[Cronet] Fix ExperimentalOptionsTest flake

components/cronet/android/test/javatests/src/org/chromium/net/ExperimentalOptionsTest.java

Index: components/cronet/android/test/javatests/src/org/chromium/net/ExperimentalOptionsTest.java
diff --git a/components/cronet/android/test/javatests/src/org/chromium/net/ExperimentalOptionsTest.java b/components/cronet/android/test/javatests/src/org/chromium/net/ExperimentalOptionsTest.java
index cb47233dea4eebdaaa4e6d1fb7f6af3841346f68..c14a15208f46d876571a752a609c1a85a6605a6d 100644
--- a/components/cronet/android/test/javatests/src/org/chromium/net/ExperimentalOptionsTest.java
+++ b/components/cronet/android/test/javatests/src/org/chromium/net/ExperimentalOptionsTest.java
@@ -8,12 +8,14 @@ import android.support.test.filters.SmallTest;
 
 import org.json.JSONObject;
 
+import org.chromium.base.Log;
 import org.chromium.base.PathUtils;
 import org.chromium.base.test.util.Feature;
 
-import java.io.BufferedReader;
 import java.io.File;
-import java.io.FileReader;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
 
 /**
  * Tests for experimental options.
@@ -66,22 +68,12 @@ public class ExperimentalOptionsTest extends CronetTestBase {
         assertEquals(200, callback.mResponseInfo.getHttpStatusCode());
         assertEquals("GET", callback.mResponseAsString);
         mTestFramework.mCronetEngine.stopNetLog();
-        assertTrue(logfile.exists());
-        assertTrue(logfile.length() != 0);
-        BufferedReader logReader = new BufferedReader(new FileReader(logfile));
-        boolean validFile = false;
-        try {
-            String logLine;
-            while ((logLine = logReader.readLine()) != null) {
-                if (logLine.contains("HostResolverRules")) {
-                    validFile = true;
-                    break;
-                }
-            }
-        } finally {
-            logReader.close();
+        while (true) {
+            Log.i(TAG, "Still waiting for netlog file.....");
+            Thread.sleep(10000);

[kapishnikov, 2017/04/18 16:24:34]

This will increase the duration of every test run by 10 seconds. I would
suggest:
1) Check first and sleep only if the file doesn't contain the string.
2) Decrease the sleep interval from 10 seconds to 100 ms.
3) Set max waiting interval for 5 seconds and fail the test if the string is
still not in the file.

[xunjieli, 2017/04/18 18:30:29]

Done. Great idea! Per offline discussion, I have changed the while(true) to try
5 times with 100ms interval.

+            boolean contains = false;
+            if (fileContainsString(logfile, "HostResolverRules")) break;
         }
-        assertTrue(validFile);
         assertTrue(logfile.delete());
         assertTrue(!logfile.exists());
     }
@@ -107,23 +99,33 @@ public class ExperimentalOptionsTest extends CronetTestBase {
         assertEquals(200, callback.mResponseInfo.getHttpStatusCode());
         assertEquals("GET", callback.mResponseAsString);
 
-        assertTrue(file.exists());
-        assertTrue(file.length() != 0);
-        BufferedReader logReader = new BufferedReader(new FileReader(file));
-        boolean validFile = false;
-        try {
-            String logLine;
-            while ((logLine = logReader.readLine()) != null) {
-                if (logLine.contains("CLIENT_RANDOM")) {
-                    validFile = true;
-                    break;
-                }
-            }
-        } finally {
-            logReader.close();
+        while (true) {
+            Log.i(TAG, "Still waiting for ssl key log file.....");
+            Thread.sleep(10000);
+            boolean contains = false;
+            if (fileContainsString(file, "CLIENT_RANDOM")) break;
         }
-        assertTrue(validFile);
         assertTrue(file.delete());
         assertTrue(!file.exists());
     }
+
+    // Returns whether a file contains a particular string.
+    private boolean fileContainsString(File file, String content) throws IOException {
+        FileInputStream fileInputStream = null;
+        try {
+            fileInputStream = new FileInputStream(file);
+            byte[] data = new byte[(int) file.length()];
+            fileInputStream.read(data);
+            return new String(data, "UTF-8").contains(content);
+        } catch (FileNotFoundException e) {
+            // Ignored this exception since the file will only be created when updates are
+            // flushed to the disk.
+            Log.i(TAG, "file not found");
+        } finally {
+            if (fileInputStream != null) {
+                fileInputStream.close();
+            }
+        }
+        return false;
+    }
 }