diff --git a/sf-writer/test/test_JFH5Writer.cpp b/sf-writer/test/test_JFH5Writer.cpp
index 838fc05..6577f3c 100644
--- a/sf-writer/test/test_JFH5Writer.cpp
+++ b/sf-writer/test/test_JFH5Writer.cpp
@@ -3,6 +3,7 @@
 #include "JFH5Writer.hpp"
 #include "gtest/gtest.h"
 #include "bitshuffle/bitshuffle.h"
+#include "mock/data.hpp"
 
 using namespace std;
 using namespace buffer_config;
@@ -31,44 +32,19 @@ TEST(JFH5Writer, test_writing)
     uint64_t stop_pulse_id = 10;
     auto n_images = stop_pulse_id - start_pulse_id + 1;
 
-    auto metadata = make_shared<ImageMetadataBlock>();
-    metadata->block_start_pulse_id = 0;
-    metadata->block_stop_pulse_id = BUFFER_BLOCK_SIZE - 1;
-
-    for (uint64_t pulse_id=start_pulse_id;
-         pulse_id<=stop_pulse_id;
-         pulse_id++) {
-
-        metadata->pulse_id[pulse_id] = pulse_id;
-        metadata->frame_index[pulse_id] = pulse_id + 10;
-        metadata->daq_rec[pulse_id] = pulse_id + 100;
-        metadata->is_good_image[pulse_id] = 1;
-    }
-
-    auto image_buffer = make_unique<uint16_t[]>(
-            MODULE_N_PIXELS * n_modules * BUFFER_BLOCK_SIZE);
-
-    for (int i_block=0; i_block<=BUFFER_BLOCK_SIZE; i_block++) {
-        for (int i_module=0; i_module<n_modules; i_module++) {
-            auto offset = i_block * MODULE_N_PIXELS;
-            offset += i_module * MODULE_N_PIXELS;
-
-            for (int i_pixel=0; i_pixel<MODULE_N_PIXELS; i_pixel++) {
-                image_buffer[offset + i_pixel] = i_pixel % 100;
-            }
-        }
-    }
+    auto meta = get_test_block_metadata(start_pulse_id, stop_pulse_id, 1);
+    auto data = get_test_block_data(n_modules);
 
     // The writer closes the file on destruction.
     {
         JFH5Writer writer(
                 "ignore.h5", n_modules, start_pulse_id, stop_pulse_id, 1);
-        writer.write(metadata.get(), (char*)(&image_buffer[0]));
+        writer.write(meta.get(), (char*)(&data[0]));
     }
 
     H5::H5File reader("ignore.h5", H5F_ACC_RDONLY);
     auto image_dataset = reader.openDataSet("image");
-    image_dataset.read(&image_buffer[0], H5::PredType::NATIVE_UINT16);
+    image_dataset.read(&data[0], H5::PredType::NATIVE_UINT16);
 
     for (int i_image=0; i_image < n_images; i_image++) {
         for (int i_module=0; i_module<n_modules; i_module++) {
@@ -77,7 +53,7 @@ TEST(JFH5Writer, test_writing)
             offset += i_module * MODULE_N_PIXELS;
 
             for (int i_pixel=0; i_pixel<MODULE_N_PIXELS; i_pixel++) {
-                ASSERT_EQ(image_buffer[offset + i_pixel], i_pixel % 100);
+                ASSERT_EQ(data[offset + i_pixel], i_pixel % 100);
             }
         }
     }
@@ -125,20 +101,12 @@ TEST(JFH5Writer, test_step_pulse_id)
     // No pulses in given range with step = 10
     ASSERT_THROW(JFH5Writer writer("ignore.h5", 1, 1, 9, 10), runtime_error);
 
-    // Stop pulse id is divisible by step.
-    ASSERT_NO_THROW(JFH5Writer writer("ignore.h5", 1, 5, 10, 10));
+    // Stop pulse id is divisible by step, but start is not.
+    ASSERT_THROW(JFH5Writer writer("ignore.h5", 1, 5, 10, 10), runtime_error);
 
-    // Start pulse id is divisible by step.
-    ASSERT_NO_THROW(JFH5Writer writer("ignore.h5", 1, 10, 19, 10));
-}
+    // Start pulse id is divisible by step, but stop is not.
+    ASSERT_THROW(JFH5Writer writer("ignore.h5", 1, 10, 19, 10), runtime_error);
 
-TEST(JFH5Writer, test_writing_with_step)
-{
-    // TODO: Implement this test.
-}
-
-TEST(JFH5Writer, test_exceptions)
-{
     // Should be ok.
     ASSERT_NO_THROW(JFH5Writer("ignore.h5", 1, 1234, 1234, 1));
     // Should be ok.
@@ -154,4 +122,67 @@ TEST(JFH5Writer, test_exceptions)
     ASSERT_THROW(JFH5Writer("ignore.h5", 1, 10, 10, 4), runtime_error);
     // stop not divisible by step
     ASSERT_THROW(JFH5Writer("ignore.h5", 1, 8, 10, 4), runtime_error);
-}
\ No newline at end of file
+}
+
+TEST(JFH5Writer, test_writing_with_step)
+{
+    size_t n_modules = 2;
+    uint64_t start_pulse_id = 500;
+    uint64_t stop_pulse_id = 599;
+    auto n_images = stop_pulse_id - start_pulse_id + 1;
+    // 50Hz test.
+    int step = 2;
+
+    auto meta = get_test_block_metadata(start_pulse_id, stop_pulse_id, step);
+    auto data = get_test_block_data(n_modules);
+
+    // The writer closes the file on destruction.
+    {
+        JFH5Writer writer(
+                "ignore.h5", n_modules, start_pulse_id, stop_pulse_id, 1);
+        writer.write(meta.get(), (char*)(&data[0]));
+    }
+
+    H5::H5File reader("ignore.h5", H5F_ACC_RDONLY);
+    auto image_dataset = reader.openDataSet("image");
+    image_dataset.read(&data[0], H5::PredType::NATIVE_UINT16);
+
+    for (int i_image=0; i_image < n_images; i_image++) {
+        for (int i_module=0; i_module<n_modules; i_module++) {
+
+            auto offset = i_image * MODULE_N_PIXELS;
+            offset += i_module * MODULE_N_PIXELS;
+
+            for (int i_pixel=0; i_pixel<MODULE_N_PIXELS; i_pixel++) {
+                ASSERT_EQ(data[offset + i_pixel], i_pixel % 100);
+            }
+        }
+    }
+
+    auto pulse_id_data = make_unique<uint64_t[]>(n_images);
+    auto pulse_id_dataset = reader.openDataSet("pulse_id");
+    pulse_id_dataset.read(&pulse_id_data[0], H5::PredType::NATIVE_UINT64);
+
+    auto frame_index_data = make_unique<uint64_t[]>(n_images);
+    auto frame_index_dataset = reader.openDataSet("frame_index");
+    frame_index_dataset.read(&frame_index_data[0], H5::PredType::NATIVE_UINT64);
+
+    auto daq_rec_data = make_unique<uint32_t[]>(n_images);
+    auto daq_rec_dataset = reader.openDataSet("daq_rec");
+    daq_rec_dataset.read(&daq_rec_data[0], H5::PredType::NATIVE_UINT32);
+
+    auto is_good_frame_data = make_unique<uint8_t[]>(n_images);
+    auto is_good_frame_dataset = reader.openDataSet("is_good_frame");
+    is_good_frame_dataset.read(
+            &is_good_frame_data[0], H5::PredType::NATIVE_UINT8);
+
+    for (uint64_t pulse_id=start_pulse_id;
+         pulse_id<=stop_pulse_id;
+         pulse_id++) {
+
+        ASSERT_EQ(pulse_id_data[pulse_id - start_pulse_id], pulse_id);
+        ASSERT_EQ(frame_index_data[pulse_id - start_pulse_id], pulse_id + 10);
+        ASSERT_EQ(daq_rec_data[pulse_id - start_pulse_id], pulse_id + 100);
+        ASSERT_EQ(is_good_frame_data[pulse_id - start_pulse_id], 1);
+    }
+}