fix(compiler): correct module-resolver error messages @bug W-5192589@

packages/lwc-compiler/src/__tests__/index.spec.ts

@@ -59,6 +59,6 @@ describe("test index entry points", () => {
         const { success, diagnostics }  = await compile(config);
         expect(success).toBe(false);
         expect(diagnostics.length).toBe(1);
-        expect(diagnostics[0].message).toBe("Could not resolve 'foo' (as foo.js) from compiler entry point");
+        expect(diagnostics[0].message).toBe("Failed to resolve entry for module foo");
     });
 });

packages/lwc-compiler/src/compiler/__tests__/result.spec.ts

@@ -150,7 +150,7 @@ describe("compiler result", () => {
         const { level, message } = diagnostics[0];
 
         expect(level).toBe(DiagnosticLevel.Fatal);
-        expect(message).toContain('Could not resolve \'./nothing\' (as nothing.js) from \'foo.js\'');
+        expect(message).toContain('./nothing failed to be resolved from foo.js');
     });
 
     test('compiler returns diagnostic errors when transformation encounters an error in javascript', async () => {

packages/lwc-compiler/src/rollup-plugins/__tests__/module-resolver.spec.ts

@@ -1,4 +1,5 @@
 import { compile } from "../../compiler/compiler";
+import { DiagnosticLevel } from "../../diagnostics/diagnostic";
 import { pretify, readFixture } from "../../__tests__/utils";
 
 const VALID_CONFIG = {
@@ -111,4 +112,48 @@ describe("module resolver", () => {
                 });`)
         );
     });
+
+    test("compiler should resolve bundle with local import", async () => {
+        const COMPILER_CONFIG_BASEDIR = {
+            name: "foo",
+            namespace: "x",
+            files: {
+                "foo.js": `import { nested } from './lib/foo';`,
+                "lib/foo.js": `export function nested(){ return null;}`
+            }
+        };
+
+        const { result, success } = await compile(COMPILER_CONFIG_BASEDIR);
+        expect(success).toBe(true);
+        expect(result).toBeDefined();
+    });
+
+    test("compiler should report fatal diagnostic if local import cannot be resolved", async () => {
+        const COMPILER_CONFIG_BASEDIR = {
+            name: "foo",
+            namespace: "x",
+            files: {
+                "foo.js": `import { nested } from './lib/foo';`,
+            }
+        };
+
+        const { diagnostics, success } = await compile(COMPILER_CONFIG_BASEDIR);
+        expect(success).toBe(false);
+        expect(diagnostics[0].level).toBe(DiagnosticLevel.Fatal);
+    });
+
+    test("compiler should report fatal diagnostic when invalid entry path is specified", async () => {
+        const COMPILER_CONFIG_BASEDIR = {
+            name: "modules/foo",
+            namespace: "x",
+            files: {
+                "foo.js": ``,
+            }
+        };
+
+        const { diagnostics, success } = await compile(COMPILER_CONFIG_BASEDIR);
+        expect(success).toBe(false);
+        expect(diagnostics[0].level).toBe(DiagnosticLevel.Fatal);
+    });
+
 });

packages/lwc-compiler/src/rollup-plugins/module-resolver.ts

@@ -66,12 +66,12 @@ export default function({
             ) {
                 if (importer) {
                     throw new CompilerError(
-                        `Could not resolve '${importee}' (as ${absPath}) from '${importer}'`,
+                        `${importee} failed to be resolved from ${importer}`,
                         importer,
                     );
                 }
                 throw new CompilerError(
-                    `Could not resolve '${importee}' (as ${absPath}) from compiler entry point`,
+                    `Failed to resolve entry for module ${importee}`,
                     importer,
                 );
             }