Increase test coverage

Fixed an intermittent deadlock in MainTest:
FlushListener could receive more than the expected number of flushes
before the VirtualTerminalInteractor was given control. So by setting
the flush count to zero in waitForFlushes(), flushes could be lost. Now
it only reduces the number of flushes by the expected number.

test/acceptance/fixture/LispInterpreterFixture.java

@@ -17,7 +17,7 @@ public class LispInterpreterFixture {
     private static LispInterpreter interpreter = null;
 
     public static void buildInterpreter() {
-        LispInterpreterBuilder builder = LispInterpreterBuilderImpl.getInstance();
+        LispInterpreterBuilder builder = new LispInterpreterBuilderImpl() {};
         builder.setOutput(new PrintStream(outputStream));
         builder.setErrorOutput(new PrintStream(outputStream));
         builder.setNotInteractive();

test/main/MainTest.java

@@ -41,9 +41,12 @@ public class MainTest {
         latch = new CountDownLatch(1);
 
         new Thread(() -> {
-            LispMain main = new LispMain(new LispInterpreterBuilderImpl() {}, terminal.getConfiguration());
-            main.runInteractive();
-            latch.countDown();
+            try {
+                LispMain main = new LispMain(new LispInterpreterBuilderImpl() {}, terminal.getConfiguration());
+                main.runInteractive();
+            } finally {
+                latch.countDown();
+            }
         }).start();
 
         return terminal;
@@ -121,8 +124,11 @@ public class MainTest {
     }
 
     @Test
-    public void defaultConstructorCoverage() {
-        new LispMain();
+    public void runMain() {
+        LispMain.main(new String[] { "test/main/test-files/file.lisp" });
+
+        assertEquals("", getSystemErrLog());
+        assertEquals(format("{0}{1}{2}\n\n", ANSI_GREEN, "RADISH", ANSI_RESET), getSystemOutLog());
     }
 
 }

test/terminal/FlushListener.java

@@ -12,12 +12,12 @@ public class FlushListener implements VirtualTerminalListener {
         this.flushCount = 0;
     }
 
-    public int getFlushCount() {
+    public synchronized int getFlushCount() {
         return flushCount;
     }
 
-    public void resetFlushCount() {
-        flushCount = 0;
+    public synchronized void reduceFlushCount(int reduction) {
+        flushCount -= reduction;
     }
 
     @Override

test/terminal/VirtualTerminalInteractor.java

@@ -110,7 +110,7 @@ public class VirtualTerminalInteractor {
                 while (flushListener.getFlushCount() < flushCount)
                     flushListener.wait();
 
-                flushListener.resetFlushCount();
+                flushListener.reduceFlushCount(flushCount);
             }
         } catch (InterruptedException ignored) {}
     }