Reverse the reversed error message #6290 (#6368)

Shows list of files not found first before listing the directories searched.
At the same time I referenced the constant for RESOURCES_FRONTEND_DEFAULT
instead of hard-coding that path.

Added two new test cases to cover single- and multi-file exception messages.

Fixes #6290

flow-server/src/main/java/com/vaadin/flow/server/frontend/TaskUpdateImports.java

@@ -31,6 +31,7 @@
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 
+import com.vaadin.flow.server.Constants;
 import org.apache.commons.io.FileUtils;
 import org.slf4j.LoggerFactory;
 
@@ -265,16 +266,17 @@ && frontendFileExists(localModulePath)) {
         }
 
         if (!resourceNotFound.isEmpty()) {
-            String prefix = String.format(
-                    "Failed to resolve the following files either:"
-                            + "%n   · in the `%s` sources folder"
-                            + "%n   · or as a `META-INF/resources/frontend` resource in some JAR.",
-                    frontendDirectory.getPath());
+            String prefix =  "Failed to find the following files: ";
             String suffix = String.format(
-                    "Please, double check that those files exist. If you use a custom directory "
+                    "%n  Locations searched were:"
+                            + "%n      - `%s` in this project"
+                            + "%n      - `%s` in included JARs"
+                            + "%n%n  Please, double check that those files exist. If you use a custom directory "
                             + "for your resource files instead of default "
                             + "`frontend` folder then make sure you it's correctly configured "
                             + "(e.g. set '%s' property)",
+                    frontendDirectory.getPath(),
+                    Constants.RESOURCES_FRONTEND_DEFAULT,
                     FrontendUtils.PARAM_FRONTEND_DIR);
             throw new IllegalStateException(
                     notFoundMessage(resourceNotFound, prefix, suffix));
@@ -313,7 +315,7 @@ private void handleImports(String path, AbstractTheme theme,
         } catch (IOException exception) {
             LoggerFactory.getLogger(TaskUpdateImports.class)
                     .warn("Could not read file {}. Skipping "
-                            + "applyig theme for its imports", file.getPath(),
+                            + "applying theme for its imports", file.getPath(),
                             exception);
         }
     }

flow-server/src/test/java/com/vaadin/flow/server/frontend/NodeUpdateImportsTest.java

@@ -32,6 +32,7 @@
 import java.util.Set;
 import java.util.stream.Collectors;
 
+import com.vaadin.flow.server.Constants;
 import org.apache.commons.io.FileUtils;
 import org.hamcrest.CoreMatchers;
 import org.junit.After;
@@ -43,6 +44,7 @@
 import org.junit.rules.TemporaryFolder;
 import org.mockito.ArgumentCaptor;
 import org.mockito.Mockito;
+import org.mockito.internal.util.collections.Sets;
 import org.slf4j.Logger;
 import org.slf4j.impl.SimpleLogger;
 
@@ -52,8 +54,9 @@
 import static com.vaadin.flow.server.frontend.FrontendUtils.IMPORTS_NAME;
 import static com.vaadin.flow.server.frontend.FrontendUtils.NODE_MODULES;
 import static com.vaadin.flow.server.frontend.FrontendUtils.WEBPACK_PREFIX_ALIAS;
-import static org.junit.Assert.assertFalse;
+import static org.hamcrest.MatcherAssert.assertThat;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.assertFalse;
 
 public class NodeUpdateImportsTest extends NodeUpdateTestUtil {
 
@@ -105,9 +108,9 @@ Logger log() {
             }
         };
 
-        Assert.assertTrue(nodeModulesPath.mkdirs());
+        assertTrue(nodeModulesPath.mkdirs());
         createExpectedImports(frontendDirectory, nodeModulesPath);
-        Assert.assertTrue(new File(nodeModulesPath,
+        assertTrue(new File(nodeModulesPath,
                 FLOW_NPM_PACKAGE_NAME + "ExampleConnector.js").exists());
     }
 
@@ -139,12 +142,12 @@ public void getModuleLines_npmPackagesDontExist_logExplanation() {
         boolean atLeastOneRemoved = false;
         for (String imprt : getExpectedImports()) {
             if (imprt.startsWith("@vaadin") && imprt.endsWith(".js")) {
-                Assert.assertTrue(resolveImportFile(nodeModulesPath,
+                assertTrue(resolveImportFile(nodeModulesPath,
                         nodeModulesPath, imprt).delete());
                 atLeastOneRemoved = true;
             }
         }
-        Assert.assertTrue(atLeastOneRemoved);
+        assertTrue(atLeastOneRemoved);
         updater.execute();
 
         ArgumentCaptor<String> captor = ArgumentCaptor.forClass(String.class);
@@ -161,6 +164,67 @@ public void getModuleLines_npmPackagesDontExist_logExplanation() {
                         "In addition you may run `npm install` to fix `node_modules` tree structure.")));
     }
 
+    @Test
+    public void getModuleLines_oneFrontendDependencyDoesntExist_throwExceptionAndlogExplanation() {
+        useMockLog = true;
+        Mockito.when(logger.isInfoEnabled()).thenReturn(true);
+
+        String fooFileName = "./foo.js";
+        assertFileRemoved(fooFileName, frontendDirectory);
+
+        try {
+            updater.execute();
+            Assert.fail("Execute should have failed with missing file");
+        } catch (IllegalStateException e) {
+            assertThat(e.getCause().getMessage(),
+                    CoreMatchers.containsString(getFormattedFrontendErrorMessage(Sets.newSet(fooFileName))));
+        }
+
+    }
+
+    @Test
+    public void getModuleLines_multipleFrontendDependencyDoesntExist_throwExceptionAndlogExplanation() {
+        useMockLog = true;
+        Mockito.when(logger.isInfoEnabled()).thenReturn(true);
+
+        String localTemplateFileName = "./local-template.js";
+        String fooFileName = "./foo.js";
+
+        assertFileRemoved(localTemplateFileName, frontendDirectory);
+        assertFileRemoved(fooFileName, frontendDirectory);
+
+        try {
+            updater.execute();
+            Assert.fail("Execute should have failed with missing files");
+        } catch (IllegalStateException e) {
+            assertThat(e.getCause().getMessage(),
+                    CoreMatchers.containsString(getFormattedFrontendErrorMessage(Sets.newSet(localTemplateFileName, fooFileName))));
+        }
+
+    }
+
+    private void assertFileRemoved(String fileName, File directory) {
+        assertTrue(String.format("File `%s` was not removed from, or does not exist in, `%s`",
+                fileName, directory),
+                resolveImportFile(directory, directory, fileName).delete());
+    }
+
+    private String getFormattedFrontendErrorMessage(Set<String> resourcesNotFound) {
+        String prefix =  "Failed to find the following files: ";
+
+        String suffix = String.format(
+                "%n  Locations searched were:"
+                        + "%n      - `%s` in this project"
+                        + "%n      - `%s` in included JARs"
+                        + "%n%n  Please, double check that those files exist. If you use a custom directory "
+                        + "for your resource files instead of default "
+                        + "`frontend` folder then make sure you it's correctly configured "
+                        + "(e.g. set '%s' property)", frontendDirectory.getPath(), Constants.RESOURCES_FRONTEND_DEFAULT, FrontendUtils.PARAM_FRONTEND_DIR);
+
+        return String.format("%n%n  %s%n      - %s%n  %s%n%n", prefix,
+                String.join("\n      - ", resourcesNotFound), suffix);
+    }
+
     @Test
     public void should_UpdateMainJsFile() throws Exception {
         List<String> expectedLines = new ArrayList<>(Arrays.asList(
@@ -228,7 +292,7 @@ public void should_UpdateMainJsFile() throws Exception {
 
     @Test
     public void should_ThrowException_WhenCssFileNotFound() {
-        Assert.assertTrue(resolveImportFile(frontendDirectory, nodeModulesPath,
+        assertTrue(resolveImportFile(frontendDirectory, nodeModulesPath,
                 "@vaadin/vaadin-mixed-component/bar.css").delete());
         exception.expect(IllegalStateException.class);
         updater.execute();