Report error when import can't be resolved

moor_generator/lib/src/analyzer/runner/task.dart

@@ -89,14 +89,16 @@ class Task {
             continue;
           }
 
-          final found = session.resolve(file, import.importedFile);
-          if (!await backend.exists(found.uri)) {
+          final found = await _resolveOrReportError(file, import.importedFile,
+              (errorMsg) {
             step.reportError(ErrorInMoorFile(
               span: import.importString.span,
               severity: Severity.error,
-              message: 'File does not exist: ${import.importedFile}',
+              message: errorMsg,
             ));
-          } else {
+          });
+
+          if (found != null) {
             resolvedImports.add(found);
             parsed.resolvedImports[import] = found;
           }
@@ -123,14 +125,14 @@ class Task {
           final resolvedForAccessor = <FoundFile>[];
 
           for (final import in accessor.declaredIncludes) {
-            final found = session.resolve(file, import);
-            if (!await backend.exists(found.uri)) {
+            final found = await _resolveOrReportError(file, import, (errorMsg) {
               step.reportError(ErrorInDartCode(
                 affectedElement: accessor.fromClass,
                 severity: Severity.error,
-                message: 'Include could not be resolved: $import',
+                message: errorMsg,
               ));
-            } else {
+            });
+            if (found != null) {
               resolvedImports.add(found);
               resolvedForAccessor.add(found);
             }
@@ -150,6 +152,24 @@ class Task {
     return createdStep;
   }
 
+  Future<FoundFile> _resolveOrReportError(
+    FoundFile file,
+    String import,
+    void Function(String) reporter,
+  ) async {
+    final found = session.resolve(file, import);
+
+    if (found == null) {
+      reporter('Invalid import: $import');
+    } else if (!await backend.exists(found.uri)) {
+      reporter('Imported file does not exist: $import');
+    } else {
+      return found;
+    }
+
+    return null;
+  }
+
   /// Crawls through all (transitive) imports of the provided [roots]. Each
   /// [FoundFile] in the iterable provides queries and tables that are available
   /// to the entity that imports them.

moor_generator/lib/src/analyzer/session.dart

@@ -55,9 +55,13 @@ class MoorSession {
 
   /// Resolves an import directive in the context of the [source] file. This
   /// can handle both relative imports and `package:` imports.
+  ///
+  /// Returns null if the import could not be resolved. Note that it does not
+  /// return null if the file doesn't exists - that needs to be checked
+  /// separately.
   FoundFile resolve(FoundFile source, String import) {
     final resolvedUri = backend.resolve(source.uri, import);
-    return _uriToFile(resolvedUri);
+    return resolvedUri == null ? null : _uriToFile(resolvedUri);
   }
 
   /// Registers a file by its absolute uri.

moor_generator/lib/src/backends/backend.dart

@@ -9,6 +9,8 @@ import 'package:logging/logging.dart';
 abstract class Backend {
   /// Resolves an [import] statement from the context of a [base] uri. This
   /// should support both relative and `package:` imports.
+  ///
+  /// Returns null if the url can't be resolved.
   Uri resolve(Uri base, String import);
 }
 

moor_generator/lib/src/backends/common/backend.dart

@@ -12,7 +12,10 @@ class CommonBackend extends Backend {
 
   @override
   Uri resolve(Uri base, String import) {
-    return Uri.parse(driver.absolutePath(Uri.parse(import), base: base));
+    final absolute = driver.absolutePath(Uri.parse(import), base: base);
+    if (absolute == null) return null;
+
+    return Uri.parse(absolute);
   }
 }
 

moor_generator/lib/src/backends/common/driver.dart

@@ -133,12 +133,13 @@ class MoorDriver implements AnalysisDriverGeneric {
   /// Finds the absolute path of a [reference] url, optionally assuming that the
   /// [reference] appears in [base]. This supports both "package:"-based uris
   /// and relative imports.
+  /// Returns null if the uri can't be parsed.
   String absolutePath(Uri reference, {Uri base}) {
     final factory = dartDriver.sourceFactory;
     final baseSource = base == null ? null : factory.forUri2(base);
 
     final source = factory.resolveUri(baseSource, reference.toString());
-    return source.fullName;
+    return source?.fullName;
   }
 
   CommonTask _createTask(Uri uri) {

moor_generator/test/analyzer/runner/task_test.dart

@@ -0,0 +1,51 @@
+import 'package:moor_generator/src/analyzer/errors.dart';
+import 'package:test/test.dart';
+
+import '../utils.dart';
+
+void main() {
+  group("reports error when an import can't be found", () {
+    test('in moor file', () async {
+      final state = TestState.withContent({
+        'foo|lib/a.moor': '''
+import 'b.moor';
+        ''',
+      });
+
+      final result = await state.analyze('package:foo/a.moor');
+
+      expect(
+        result.errors.errors,
+        contains(const TypeMatcher<ErrorInMoorFile>().having(
+          (e) => e.message,
+          'message',
+          allOf(contains('b.moor'), contains('file does not exist')),
+        )),
+      );
+    });
+
+    test('in a dart file', () async {
+      final state = TestState.withContent({
+        'foo|lib/a.dart': '''
+import 'package:moor/moor.dart';        
+
+@UseMoor(include: {'b.moor'})
+class Database {
+
+}        
+            ''',
+      });
+
+      final result = await state.analyze('package:foo/a.dart');
+
+      expect(
+        result.errors.errors,
+        contains(const TypeMatcher<ErrorInDartCode>().having(
+          (e) => e.message,
+          'message',
+          allOf(contains('b.moor'), contains('file does not exist')),
+        )),
+      );
+    });
+  });
+}