Create tagged template for error messages

extensions/ql-vscode/src/common/errors.ts

@@ -0,0 +1,37 @@
+export class RedactableErrorMessage {
+  constructor(
+    private readonly strings: TemplateStringsArray,
+    private readonly values: unknown[],
+  ) {}
+
+  public toString(): string {
+    return this.fullMessage;
+  }
+
+  public get fullMessage(): string {
+    return this.strings
+      .map((s, i) => s + (this.hasValue(i) ? this.getValue(i) : ""))
+      .join("");
+  }
+
+  public get redactedMessage(): string {
+    return this.strings
+      .map((s, i) => s + (this.hasValue(i) ? "[REDACTED]" : ""))
+      .join("");
+  }
+
+  private getValue(index: number): unknown {
+    return this.values[index];
+  }
+
+  private hasValue(index: number): boolean {
+    return index < this.values.length;
+  }
+}
+
+export function errorMessage(
+  strings: TemplateStringsArray,
+  ...values: unknown[]
+): RedactableErrorMessage {
+  return new RedactableErrorMessage(strings, values);
+}

extensions/ql-vscode/test/unit-tests/common/errors.test.ts

@@ -0,0 +1,30 @@
+import {
+  errorMessage,
+  RedactableErrorMessage,
+} from "../../../src/common/errors";
+
+describe("errorMessage", () => {
+  it("creates a RedactableErrorMessage", () => {
+    expect(errorMessage`Failed to create database ${"foo"}`).toBeInstanceOf(
+      RedactableErrorMessage,
+    );
+  });
+
+  it("toString() matches the given message", () => {
+    expect(errorMessage`Failed to create database ${"foo"}`.toString()).toEqual(
+      "Failed to create database foo",
+    );
+  });
+
+  it("fullMessage matches the given message", () => {
+    expect(
+      errorMessage`Failed to create database ${"foo"}`.fullMessage,
+    ).toEqual("Failed to create database foo");
+  });
+
+  it("redactedMessage redacts the given message", () => {
+    expect(
+      errorMessage`Failed to create database ${"foo"}`.redactedMessage,
+    ).toEqual("Failed to create database [REDACTED]");
+  });
+});