diff --git a/test/test_dstr.c b/test/test_dstr.c
new file mode 100644
index 0000000..f17b419
--- /dev/null
+++ b/test/test_dstr.c
@@ -0,0 +1,79 @@
+#include "../src/include/dstr.h"
+#include "Unity/src/unity.h"
+#include <string.h>
+
+void setUp() {};
+void tearDown() {};
+
+void test_dstr_init() {
+    Dstr* dstr = dstr_init();
+    TEST_ASSERT_EQUAL(0, strlen(dstr->buf));
+    TEST_ASSERT_EQUAL(0, dstr->ln);
+    TEST_ASSERT_EQUAL(DSTR_INITSZ, dstr->bufsz);
+}
+
+void test_dstr_append() {
+    Dstr* dstr;
+
+    // Test simple appending.
+    dstr = dstr_init();
+    char* hello_world = "Hello, world!";
+    dstr_append(dstr, hello_world, strlen(hello_world));
+
+    TEST_ASSERT_EQUAL_STRING(hello_world, dstr->buf);
+    TEST_ASSERT_EQUAL(strlen(hello_world), dstr->ln);
+    TEST_ASSERT_EQUAL(DSTR_INITSZ, dstr->bufsz);
+
+    dstr_destroy(dstr);
+
+    // Test buffer doubling.
+    dstr = dstr_init();
+
+    char h[DSTR_INITSZ + 20];
+    memset(h, 'h', DSTR_INITSZ + 19);
+    h[DSTR_INITSZ + 19] = '\0';
+    dstr_append(dstr, h, strlen(h));
+
+    TEST_ASSERT_EQUAL_STRING(h, dstr->buf);
+    TEST_ASSERT_EQUAL(strlen(h), dstr->ln);
+    TEST_ASSERT_EQUAL(DSTR_INITSZ * 2, dstr->bufsz);
+}
+
+void test_dstr_appendch() {
+    Dstr* dstr;
+
+    // Test simple character appending.
+    dstr = dstr_init();
+    char c = 'c';
+    char* c_str = "c";
+    dstr_appendch(dstr, c);
+
+    TEST_ASSERT_EQUAL_STRING(c_str, dstr->buf);
+    TEST_ASSERT_EQUAL(strlen(c_str), dstr->ln);
+    TEST_ASSERT_EQUAL(DSTR_INITSZ, dstr->bufsz);
+
+    dstr_destroy(dstr);
+
+    // Test buffer doubling.
+    dstr = dstr_init();
+
+    // Test against this string.
+    char h[DSTR_INITSZ + 20];
+    memset(h, 'h', DSTR_INITSZ + 19);
+    h[DSTR_INITSZ + 19] = '\0';
+
+    for (int i = 0; i < DSTR_INITSZ + 19; i++) dstr_appendch(dstr, 'h');
+
+    TEST_ASSERT_EQUAL_STRING(h, dstr->buf);
+    TEST_ASSERT_EQUAL(strlen(h), dstr->ln);
+    TEST_ASSERT_EQUAL(DSTR_INITSZ * 2, dstr->bufsz);
+}
+
+// not needed when using generate_test_runner.rb
+int main(void) {
+    UNITY_BEGIN();
+    RUN_TEST(test_dstr_init);
+    RUN_TEST(test_dstr_append);
+    RUN_TEST(test_dstr_appendch);
+    return UNITY_END();
+}