fix: fqn resolution of artifacts

packages/hardhat-plugin/src/hardhat-artifact-resolver.ts

@@ -14,6 +14,17 @@ export class HardhatArtifactResolver implements ArtifactResolver {
   public async getBuildInfo(
     contractName: string
   ): Promise<BuildInfo | undefined> {
+    // If a fully qualified name is used, we can can
+    // leverage the artifact manager directly to load the build
+    // info.
+    if (this._isFullyQualifiedName(contractName)) {
+      return this._hre.artifacts.getBuildInfo(contractName);
+    }
+
+    // Otherwise we have only the contract name, and need to
+    // resolve the artifact for the contract ourselves.
+    // We can build on the assumption that the contract name
+    // is unique based on Module validation.
     const artifactPath = await this._resolvePath(contractName);
 
     if (artifactPath === undefined) {
@@ -51,4 +62,14 @@ export class HardhatArtifactResolver implements ArtifactResolver {
   public loadArtifact(contractName: string): Promise<Artifact> {
     return this._hre.artifacts.readArtifact(contractName);
   }
+
+  /**
+   * Returns true if a name is fully qualified, and not just a bare contract name.
+   *
+   * This is based on Hardhat's own test for fully qualified names, taken
+   * from `contract-names.ts` in `hardhat-core` utils.
+   */
+  private _isFullyQualifiedName(contractName: string): boolean {
+    return contractName.includes(":");
+  }
 }

packages/hardhat-plugin/test/fixture-projects/multiple-contracts-with-same-name/contracts/Rocket1.sol

@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.0;
+
+// This contract name is the same as in `./Rocket2.sol`
+contract Rocket {
+    string public name;
+
+    constructor(string memory _name) {
+        name = _name;
+    }
+}

packages/hardhat-plugin/test/fixture-projects/multiple-contracts-with-same-name/contracts/Rocket2.sol

@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.0;
+
+// This contract name is the same as in `./Rocket1.sol`
+contract Rocket {
+    string public name;
+
+    constructor(string memory _name) {
+        name = _name;
+    }
+}

packages/hardhat-plugin/test/fixture-projects/multiple-contracts-with-same-name/hardhat.config.js

@@ -0,0 +1,5 @@
+require("../../../src/index");
+
+module.exports = {
+  solidity: "0.8.19",
+};

packages/hardhat-plugin/test/module-api/fully-qualified-names.ts

@@ -0,0 +1,39 @@
+import { buildModule } from "@nomicfoundation/ignition-core";
+import { assert } from "chai";
+
+import { useFileIgnitionProject } from "../test-helpers/use-ignition-project";
+
+describe("fully qualified names", () => {
+  describe("where there are multiple contracts with the same name in the project", () => {
+    useFileIgnitionProject(
+      "multiple-contracts-with-same-name",
+      "contract-deploy"
+    );
+
+    it("should deploy contracts by referring using fully qualified names", async function () {
+      const LaunchModule = buildModule("Apollo", (m) => {
+        const rocket1 = m.contract(
+          "contracts/Rocket1.sol:Rocket",
+          ["Rocket 1"],
+          {
+            id: "Rocket1",
+          }
+        );
+        const rocket2 = m.contract(
+          "contracts/Rocket2.sol:Rocket",
+          ["Rocket 2"],
+          {
+            id: "Rocket2",
+          }
+        );
+
+        return { rocket1, rocket2 };
+      });
+
+      const result = await this.hre.ignition.deploy(LaunchModule);
+
+      assert.equal(await result.rocket1.read.name(), "Rocket 1");
+      assert.equal(await result.rocket2.read.name(), "Rocket 2");
+    });
+  });
+});