diff --git a/programs/tests/t_write_read.c b/programs/tests/t_write_read.c
index 1826d7a..c13b0e9 100644
--- a/programs/tests/t_write_read.c
+++ b/programs/tests/t_write_read.c
@@ -10,116 +10,165 @@
 #include <string.h>
 #include <sys/stat.h>
 #include <sys/unistd.h>
+#include <math.h>
+#include <io/debug.h>
 
-int test_write_read()
+int create_file(const char *filename, mode_t mode)
 {
-    char *filename  = "t_write_read_file";
-    mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP;
-
     int fd = creat(filename, mode);
     if (fd < 0) {
-        printf("Failed to open file %s: %s\n", filename, strerror(errno));
-        return 1;
-    }
-
-    if (write(fd, "foo", 3) != 3) {
-        printf("First write to %s failed: %s\n", filename, strerror(errno));
-        return 1;
-    }
-
-    if (write(fd, "bar", 3) != 3) {
-        printf("Second write to %s failed: %s\n", filename, strerror(errno));
-        return 1;
-    }
-
-    close(fd);
-
-    fd = open(filename, O_RDONLY, 0);
-    if (fd < 0) {
-        printf("Failed to open file %s: %s\n", filename, strerror(errno));
-        return 1;
-    }
-
-    ssize_t bytes_read;
-    char buf[7];
-    buf[6] = 0;
-    if ((bytes_read = read(fd, &buf, 6)) < 0) {
-        printf("Reading from file %s failed: %s\n", filename, strerror(errno));
-        return 1;
+        printf("Failed to create file %s: %s\n", filename, strerror(errno));
+        return EXIT_FAILURE;
     }
     close(fd);
-
-    if (strcmp(buf, "foobar") != 0) {
-        printf("Unexpected file content: %s\n", buf);
-        return 1;
-    }
-
-    unlink(filename);
-    return 0;
+    return EXIT_SUCCESS;
 }
 
-int test_truncate()
+int check_content(const char *filename, const char *content, int length)
 {
-    char *filename = "test.txt";
-    mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP;
-    char buffer[7];
-    ssize_t bytes_read;
-    int fd;
+    pr_notice("Check content(%s, %s, %d)\n", filename, content, length);
 
-    // Create the file.
-    fd = creat(filename, mode);
+    char buffer[256];
+    memset(buffer, 0, 256);
+    // Open the file.
+    int fd = open(filename, O_RDONLY, 0);
     if (fd < 0) {
         printf("Failed to open file %s: %s\n", filename, strerror(errno));
-        return 1;
+        return EXIT_FAILURE;
     }
-    if (write(fd, "foobar", 6) != 6) {
-        printf("First write to %s failed: %s\n", filename, strerror(errno));
-        return 1;
+    // Read the content.
+    if (read(fd, &buffer, max(min(length, 256), 0)) < 0) {
+        printf("Reading from file %s failed: %s\n", filename, strerror(errno));
+        close(fd);
+        return EXIT_FAILURE;
+    }
+    if (strcmp(buffer, content) != 0) {
+        printf("Unexpected file content `%s`, expecting `%s`.\n", buffer, content);
+        close(fd);
+        return EXIT_FAILURE;
+    }
+    return EXIT_SUCCESS;
+}
+
+int write_content(const char *filename, const char *content, int length, int truncate, int append)
+{
+    pr_notice("Write content(%s, %s, %d, TRUNC: %d, APP: %d)\n", filename, content, length, truncate, append);
+
+    int flags = O_WRONLY | (truncate ? O_TRUNC : append ? O_APPEND :
+                                                          0);
+    // Open the file.
+    int fd = open(filename, flags, 0);
+    if (fd < 0) {
+        printf("Failed to open file %s: %s\n", filename, strerror(errno));
+        return EXIT_FAILURE;
+    }
+    // Read the content.
+    if (write(fd, content, length) < 0) {
+        printf("Writing on file %s failed: %s\n", filename, strerror(errno));
+        close(fd);
+        return EXIT_FAILURE;
     }
     close(fd);
+    return EXIT_SUCCESS;
+}
 
-    // Override the content.
-    fd = open(filename, O_RDWR | O_TRUNC, 0);
+int test_write_read(const char *filename)
+{
+    char buf[7] = { 0 };
+    // Create the file.
+    if (create_file(filename, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP)) {
+        return EXIT_FAILURE;
+    }
+    // Open the file.
+    int fd = open(filename, O_WRONLY, 0);
     if (fd < 0) {
         printf("Failed to open file %s: %s\n", filename, strerror(errno));
-        return 1;
+        return EXIT_FAILURE;
+    }
+    if (write(fd, "foo", 3) != 3) {
+        printf("First write to %s failed: %s\n", filename, strerror(errno));
+        close(fd);
+        return EXIT_FAILURE;
     }
     if (write(fd, "bar", 3) != 3) {
-        printf("Overriding the content of %s failed: %s\n", filename, strerror(errno));
-        return 1;
-    }
-    // Go back to the beginning.
-    lseek(fd, 0, SEEK_SET);
-    // Read the content.
-    if ((bytes_read = read(fd, &buffer, 6)) < 0) {
-        printf("Reading from file %s failed: %s\n", filename, strerror(errno));
-        return 1;
+        printf("Second write to %s failed: %s\n", filename, strerror(errno));
+        close(fd);
+        return EXIT_FAILURE;
     }
     // Close the file.
     close(fd);
-
-    printf("We found `%s`\n", buffer);
-
-    if (strcmp(buffer, "bar") != 0) {
-        printf("Unexpected file content: %s\n", buffer);
-        return 1;
+    // Check the content.
+    if (check_content(filename, "foobar", 6)) {
+        return EXIT_FAILURE;
     }
+    return EXIT_SUCCESS;
+}
 
-    // Delete the file.
-    unlink(filename);
-    return 0;
+int test_truncate(const char *filename)
+{
+    if (create_file(filename, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP)) {
+        return EXIT_FAILURE;
+    }
+    if (write_content(filename, "foobar", 6, 0, 0)) {
+        return EXIT_FAILURE;
+    }
+    if (check_content(filename, "foobar", 6)) {
+        return EXIT_FAILURE;
+    }
+    if (write_content(filename, "bark", 4, 0, 0)) {
+        return EXIT_FAILURE;
+    }
+    if (check_content(filename, "barkar", 6)) {
+        return EXIT_FAILURE;
+    }
+    if (write_content(filename, "barf", 4, 1, 0)) {
+        return EXIT_FAILURE;
+    }
+    if (check_content(filename, "barf", 6)) {
+        return EXIT_FAILURE;
+    }
+    return EXIT_SUCCESS;
+}
+
+int test_append(const char *filename)
+{
+    if (create_file(filename, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP)) {
+        return EXIT_FAILURE;
+    }
+    if (write_content(filename, "fusro", 5, 0, 0)) {
+        return EXIT_FAILURE;
+    }
+    if (write_content(filename, "dah", 3, 0, 1)) {
+        return EXIT_FAILURE;
+    }
+    if (check_content(filename, "fusrodah", 8)) {
+        return EXIT_FAILURE;
+    }
+    return EXIT_SUCCESS;
 }
 
 int main(int argc, char *argv[])
 {
-    printf("Running `test_write_read`...\n");
-    if (test_write_read()) {
-        exit(EXIT_FAILURE);
-    }
-    printf("Running `test_truncate`...\n");
-    if (test_truncate()) {
-        exit(EXIT_FAILURE);
-    }
+    char *filename = "test.txt";
 
+    // printf("Running `test_write_read`...\n");
+    // if (test_write_read(filename)) {
+    //     unlink(filename);
+    //     return EXIT_FAILURE;
+    // }
+    // unlink(filename);
+
+    printf("Running `test_truncate`...\n");
+    if (test_truncate(filename)) {
+        unlink(filename);
+        return EXIT_FAILURE;
+    }
+    unlink(filename);
+
+    printf("Running `test_append`...\n");
+    if (test_append(filename)) {
+        unlink(filename);
+        return EXIT_FAILURE;
+    }
     return EXIT_SUCCESS;
 }