feat: isTransitive(pkg)

Author: FauxFaux

src/core/dep-graph.ts

@@ -158,6 +158,14 @@ class DepGraphImpl implements types.DepGraphInternal {
     return count;
   }
 
+  public isTransitive(pkg: types.Pkg): boolean {
+    const checking = new Set(this.getPkgNodeIds(pkg));
+    for (const directDep of this.getNodeDepsNodeIds(this.rootNodeId)) {
+      if (checking.has(directDep)) return false;
+    }
+    return true;
+  }
+
   public equals(
     other: types.DepGraph,
     { compareRoot = true }: { compareRoot?: boolean } = {},

src/core/types.ts

@@ -94,6 +94,7 @@ export interface DepGraph {
   getPkgNodes(pkg: Pkg): Node[];
   toJSON(): DepGraphData;
   pkgPathsToRoot(pkg: Pkg, opts?: { limit?: number }): PkgInfo[][];
+  isTransitive(pkg: Pkg): boolean;
   directDepsLeadingTo(pkg: Pkg): PkgInfo[];
   countPathsToRoot(pkg: Pkg): number;
   equals(other: DepGraph, options?: { compareRoot?: boolean }): boolean;

test/core/is-transitive.test.ts

@@ -0,0 +1,41 @@
+import { createFromJSON, DepGraphData } from '../../src';
+import { loadFixture } from '../helpers';
+import * as depGraphLib from '../../src';
+
+describe('isTransitive', () => {
+  it('checks direct', () => {
+    const graphJson: DepGraphData = loadFixture('simple-graph.json');
+
+    const depGraph = createFromJSON(graphJson);
+
+    expect(depGraph.isTransitive({ name: 'a', version: '1.0.0' })).toBe(false);
+    expect(depGraph.isTransitive({ name: 'b', version: '1.0.0' })).toBe(false);
+    expect(depGraph.isTransitive({ name: 'e', version: '5.0.0' })).toBe(true);
+    expect(depGraph.isTransitive({ name: 'd', version: '0.0.1' })).toBe(true);
+    expect(depGraph.isTransitive({ name: 'd', version: '0.0.2' })).toBe(true);
+    expect(depGraph.isTransitive({ name: 'c', version: '1.0.0' })).toBe(true);
+  });
+
+  it('assume non-transitive if any directly depends', () => {
+    const builder = new depGraphLib.DepGraphBuilder(
+      { name: 'npm' },
+      { name: 'root', version: '1.2.3' },
+    );
+    const rootNodeId = 'root-node';
+
+    // root depends on 'a' and 'b', 'b' depends again on 'a'.
+    builder.addPkgNode({ name: 'a', version: '1.0.0' }, 'a|1');
+    builder.connectDep(rootNodeId, 'a|1');
+
+    builder.addPkgNode({ name: 'b', version: '1.0.0' }, 'b');
+    builder.connectDep(rootNodeId, 'b');
+
+    builder.addPkgNode({ name: 'a', version: '1.0.0' }, 'a|2');
+    builder.connectDep('b', 'a|2');
+
+    const depGraph = builder.build();
+
+    expect(depGraph.isTransitive({ name: 'a', version: '1.0.0' })).toBe(false);
+    expect(depGraph.isTransitive({ name: 'b', version: '1.0.0' })).toBe(false);
+  });
+});