Added initial npm diff.

npm/npm-diff/action.yaml

@@ -0,0 +1,63 @@
+name: npm-diff
+description: "Compare two versions of an NPM package using npm diff."
+inputs:
+  name:
+    description: "Name of the package to diff."
+    required: true
+  lhsVersion:
+    description: "Left-hand side version (older version) to compare. If not specified, uses the latest version."
+    required: false
+    default: ""
+  rhsVersion:
+    description: "Right-hand side version (newer version) to compare. If not specified, compares against the working directory."
+    required: false
+    default: ""
+  workingDirectory:
+    description: "Working directory containing package.json (for comparing local changes)."
+    required: false
+    default: "."
+  nodeVersion:
+    description: "Node.js version to use."
+    required: false
+    default: "20"
+  registry:
+    description: "NPM registry URL."
+    required: false
+    default: "https://npm.pkg.github.com"
+  authToken:
+    description: "Authentication token for the registry."
+    required: true
+    default: "{{ github.token }}"
+  diffOptions:
+    description: "Additional options to pass to npm diff (e.g., '--diff-ignore-whitespace')."
+    required: false
+    default: ""
+  outputFile:
+    description: "File path to save diff output (optional). If not specified, outputs to console only."
+    required: false
+    default: ""
+  failOnDifferences:
+    description: "Whether to fail the action if differences are found."
+    required: false
+    default: "true"
+outputs:
+  hasDifferences:
+    description: "Whether differences were found between the versions."
+    value: ${{ steps.diff.outputs.hasDifferences }}
+  diffOutput:
+    description: "The diff output (truncated if too large)."
+    value: ${{ steps.diff.outputs.diffOutput }}
+runs:
+  using: "composite"
+  steps:
+  - name: "Setup Node.js"
+    uses: https://github.com/actions/setup-node@v4
+    with:
+      node-version: ${{ inputs.nodeVersion }}
+      registry-url: ${{ inputs.registry }}
+  - name: "Run npm diff"
+    id: diff
+    env:
+      NODE_AUTH_TOKEN: ${{ inputs.authToken }}
+    run: bash ${{ github.action_path }}/npm_diff.sh "${{ inputs.name }}" "${{ inputs.lhsVersion }}" "${{ inputs.rhsVersion }}" "${{ inputs.workingDirectory }}" "${{ inputs.registry }}" "${{ inputs.diffOptions }}" "${{ inputs.outputFile }}" "${{ inputs.failOnDifferences }}"
+    shell: bash

npm/npm-diff/npm_diff.sh

@@ -0,0 +1,110 @@
+#!/bin/bash
+set -e
+
+PACKAGE_NAME="$1"
+LHS_VERSION="$2"
+RHS_VERSION="$3"
+WORKING_DIR="$4"
+REGISTRY="$5"
+DIFF_OPTIONS="$6"
+OUTPUT_FILE="$7"
+FAIL_ON_DIFF="$8"
+
+if [[ ! -f "$GITHUB_OUTPUT" ]]; then
+    GITHUB_OUTPUT="/dev/fd/1"
+fi
+
+# Change to working directory if specified
+if [[ -n "$WORKING_DIR" && "$WORKING_DIR" != "." ]]; then
+    cd "$WORKING_DIR"
+fi
+
+# Configure npm registry
+if [[ -n "$REGISTRY" && "$REGISTRY" != "https://registry.npmjs.org" ]]; then
+    npm config set registry "$REGISTRY"
+fi
+
+# Build the npm diff command
+DIFF_CMD="npm diff"
+
+# Add package specs using correct --diff syntax
+if [[ -n "$PACKAGE_NAME" ]]; then
+    if [[ -n "$LHS_VERSION" && -n "$RHS_VERSION" ]]; then
+        # Compare two specific published versions (LHS as "from", RHS as "to")
+        DIFF_CMD="$DIFF_CMD --diff=$PACKAGE_NAME@$LHS_VERSION --diff=$PACKAGE_NAME@$RHS_VERSION"
+    elif [[ -n "$LHS_VERSION" ]]; then
+        # Compare local/installed to the specified LHS version
+        DIFF_CMD="$DIFF_CMD --diff=$PACKAGE_NAME@$LHS_VERSION"
+    elif [[ -n "$RHS_VERSION" ]]; then
+        # Compare local/installed to the specified RHS version
+        DIFF_CMD="$DIFF_CMD --diff=$PACKAGE_NAME@$RHS_VERSION"
+    else
+        # Compare local/installed to the latest published version
+        DIFF_CMD="$DIFF_CMD --diff=$PACKAGE_NAME"
+    fi
+else
+    # No package name provided: compare current workspace to its latest published version
+    # (standard behavior of plain `npm diff` in a package directory)
+    :
+fi
+
+# Add any additional diff options (e.g., --diff-name-only, file paths for filtering, etc.)
+if [[ -n "$DIFF_OPTIONS" ]]; then
+    DIFF_CMD="$DIFF_CMD $DIFF_OPTIONS"
+fi
+
+echo "Running: $DIFF_CMD"
+
+# Run npm diff and capture output
+DIFF_OUTPUT=$(eval "$DIFF_CMD" 2>&1) || DIFF_EXIT_CODE=$?
+
+# npm diff returns exit code 0 if no differences, 1 if differences found
+if [[ -z "$DIFF_EXIT_CODE" ]]; then
+    DIFF_EXIT_CODE=0
+fi
+
+# Determine if differences were found
+if [[ $DIFF_EXIT_CODE -eq 0 ]]; then
+    HAS_DIFFERENCES="false"
+    echo "No differences found"
+else
+    HAS_DIFFERENCES="true"
+    echo "Differences found"
+fi
+
+# Save diff output to file if specified
+if [[ -n "$OUTPUT_FILE" ]]; then
+    echo "$DIFF_OUTPUT" > "$OUTPUT_FILE"
+    echo "Diff output saved to $OUTPUT_FILE"
+fi
+
+# Output the diff to console
+if [[ -n "$DIFF_OUTPUT" ]]; then
+    echo "========== DIFF OUTPUT =========="
+    echo "$DIFF_OUTPUT"
+    echo "================================="
+fi
+
+# Set output variables (truncate diffOutput if too large)
+echo "hasDifferences=$HAS_DIFFERENCES" >> "$GITHUB_OUTPUT"
+
+# Truncate diff output for GitHub Actions output (max ~1MB)
+TRUNCATED_OUTPUT=$(echo "$DIFF_OUTPUT" | head -c 100000)
+if [[ ${#DIFF_OUTPUT} -gt 100000 ]]; then
+    TRUNCATED_OUTPUT="$TRUNCATED_OUTPUT... (output truncated)"
+fi
+
+# Use multiline output format for GitHub Actions
+{
+    echo "diffOutput<<EOF"
+    echo "$TRUNCATED_OUTPUT"
+    echo "EOF"
+} >> "$GITHUB_OUTPUT"
+
+# Fail if differences found and failOnDifferences is true
+if [[ "$HAS_DIFFERENCES" == "true" && "$FAIL_ON_DIFF" == "true" ]]; then
+    echo "Error: Differences found and failOnDifferences is set to true"
+    exit 1
+fi
+
+exit 0