILD

@@ -0,0 +1,9 @@
+cc_test(
+    name = "test",
+    size = "small",
+    srcs = ["test/test.cc"],
+    deps = [
+        "@googletest//:gtest",
+        "@googletest//:gtest_main",
+    ],
+)

chapter_1/exercise_1_6/test/test.cc

@@ -0,0 +1,23 @@
+#include <gtest/gtest.h>
+#include <limits.h>
+#include <stdio.h>
+
+TEST(Exercise_1_6, VerifyEof) {
+  int expression_result = 0;
+
+  FILE *fp = fopen("input.txt", "w");
+
+  for (int i = 0; i < SCHAR_MAX; i++) {
+    fputc(i, fp);
+  }
+
+  fclose(fp);
+
+  freopen("input.txt", "r", stdin);
+
+  while ((expression_result = getchar() != EOF)) {
+    EXPECT_EQ(1, expression_result);
+  }
+
+  EXPECT_EQ(0, expression_result);
+}