[io-279] fixing macos-x-13-java8 unstable test due to posix file time resolution is only 1s. Adding TestUtils.sleepTillNextFullSecond() (#760)

Author: JoergBudi

src/test/java/org/apache/commons/io/input/TailerTest.java

@@ -724,21 +724,31 @@ void testTailerIgnoreTouch() throws Exception {
 
             // Write some lines to the file
             writeLines(file, "Line one");
-            final long testDelayMillis = delayMillis * 10;
-            TestUtils.sleep(testDelayMillis);
-            List<String> lines = listener.getLines();
+            List<String> lines = expectLinesWithLongTimeout(listener, delayMillis, 20);
             assertEquals(1, lines.size(), "1 line count");
             assertEquals("Line one", lines.get(0), "1 line 1");
             listener.clear();
 
             // touch the file
+            TestUtils.sleepTillNextFullSecond();  // ensure to be within the next second because of posix fs limitation
             file.setLastModified(System.currentTimeMillis());
-            TestUtils.sleep(testDelayMillis);
+            TestUtils.sleep(delayMillis * 10);
             lines = listener.getLines();
             assertEquals(0, lines.size(), "nothing should have changed by touching");
         }
     }
 
+    private List<String> expectLinesWithLongTimeout(final TestTailerListener listener, final long minDelay, int count) throws Exception {
+        for (int i = 0; i < count ; i++) {
+            TestUtils.sleep(minDelay);
+            final List<String> lines = listener.getLines();
+            if (lines.size() > 0) {
+                return lines;
+            }
+        }
+        throw new RuntimeException("waiting for TestTailerListener.getLines() timed out after " + (count * minDelay) + " ms");
+    }
+
     @Test
     void testTailerReissueOnTouch() throws Exception {
         // Create & start the Tailer
@@ -758,17 +768,15 @@ void testTailerReissueOnTouch() throws Exception {
 
             // Write some lines to the file
             writeLines(file, "Line one");
-            final long testDelayMillis = delayMillis * 10;
-            TestUtils.sleep(testDelayMillis);
-            List<String> lines = listener.getLines();
+            List<String> lines = expectLinesWithLongTimeout(listener, delayMillis, 50);
             assertEquals(1, lines.size(), "1 line count");
             assertEquals("Line one", lines.get(0), "1 line 1");
             listener.clear();
 
             // touch the file
+            TestUtils.sleepTillNextFullSecond(); // ensure to be within the next second because of posix fs limitation
             file.setLastModified(System.currentTimeMillis());
-            TestUtils.sleep(testDelayMillis);
-            lines = listener.getLines();
+            lines = expectLinesWithLongTimeout(listener, delayMillis, 20);
             assertEquals(1, lines.size(), "1 line count");
             assertEquals("Line one", lines.get(0), "1 line 1");
             listener.clear();

src/test/java/org/apache/commons/io/test/TestUtils.java

@@ -251,6 +251,19 @@ public static void sleep(final long millis) throws InterruptedException {
         ThreadUtils.sleep(Duration.ofMillis(millis));
     }
 
+    /**
+     * Sleeps till the next full second.
+     *
+     * This method is useful when you want to set a guaranteed newer file system timestamp.
+     * Posix file systems only guarantee one second resolution, and e.g.
+     * some mac os x filesystems only offer that.
+     *
+     * @throws InterruptedException if interrupted.
+     */
+    public static void sleepTillNextFullSecond() throws InterruptedException {
+        sleep(1001 - (System.currentTimeMillis() % 1000));
+    }
+
     /**
      * Sleeps and swallows InterruptedException.
      *