Resolve CodeReview comments for:

1. libraries/rush-lib/src/logic/operations/WeightedOperationPlugin.ts
   - Added more comments to explain the percentage weight convert function.
   - Use `as` syntax to cast error to Error type for better readability.

2. libraries/rush-lib/src/schemas/rush-project.schema.json
    - Updated the description of the weight property to reflect that the maximum concurrency units is determined by `os.availableParallelism()`.

3. libraries/rush-lib/src/logic/operations/test/WeightedOperationPlugin.test.ts
    - Fix a test name.

Author: LPegasus

libraries/rush-lib/src/logic/operations/WeightedOperationPlugin.ts

@@ -37,6 +37,15 @@ function weightOperations(
 
   const percentageRegExp: RegExp = /^[1-9][0-9]*(\.\d+)?%$/;
 
+  /**
+   * Since the JSON value is a string, it must be a percentage like "50%",
+   * which we convert to a number based on the available parallelism.
+   * For example, if the available parallelism (not the -p flag) is 8 and the weight is "50%",
+   * then the resulting weight will be 4.
+   *
+   * @param weight
+   * @returns
+   */
   function _tryConvertPercentWeight(weight: `${number}%`): number {
     if (!percentageRegExp.test(weight)) {
       throw new Error(`Expected a percentage string like "100%".`);
@@ -65,7 +74,7 @@ function weightOperations(
             operation.weight = _tryConvertPercentWeight(operationSettings.weight);
           } catch (error) {
             throw new Error(
-              `${operation.name} (invalid weight: ${operationSettings.weight}) ${error instanceof Error ? error.message : String(error)}`
+              `${operation.name} (invalid weight: ${JSON.stringify(operationSettings.weight)}) ${(error as Error).message}`
             );
           }
         }

libraries/rush-lib/src/logic/operations/test/WeightedOperationPlugin.test.ts

@@ -149,10 +149,10 @@ describe(WeightedOperationPlugin.name, () => {
     expect(operation.weight).toBe(4);
   });
 
-  it('use ceiling when converting percentage weight to avoid zero weight', async () => {
+  it('use floor when converting percentage weight to avoid zero weight', async () => {
     mockAvailableParallelism(16);
 
-    const project: RushConfigurationProject = createProject('project-ceiling');
+    const project: RushConfigurationProject = createProject('project-floor');
     const operation: Operation = createOperation({
       project,
       settings: {
@@ -197,6 +197,6 @@ describe(WeightedOperationPlugin.name, () => {
 
     await expect(
       applyWeightPluginAsync(createExecutionRecords(operation), createContext(new Map()))
-    ).rejects.toThrow(/invalid weight: 12.5a%/i);
+    ).rejects.toThrow(/invalid weight: "12.5a%"/i);
   });
 });

libraries/rush-lib/src/schemas/rush-project.schema.json

@@ -110,7 +110,7 @@
               {
                 "type": "string",
                 "pattern": "^[1-9][0-9]*(\\.\\d+)?%$",
-                "description": "The percentage of concurrency units that this operation should take up. The maximum concurrency units is determined by the -p flag."
+                "description": "The percentage of concurrency units that this operation should take up. The maximum concurrency units is determined by `os.availableParallelism()`."
               },
               {
                 "description": "The number of concurrency units that this operation should take up. The maximum concurrency units is determined by the -p flag.",