Tsdk 426 create j unit tests for nylas client

build.gradle

@@ -54,7 +54,11 @@ dependencies {
     testImplementation('com.github.tomakehurst:wiremock-jre8:2.26.3')
 
     // mockito for dependency mocking
-    dependencies { testImplementation "org.mockito:mockito-core:3.+" }
+    dependencies {
+        testImplementation "org.mockito:mockito-core:3.+"
+        testImplementation 'org.mockito:mockito-inline:2.13.0'
+    }
+
 
     ///////////////////////////////////
     // Examples dependencies

src/test/java/com/nylas/ByteChannelSource.java

@@ -0,0 +1,55 @@
+package com.nylas;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.ReadableByteChannel;
+import okio.Buffer;
+import okio.Source;
+import okio.Timeout;
+
+/**
+ * Creates a Source around a ReadableByteChannel and efficiently reads data using an UnsafeCursor.
+ *
+ * <p>This is a basic example showing another use for the UnsafeCursor. Using the
+ * {@link ByteBuffer#wrap(byte[], int, int) ByteBuffer.wrap()} along with access to Buffer segments,
+ * a ReadableByteChannel can be given direct access to Buffer data without having to copy the data.
+ */
+final class ByteChannelSource implements Source {
+    private final ReadableByteChannel channel;
+    private final Timeout timeout;
+
+    private final Buffer.UnsafeCursor cursor = new Buffer.UnsafeCursor();
+
+    ByteChannelSource(ReadableByteChannel channel, Timeout timeout) {
+        this.channel = channel;
+        this.timeout = timeout;
+    }
+
+    @Override public long read(Buffer sink, long byteCount) throws IOException {
+        if (!channel.isOpen()) throw new IllegalStateException("closed");
+
+        try (Buffer.UnsafeCursor ignored = sink.readAndWriteUnsafe(cursor)) {
+            timeout.throwIfReached();
+            long oldSize = sink.size();
+            int length = (int) Math.min(8192, byteCount);
+
+            cursor.expandBuffer(length);
+            int read = channel.read(ByteBuffer.wrap(cursor.data, cursor.start, length));
+            if (read == -1) {
+                cursor.resizeBuffer(oldSize);
+                return -1;
+            } else {
+                cursor.resizeBuffer(oldSize + read);
+                return read;
+            }
+        }
+    }
+
+    @Override public Timeout timeout() {
+        return timeout;
+    }
+
+    @Override public void close() throws IOException {
+        channel.close();
+    }
+}