Nested Part exceptions should bubble up.

lib/src/main/groovy/com/jessebrault/ssg/part/GspPartRenderer.groovy

@@ -56,14 +56,13 @@ class GspPartRenderer implements PartRenderer {
                     text: text,
                     urlBuilder: new PathBasedUrlBuilder(targetPath, siteSpec.baseUrl)
             ])
-            new Tuple2<>([], result.toString())
+            new Tuple2<>(embeddedPartDiagnostics, result.toString())
         } catch (Exception e) {
-            def diagnostic = new Diagnostic(
+            new Tuple2<>(
+                    [*embeddedPartDiagnostics, new Diagnostic(
                             "An exception occurred while rendering part ${ part.path }:\n${ e }",
                             e
-            )
+                    )],
-            new Tuple2<>(
-                    [diagnostic, *embeddedPartDiagnostics],
                     ''
             )
         }

lib/src/main/groovy/com/jessebrault/ssg/specialpage/GspSpecialPageRenderer.groovy

@@ -29,8 +29,8 @@ class GspSpecialPageRenderer implements SpecialPageRenderer {
             Map globals,
             String targetPath
     ) {
-        try {
         Collection<Diagnostic> diagnostics = []
+        try {
             def result = engine.createTemplate(specialPage.text).make([
                     globals: globals,
                     logger: LoggerFactory.getLogger("SpecialPage(${ specialPage.path })"),
@@ -51,7 +51,7 @@ class GspSpecialPageRenderer implements SpecialPageRenderer {
             ])
             new Tuple2<>(diagnostics, result.toString())
         } catch (Exception e) {
-            new Tuple2<>([new Diagnostic("An exception occurred while rendering specialPage ${ specialPage.path }:\n${ e }", e)], '')
+            new Tuple2<>([*diagnostics, new Diagnostic("An exception occurred while rendering specialPage ${ specialPage.path }:\n${ e }", e)], '')
         }
     }
 

lib/src/main/groovy/com/jessebrault/ssg/template/GspTemplateRenderer.groovy

@@ -32,17 +32,14 @@ class GspTemplateRenderer implements TemplateRenderer {
             Map globals,
             String targetPath
     ) {
+        def diagnostics = []
         try {
-            Collection<Diagnostic> diagnostics = []
+            def embeddableText = new EmbeddableText(text, globals, diagnostics.&addAll)
-            def onDiagnostics = { Collection<Diagnostic> partDiagnostics ->
-                diagnostics.addAll(partDiagnostics)
-            }
-            def embeddableText = new EmbeddableText(text, globals, onDiagnostics)
             def result = engine.createTemplate(template.text).make([
                     frontMatter: frontMatter,
                     globals: globals,
                     logger: LoggerFactory.getLogger("Template(${ template.path })"),
-                    parts: new EmbeddablePartsMap(parts, siteSpec, globals, onDiagnostics, embeddableText, text.path, targetPath),
+                    parts: new EmbeddablePartsMap(parts, siteSpec, globals, diagnostics.&addAll, embeddableText, text.path, targetPath),
                     path: text.path,
                     siteSpec: siteSpec,
                     tagBuilder: new DynamicTagBuilder(),
@@ -52,7 +49,7 @@ class GspTemplateRenderer implements TemplateRenderer {
             ])
             new Tuple2<>(diagnostics, result.toString())
         } catch (Exception e) {
-            new Tuple2<>([new Diagnostic("An exception occurred while rendering Template ${ template.path }:\n${ e }", e)], '')
+            new Tuple2<>([*diagnostics, new Diagnostic("An exception occurred while rendering Template ${ template.path }:\n${ e }", e)], '')
         }
     }
 

lib/src/test/groovy/com/jessebrault/ssg/part/GspPartRendererTests.groovy

@@ -10,10 +10,12 @@ import org.mockito.junit.jupiter.MockitoExtension
 import org.slf4j.Logger
 import org.slf4j.LoggerFactory
 
+import static com.jessebrault.ssg.testutil.DiagnosticsUtil.assertDiagnosticException
 import static com.jessebrault.ssg.testutil.DiagnosticsUtil.assertEmptyDiagnostics
 import static com.jessebrault.ssg.testutil.DiagnosticsUtil.getDiagnosticsMessageSupplier
 import static com.jessebrault.ssg.text.TextMocks.renderableText
 import static org.junit.jupiter.api.Assertions.assertEquals
+import static org.junit.jupiter.api.Assertions.assertInstanceOf
 import static org.junit.jupiter.api.Assertions.assertTrue
 import static org.mockito.ArgumentMatchers.anyString
 import static org.mockito.Mockito.mockStatic
@@ -219,4 +221,54 @@ class GspPartRendererTests {
         }
     }
 
+    @Test
+    void nestedPartDiagnosticBubblesUp() {
+        def nestedProblemPart = new Part(
+                'nestedProblem.gsp',
+                new PartType([], this.renderer),
+                '<% throw new RuntimeException() %>'
+        )
+        def callerPart = new Part('caller.gsp', null, '<% parts["nestedProblem.gsp"].render() %>')
+        def r = this.renderer.render(
+                callerPart,
+                [:],
+                new SiteSpec('', ''),
+                [:],
+                null,
+                [callerPart, nestedProblemPart],
+                '',
+                ''
+        )
+        assertEquals(1, r.v1.size())
+        assertDiagnosticException(RuntimeException, r.v1[0])
+        assertEquals('', r.v2)
+    }
+
+    @Test
+    void nestedPartIsBlankWhenThrowingExceptionButCallerRendered() {
+        def nestedProblemPart = new Part(
+                'nestedProblem.gsp',
+                new PartType([], this.renderer),
+                '<% throw new RuntimeException() %>'
+        )
+        def callerPart = new Part(
+                'caller.gsp',
+                null,
+                'Hello, World!<% parts["nestedProblem.gsp"].render() %>'
+        )
+        def r = this.renderer.render(
+                callerPart,
+                [:],
+                new SiteSpec('', ''),
+                [:],
+                null,
+                [callerPart, nestedProblemPart],
+                '',
+                ''
+        )
+        assertEquals(1, r.v1.size())
+        assertDiagnosticException(RuntimeException, r.v1[0])
+        assertEquals('Hello, World!', r.v2)
+    }
+
 }

lib/src/testFixtures/groovy/com/jessebrault/ssg/testutil/DiagnosticsUtil.groovy

@@ -1,7 +1,9 @@
 package com.jessebrault.ssg.testutil
 
 import com.jessebrault.ssg.Diagnostic
+import com.jessebrault.ssg.text.ExcerptGetter
 
+import static org.junit.jupiter.api.Assertions.assertInstanceOf
 import static org.junit.jupiter.api.Assertions.assertTrue
 
 class DiagnosticsUtil {
@@ -21,4 +23,10 @@ class DiagnosticsUtil {
         assertTrue(result.v1.isEmpty(), getDiagnosticsMessageSupplier(result.v1))
     }
 
+    static void assertDiagnosticException(Class<? extends Exception> expectedException, Diagnostic diagnostic) {
+        assertInstanceOf(expectedException, diagnostic.exception, {
+            "Incorrect diagnostic exception class; message: ${ diagnostic.message }"
+        })
+    }
+
 }