Show diagnostics for in-memory compilation failures

src/main/java/run/myCode/compiler/CompileDiagnosticListener.java

@@ -1,23 +1,88 @@
-package run.myCode.compiler;
-
-import java.util.Locale;
-
-import javax.tools.Diagnostic;
-import javax.tools.DiagnosticListener;
-import javax.tools.JavaFileObject;
-
-@SuppressWarnings("unused")
-public class CompileDiagnosticListener implements DiagnosticListener<JavaFileObject>
-{
-	@Override
-	public void report(Diagnostic<? extends JavaFileObject> diagnostic)
-	{
-		/*
-		System.out.println("Line Number->" + diagnostic.getLineNumber());
-		System.out.println("code->" + diagnostic.getCode());
-		System.out.println("Message->" + diagnostic.getMessage(Locale.ENGLISH));
-		System.out.println("Source->" + diagnostic.getSource());
-		System.out.println(" ");
-		*/
-	}
-}
+package run.myCode.compiler;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Locale;
+
+import javax.tools.Diagnostic;
+import javax.tools.DiagnosticListener;
+import javax.tools.JavaFileObject;
+
+/**
+ * Collects diagnostics reported during compilation so that callers can display
+ * meaningful error messages.
+ */
+public class CompileDiagnosticListener implements DiagnosticListener<JavaFileObject> {
+
+    private final List<Diagnostic<? extends JavaFileObject>> diagnostics = new ArrayList<>();
+
+    @Override
+    public void report(Diagnostic<? extends JavaFileObject> diagnostic) {
+        diagnostics.add(diagnostic);
+    }
+
+    /**
+     * Retrieve all diagnostics that were reported during compilation.
+     *
+     * @return a list of diagnostics
+     */
+    public List<Diagnostic<? extends JavaFileObject>> getDiagnostics() {
+        return diagnostics;
+    }
+
+    /**
+     * Format collected diagnostics into human readable messages that include the
+     * source line and a caret pointing to the error column when available.
+     *
+     * @return list of formatted diagnostic strings
+     */
+    public List<String> getFormattedDiagnostics() {
+        List<String> messages = new ArrayList<>();
+        for (Diagnostic<? extends JavaFileObject> d : diagnostics) {
+            messages.add(formatDiagnostic(d));
+        }
+        return messages;
+    }
+
+    private String formatDiagnostic(Diagnostic<? extends JavaFileObject> d) {
+        StringBuilder sb = new StringBuilder();
+        String sourceName = d.getSource() == null ? "Unknown Source"
+                : new File(d.getSource().getName()).getName();
+
+        boolean appendedSource = false;
+        try {
+            if (d.getSource() != null) {
+                CharSequence content = d.getSource().getCharContent(true);
+                String[] lines = content.toString().split("\r?\n");
+                long lineNo = d.getLineNumber();
+                if (lineNo > 0 && lineNo <= lines.length) {
+                    String line = lines[(int) lineNo - 1];
+                    sb.append(line).append(System.lineSeparator());
+                    long col = d.getColumnNumber();
+                    if (col > 0) {
+                        for (int i = 1; i < col; i++) {
+                            sb.append(' ');
+                        }
+                        sb.append('^');
+                    }
+                    sb.append(System.lineSeparator());
+                    appendedSource = true;
+                }
+            }
+        } catch (IOException e) {
+            // ignore - if we can't read the source, just return the basic message
+        }
+
+        if (!appendedSource && sb.length() > 0) {
+            sb.append(System.lineSeparator());
+        }
+
+        sb.append(sourceName).append(':').append(d.getLineNumber()).append(':')
+                .append(' ').append(d.getKind().toString().toLowerCase(Locale.ENGLISH))
+                .append(':').append(' ').append(d.getMessage(Locale.ENGLISH));
+
+        return sb.toString();
+    }
+}

src/main/java/run/myCode/compiler/JavaCodeCompiler.java

@@ -9,15 +9,14 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
-import java.util.Locale;
-import java.util.logging.Level;
-import java.util.logging.Logger;
+import java.util.Locale;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 
-import javax.tools.JavaCompiler;
-import javax.tools.JavaFileObject;
-import javax.tools.StandardJavaFileManager;
-
-import javax.tools.ToolProvider;
+import javax.tools.JavaCompiler;
+import javax.tools.JavaFileObject;
+import javax.tools.StandardJavaFileManager;
+import javax.tools.ToolProvider;
 
 public class JavaCodeCompiler {
 
@@ -117,10 +116,18 @@ public static FromMemoryClassLoader compile(Iterable<? extends JavaFileObject> f
         if (DEBUG) {
             System.out.println("Starting compilation with mem URIs");
         }
-        boolean result = task.call();
-
-        // Return the classloader containing the compiled classes
-        return classLoader;
-    }
+        boolean result = task.call();
+
+        if (!result) {
+            for (String msg : diag.getFormattedDiagnostics()) {
+                System.out.println(msg);
+                System.out.println();
+            }
+            throw new ClassNotFoundException("Compilation failed");
+        }
+
+        // Return the classloader containing the compiled classes
+        return classLoader;
+    }
 
 }

src/main/java/zss/compiler/CompileDiagnosticListener.java

@@ -1,19 +1,88 @@
-package zss.compiler;
-
-import javax.tools.Diagnostic;
-import javax.tools.DiagnosticListener;
-import javax.tools.JavaFileObject;
-
-public class CompileDiagnosticListener implements DiagnosticListener<JavaFileObject> {
-
-	@Override
-	public void report(Diagnostic<? extends JavaFileObject> diagnostic) {
-
-		// System.err.println("Line Number->" + diagnostic.getLineNumber());
-		// System.err.println("code->" + diagnostic.getCode());
-		// System.err.println("Message->" + diagnostic.getMessage(Locale.ENGLISH));
-		// System.err.println("Source->" + diagnostic.getSource());
-		// System.err.println(" ");
-
-	}
-}
+package zss.compiler;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Locale;
+
+import javax.tools.Diagnostic;
+import javax.tools.DiagnosticListener;
+import javax.tools.JavaFileObject;
+
+/**
+ * Collects diagnostics reported during compilation so that callers can display
+ * meaningful error messages.
+ */
+public class CompileDiagnosticListener implements DiagnosticListener<JavaFileObject> {
+
+    private final List<Diagnostic<? extends JavaFileObject>> diagnostics = new ArrayList<>();
+
+    @Override
+    public void report(Diagnostic<? extends JavaFileObject> diagnostic) {
+        diagnostics.add(diagnostic);
+    }
+
+    /**
+     * Retrieve all diagnostics that were reported during compilation.
+     *
+     * @return a list of diagnostics
+     */
+    public List<Diagnostic<? extends JavaFileObject>> getDiagnostics() {
+        return diagnostics;
+    }
+
+    /**
+     * Format collected diagnostics into human readable messages that include the
+     * source line and a caret pointing to the error column when available.
+     *
+     * @return list of formatted diagnostic strings
+     */
+    public List<String> getFormattedDiagnostics() {
+        List<String> messages = new ArrayList<>();
+        for (Diagnostic<? extends JavaFileObject> d : diagnostics) {
+            messages.add(formatDiagnostic(d));
+        }
+        return messages;
+    }
+
+    private String formatDiagnostic(Diagnostic<? extends JavaFileObject> d) {
+        StringBuilder sb = new StringBuilder();
+        String sourceName = d.getSource() == null ? "Unknown Source"
+                : new File(d.getSource().getName()).getName();
+
+        boolean appendedSource = false;
+        try {
+            if (d.getSource() != null) {
+                CharSequence content = d.getSource().getCharContent(true);
+                String[] lines = content.toString().split("\r?\n");
+                long lineNo = d.getLineNumber();
+                if (lineNo > 0 && lineNo <= lines.length) {
+                    String line = lines[(int) lineNo - 1];
+                    sb.append(line).append(System.lineSeparator());
+                    long col = d.getColumnNumber();
+                    if (col > 0) {
+                        for (int i = 1; i < col; i++) {
+                            sb.append(' ');
+                        }
+                        sb.append('^');
+                    }
+                    sb.append(System.lineSeparator());
+                    appendedSource = true;
+                }
+            }
+        } catch (IOException e) {
+            // ignore - if we can't read the source, just return the basic message
+        }
+
+        if (!appendedSource && sb.length() > 0) {
+            sb.append(System.lineSeparator());
+        }
+
+        sb.append(sourceName).append(':').append(d.getLineNumber()).append(':')
+                .append(' ').append(d.getKind().toString().toLowerCase(Locale.ENGLISH))
+                .append(':').append(' ').append(d.getMessage(Locale.ENGLISH));
+
+        return sb.toString();
+    }
+}

src/main/java/zss/compiler/MemoryCompiler.java

@@ -6,13 +6,13 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
-import java.util.Locale;
-
-import javax.tools.JavaCompiler;
-import javax.tools.JavaFileObject;
-import javax.tools.StandardJavaFileManager;
-
-import javax.tools.ToolProvider;
+import java.util.Locale;
+
+import javax.tools.JavaCompiler;
+import javax.tools.JavaFileObject;
+import javax.tools.StandardJavaFileManager;
+
+import javax.tools.ToolProvider;
 
 /**
  * Compiles in-memory source files into byte code using the standard JDK
@@ -60,10 +60,15 @@ public static FromMemoryClassLoader compile(Iterable<? extends JavaFileObject> f
 		Writer out = new PrintWriter(System.out);
 		JavaCompiler.CompilationTask task = compiler.getTask(out, fileManager, diag, options, null, files);
 
-		Boolean result = task.call();
-		if (result == true) {
-			return classLoader;
-		}
-		return null;
-	}
-}
+                Boolean result = task.call();
+                if (Boolean.TRUE.equals(result)) {
+                        return classLoader;
+                }
+
+                for (String msg : diag.getFormattedDiagnostics()) {
+                        System.out.println(msg);
+                        System.out.println();
+                }
+                return null;
+        }
+}

src/test/java/example/HelloFailureTest.java

@@ -0,0 +1,69 @@
+package example;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.ByteArrayOutputStream;
+
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+import com.amazonaws.services.lambda.runtime.Context;
+import com.fasterxml.jackson.databind.DeserializationFeature;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import run.myCode.CompileResponse;
+import run.myCode.Hello;
+
+/**
+ * Tests compilation failures for the Hello lambda.
+ */
+public class HelloFailureTest {
+    private Context createContext() {
+        TestContext ctx = new TestContext();
+
+        ctx.setFunctionName("HelloFunction");
+
+        return ctx;
+    }
+
+    @Test
+    public void testCompilationFailureShowsDiagnostics() {
+        CompileResponse resp = doTest("jsonDataFiles/brokenLocal.json");
+
+        assertFalse("Compiler returned no response", resp == null);
+        assertFalse("Compilation unexpectedly succeeded", resp.getSucceeded());
+        String diag = resp.getResult();
+        assertTrue("Missing source line", diag.contains("System.out.println(\"hi\")"));
+        assertTrue("Missing caret in diagnostics", diag.contains("^"));
+        assertTrue("Missing file/line in diagnostics", diag.contains("Broken.java:3"));
+
+        int lineIdx = diag.indexOf("System.out.println(\"hi\")");
+        int caretIdx = diag.indexOf("^");
+        int fileIdx = diag.indexOf("Broken.java:3");
+        assertTrue("Caret should follow source line", lineIdx >= 0 && caretIdx > lineIdx);
+        assertTrue("File info should follow caret", fileIdx > caretIdx);
+
+        System.out.println("Result: " + diag);
+    }
+
+    private CompileResponse doTest(String resourceName) {
+        Hello handler = new Hello();
+
+        System.out.println("Working Directory: " + System.getProperty("java.io.tmpdir"));
+        ObjectMapper mapper = new ObjectMapper();
+        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
+
+        ByteArrayOutputStream outContent = new ByteArrayOutputStream();
+        CompileResponse resp = null;
+
+        try (InputStream input = this.getClass().getClassLoader().getResourceAsStream(resourceName)) {
+            handler.handleRequest(input, outContent, createContext());
+            resp = mapper.readValue(outContent.toString(), CompileResponse.class);
+        }
+        catch (IOException e) {
+            throw new AssertionError(e);
+        }
+
+        return resp;
+    }
+}