Attempt to fix a flaky test

Add more documentation.

Affects: #70

com.io7m.laurel.documentation/src/main/resources/com/io7m/laurel/documentation/i-images.xml

@@ -4,6 +4,14 @@
          id="405b6ebe-a489-4849-8b02-57129078ab7e"
          title="Images">
   <Paragraph>
-    Images...
+    An <Term type="term">image</Term> is a rectangular array of pixels. The application does not do any special
+    processing of images beyond storing them in the dataset. Images are, in practice, expected to be in one of the
+    various popular image formats such as
+    <LinkExternal target="https://www.w3.org/TR/png-3/">PNG</LinkExternal>.
+  </Paragraph>
+  <Paragraph>
+    Each image in the dataset may have zero or more
+    <Link target="605e7b9d-a54f-4c3c-914c-c6978d2d50f7">captions</Link>
+    assigned.
   </Paragraph>
 </Section>

com.io7m.laurel.tests/src/main/java/com/io7m/laurel/tests/LFileModelExportTest.java

@@ -19,6 +19,8 @@
 
 import com.io7m.laurel.filemodel.LExportRequest;
 import com.io7m.laurel.filemodel.LFileModelEventType;
+import com.io7m.laurel.filemodel.LFileModelStatusIdle;
+import com.io7m.laurel.filemodel.LFileModelStatusLoading;
 import com.io7m.laurel.filemodel.LFileModels;
 import com.io7m.laurel.filemodel.internal.LCaptionFiles;
 import com.io7m.laurel.gui.internal.LPerpetualSubscriber;
@@ -38,7 +40,9 @@
 import java.nio.file.Path;
 import java.util.HashMap;
 import java.util.List;
+import java.util.Objects;
 import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 import java.util.zip.ZipInputStream;
 
@@ -86,7 +90,16 @@ public void testExportDatasetGood()
     }
 
     try (var model = LFileModels.open(this.outputFile, false)) {
-      Thread.sleep(1_000L);
+      final var loadLatch = new CountDownLatch(1);
+
+      model.status().subscribe((oldValue, newValue) -> {
+        if (oldValue instanceof LFileModelStatusLoading && newValue instanceof LFileModelStatusIdle) {
+          loadLatch.countDown();
+        }
+      });
+
+      loadLatch.await();
+      assertEquals(new LFileModelStatusIdle(), model.status().get());
 
       model.export(
           new LExportRequest(outputPath, true))