test: implement dependency graph building tests

Author: galargh

v-next/hardhat/test/fixture-projects/solidity/example-project/contracts/A.sol

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+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.0;
+pragma solidity *;
+
+import "./B.sol";
+
+contract A is B {}

v-next/hardhat/test/fixture-projects/solidity/example-project/contracts/B.sol

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+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.0;
+
+import "@openzeppelin/contracts/access/Ownable.sol";
+
+contract B {}

v-next/hardhat/test/fixture-projects/solidity/example-project/contracts/C.sol

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+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.0;
+
+import "./B.sol";
+
+contract C {}
+
+contract C2 {}

v-next/hardhat/test/fixture-projects/solidity/example-project/contracts/D.sol

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+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.22;
+
+import "./C.sol";

v-next/hardhat/test/fixture-projects/solidity/example-project/contracts/E.sol

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+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.22;
+
+import "./C.sol";

v-next/hardhat/test/fixture-projects/solidity/example-project/contracts/NoImports.sol

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+// SPDX-License-Identifier: SEE LICENSE IN LICENSE
+pragma solidity ^0.7.0;
+
+contract NoImports {}

v-next/hardhat/test/fixture-projects/solidity/example-project/contracts/UserRemappedImport.sol

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+// SPDX-License-Identifier: SEE LICENSE IN LICENSE
+pragma solidity ^0.8.0;
+
+import "remapped/Ownable.sol";

v-next/hardhat/test/fixture-projects/solidity/example-project/node_modules/@openzeppelin/contracts/access/Ownable.sol

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+import assert from "node:assert/strict";
+import path from "node:path";
+import { describe, it } from "node:test";
+
+import { useFixtureProject } from "@nomicfoundation/hardhat-test-utils";
+
+import { buildDependencyGraph } from "../../../../../src/internal/builtin-plugins/solidity/build-system/dependency-graph-building.js";
+
+describe("buildDependencyGraph", () => {
+  useFixtureProject("solidity/example-project");
+
+  it("should return an empty graph if no files are provided", async () => {
+    const { dependencyGraph, resolver } = await buildDependencyGraph(
+      [],
+      process.cwd(),
+      [],
+    );
+
+    assert.equal(dependencyGraph.getRoots().size, 0);
+    assert.equal(Array.from(dependencyGraph.getAllFiles()).length, 0);
+
+    assert.equal(resolver.getRemappings().length, 0);
+  });
+
+  it("should build a graph from given files", async () => {
+    const rootSourceNames = [
+      "contracts/A.sol",
+      "contracts/D.sol",
+      "contracts/NoImports.sol",
+      "contracts/UserRemappedImport.sol",
+    ];
+    const dependencySourceNames = [
+      "contracts/B.sol",
+      "contracts/C.sol",
+      "npm/@openzeppelin/[email protected]/access/Ownable.sol",
+    ];
+
+    const { dependencyGraph, resolver } = await buildDependencyGraph(
+      rootSourceNames.map((sourceName) => path.join(process.cwd(), sourceName)),
+      process.cwd(),
+      ["remapped/=npm/@openzeppelin/[email protected]/access/"],
+    );
+
+    const roots = dependencyGraph.getRoots();
+    assert.equal(
+      roots.size,
+      rootSourceNames.length,
+      `Should have ${rootSourceNames.length} roots`,
+    );
+    for (const sourceName of rootSourceNames) {
+      assert.ok(roots.has(sourceName), `Should have root ${sourceName}`);
+    }
+
+    const files = Array.from(dependencyGraph.getAllFiles()).map(
+      (file) => file.sourceName,
+    );
+    assert.equal(files.length, 7, "Should have 7 files");
+    for (const sourceName of rootSourceNames.concat(dependencySourceNames)) {
+      assert.ok(files.includes(sourceName), `Should have file ${sourceName}`);
+    }
+
+    const remappings = resolver.getRemappings();
+    assert.equal(remappings.length, 2, "Should have 2 remappings");
+    assert.ok(
+      remappings.some(
+        (r) =>
+          r.context === "" &&
+          r.prefix === "remapped/" &&
+          r.target === "npm/@openzeppelin/[email protected]/access/",
+      ),
+      "Should have remapping for Ownable.sol",
+    );
+    assert.ok(
+      remappings.some(
+        (r) =>
+          r.context === "" &&
+          r.prefix === "@openzeppelin/contracts/" &&
+          r.target === "npm/@openzeppelin/[email protected]/",
+      ),
+      "Should have remapping for @openzeppelin/contracts",
+    );
+  });
+});