Support any length of stdout/stderr in test subprocess

1 files changed, 35 insertions, 8 deletions

diff --git a/src/test/java/org/zwobble/hobgoblin/compiler/testing/TestProcessRunner.java b/src/test/java/org/zwobble/hobgoblin/compiler/testing/TestProcessRunner.java
index f4074f8..ba234d5 100644
--- a/src/test/java/org/zwobble/hobgoblin/compiler/testing/TestProcessRunner.java
+++ b/src/test/java/org/zwobble/hobgoblin/compiler/testing/TestProcessRunner.java
@@ -1,10 +1,10 @@
 package org.zwobble.hobgoblin.compiler.testing;
 
 import java.io.IOException;
+import java.io.Reader;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Path;
 import java.util.List;
-import java.util.stream.Collectors;
 
 public class TestProcessRunner {
     public static TestProcessRunner command(List<String> command) {
@@ -30,16 +30,43 @@ public class TestProcessRunner {
     public ExecutionResult runCaptureOutput() throws IOException, InterruptedException {
         var process = this.processBuilder.start();
 
+        var stdout = ThreadReader.start(process.inputReader(StandardCharsets.UTF_8));
+        var stderr = ThreadReader.start(process.errorReader(StandardCharsets.UTF_8));
         var exitCode = process.waitFor();
 
-        try (
-            var stdoutReader = process.inputReader(StandardCharsets.UTF_8);
-            var stderrReader = process.errorReader(StandardCharsets.UTF_8)
-        ) {
-            var stdout = stdoutReader.lines().collect(Collectors.joining("\n"));
-            var stderr = stderrReader.lines().collect(Collectors.joining("\n"));
+        return new ExecutionResult(exitCode, stdout.waitForString(), stderr.waitForString());
+    }
+
+    private static class ThreadReader {
+        public static ThreadReader start(Reader reader) {
+            var lock = new Object();
+            var output = new String[1];
+            Thread.startVirtualThread(() -> {
+                synchronized (lock) {
+                    try (reader) {
+                        output[0] = reader.readAllAsString();
+                    } catch (IOException exception) {
+                        // TODO: handle this more elegantly.
+                        throw new RuntimeException(exception);
+                    }
+                }
+            });
+
+            return new ThreadReader(lock, output);
+        }
+
+        private final Object lock;
+        private final String[] output;
+
+        public ThreadReader(Object lock, String[] output) {
+            this.lock = lock;
+            this.output = output;
+        }
 
-            return new ExecutionResult(exitCode, stdout, stderr);
+        public String waitForString() {
+            synchronized (this.lock) {
+                return this.output[0];
+            }
         }
     }
 }