Example usage in unit test.

tests/example-test.cpp

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+/* example-test.cpp
+ *
+ * Some simple examples using c-capnproto
+ *
+ * Copyright (C) 2017 Alex Helfet
+ *
+ * This software may be modified and distributed under the terms
+ * of the MIT license.  See the LICENSE file for details.
+ */
+
+#include <gtest/gtest.h>
+#include <cstdint>
+
+#include "capnp_c.h"
+#include "example.capnp.h"
+
+TEST(Examples, RoundTrip) {
+  uint8_t buf[4096];
+  ssize_t sz = 0;
+
+  const char *s = "Hello.";
+
+  {
+    // Set initial object in `g`.
+    const capn_text capn_val0 = {
+      .len = strlen(s),
+      .str = s,
+      .seg = NULL
+    };
+    struct Greeting g = {
+      .text = capn_val0,
+      .timesToSay = 17,
+    };
+
+    // Serialize `g` to `buf[0..sz-1]`.
+    struct capn c;
+    capn_init_malloc(&c);
+    capn_ptr cr = capn_root(&c);
+    struct capn_segment *cs = cr.seg;
+    Greeting_ptr gp = new_Greeting(cs);
+    write_Greeting(&g, gp);
+    int setp_ret = capn_setp(capn_root(&c), 0, gp.p);
+    ASSERT_EQ(0, setp_ret);
+    sz = capn_write_mem(&c, buf, sizeof(buf), 0 /* packed */);
+    capn_free(&c);
+  }
+
+  {
+    // Write serialized object to file system.
+    FILE *f = fopen("tests/example-test.cpp.Greeting.out", "wb");
+    ASSERT_NE(f, (void*)0);
+    fwrite(buf, 1 /* size */, sz /* count */, f);
+    int close_ret = fclose(f);
+    ASSERT_EQ(0, close_ret);
+  }
+
+  {
+    // Deserialize `buf[0..sz-1]` to `rg`.
+    struct capn rc;
+    int init_mem_ret = capn_init_mem(&rc, buf, sz, 0 /* packed */);
+    ASSERT_EQ(0, init_mem_ret);
+    Greeting_ptr rroot;
+    struct Greeting rg;
+    rroot.p = capn_getp(capn_root(&rc), 0 /* off */, 1 /* resolve */);
+    read_Greeting(&rg, rroot);
+
+    // Assert deserialized values in `rg`
+    EXPECT_EQ(rg.timesToSay, 17);
+    EXPECT_EQ(strlen(s), (uint32_t) rg.text.len);
+    EXPECT_EQ(0, strncmp(s, rg.text.str, strlen(s)));
+  }
+}