diff --git a/test/value_test.ts b/test/value_test.ts
new file mode 100644
index 0000000..414c132
--- /dev/null
+++ b/test/value_test.ts
@@ -0,0 +1,41 @@
+import {Thyme} from '/mod.ts';
+
+import {assert, assertEquals, assertStringIncludes} from 'std/testing/asserts.ts';
+
+Deno.test('constructor consistency', () => {
+  const margin = 1; // leave room for possible time differences.
+
+  const date = new Date();
+  const thyme1 = new Thyme();
+  const thyme2 = new Thyme(date);
+  const thyme3 = new Thyme(Date.now());
+
+  assert(Math.abs(+thyme1 - +thyme2) <= margin);
+  assert(Math.abs(+thyme2 - +thyme3) <= margin);
+  assert(Math.abs(+thyme1 - +thyme3) <= margin);
+});
+
+Deno.test('formatSimple', () => {
+  const moonLanding = new Thyme(Date.UTC(1969, 6, 20, 0, 20, 18));
+  assertEquals(
+    moonLanding.formatSimple('YYYY-MM-DD @ hh:mm:ss.iii'),
+    '1969-07-20 @ 00:20:18.000'
+  );
+  assertEquals(
+    moonLanding.formatSimple('Y;M;D;h;m;s;i;E;C'),
+    '69;7;20;0;20;18;0;CE;AD'
+  );
+  assertEquals(moonLanding.formatSimple(''), '');
+  assertEquals(moonLanding.formatSimple('CCCC'), 'AD  ');
+  for (const key of [...'YMDhmsiCE']) {
+    // Repeating a key X times, must result in a string with length >= X.
+    // We only need to check for equality here because 100 is very large.
+    assertEquals(moonLanding.formatSimple(key.repeat(100)).length, 100);
+  }
+});
+
+Deno.test('custom inspect', () => {
+  const test = 123456789;
+  const thyme = new Thyme(test);
+  assertStringIncludes(Deno.inspect(thyme), test.toString());
+});