Improve script/category name validation

- Use better error messages with more context.
- Unify their validation logic and share tests.
- Validate also type of the name.
- Refactor node (Script/Category) parser tests for easier future
  changes and cleaner test code (using `TestBuilder` to do dirty work in
  unified way).
- Add more tests. Custom `Error` properties are compared manually due to
  `chai` not supporting deep equality checks (chaijs/chai#1065,
  chaijs/chai#1405).

src/application/Parser/NodeValidation/NodeValidator.ts

@@ -0,0 +1,38 @@
+import { INodeDataErrorContext, NodeDataError } from './NodeDataError';
+import { NodeData } from './NodeData';
+
+export class NodeValidator {
+  constructor(private readonly context: INodeDataErrorContext) {
+
+  }
+
+  public assertValidName(nameValue: string) {
+    return this
+      .assert(
+        () => Boolean(nameValue),
+        'missing name',
+      )
+      .assert(
+        () => typeof nameValue === 'string',
+        `Name (${JSON.stringify(nameValue)}) is not a string but ${typeof nameValue}.`,
+      );
+  }
+
+  public assertDefined(node: NodeData) {
+    return this.assert(
+      () => node !== undefined && node !== null && Object.keys(node).length > 0,
+      'missing node data',
+    );
+  }
+
+  public assert(validationPredicate: () => boolean, errorMessage: string) {
+    if (!validationPredicate()) {
+      this.throw(errorMessage);
+    }
+    return this;
+  }
+
+  public throw(errorMessage: string) {
+    throw new NodeDataError(errorMessage, this.context);
+  }
+}