TEP-0090 Matrix: Refactor Matrix FanOut() to use the Matrix Struct

[TEP-0090: Matrix] introduced `Matrix` to the `PipelineTask` specification such that the `PipelineTask` executes a list of `TaskRuns` or `Runs` in parallel with the specified list of inputs for a `Parameter` or with different combinations of the inputs for a set of `Parameters`.

This PR refactors the FanOut() function to use the Matrix struct instead of the old []Params.

pkg/matrix/matrix.go

@@ -18,9 +18,9 @@ import (
 )
 
 // FanOut produces combinations of Parameters of type String from a slice of Parameters of type Array.
-func FanOut(params []v1beta1.Param) Combinations {
+func FanOut(matrix v1beta1.Matrix) Combinations {
 	var combinations Combinations
-	for _, parameter := range params {
+	for _, parameter := range matrix.Params {
 		combinations = combinations.fanOut(parameter)
 	}
 	return combinations

pkg/matrix/matrix_test.go

@@ -23,14 +23,22 @@ import (
 func Test_FanOut(t *testing.T) {
 	tests := []struct {
 		name             string
-		matrix           []v1beta1.Param
+		matrix           *v1beta1.Matrix
 		wantCombinations Combinations
 	}{{
+		name: "matrix with no params",
+		matrix: &v1beta1.Matrix{
+			Params: []v1beta1.Param{},
+		},
+		wantCombinations: nil,
+	}, {
 		name: "single array in matrix",
-		matrix: []v1beta1.Param{{
-			Name:  "platform",
-			Value: v1beta1.ParamValue{Type: v1beta1.ParamTypeArray, ArrayVal: []string{"linux", "mac", "windows"}},
-		}},
+		matrix: &v1beta1.Matrix{
+			Params: []v1beta1.Param{{
+				Name:  "platform",
+				Value: v1beta1.ParamValue{Type: v1beta1.ParamTypeArray, ArrayVal: []string{"linux", "mac", "windows"}},
+			}},
+		},
 		wantCombinations: Combinations{{
 			MatrixID: "0",
 			Params: []v1beta1.Param{{
@@ -52,13 +60,14 @@ func Test_FanOut(t *testing.T) {
 		}},
 	}, {
 		name: "multiple arrays in matrix",
-		matrix: []v1beta1.Param{{
-			Name:  "platform",
-			Value: v1beta1.ParamValue{Type: v1beta1.ParamTypeArray, ArrayVal: []string{"linux", "mac", "windows"}},
-		}, {
-			Name:  "browser",
-			Value: v1beta1.ParamValue{Type: v1beta1.ParamTypeArray, ArrayVal: []string{"chrome", "safari", "firefox"}},
-		}},
+		matrix: &v1beta1.Matrix{
+			Params: []v1beta1.Param{{
+				Name:  "platform",
+				Value: v1beta1.ParamValue{Type: v1beta1.ParamTypeArray, ArrayVal: []string{"linux", "mac", "windows"}},
+			}, {
+				Name:  "browser",
+				Value: v1beta1.ParamValue{Type: v1beta1.ParamTypeArray, ArrayVal: []string{"chrome", "safari", "firefox"}},
+			}}},
 		wantCombinations: Combinations{{
 			MatrixID: "0",
 			Params: []v1beta1.Param{{
@@ -144,7 +153,7 @@ func Test_FanOut(t *testing.T) {
 	}}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			gotCombinations := FanOut(tt.matrix)
+			gotCombinations := FanOut(*tt.matrix)
 			if d := cmp.Diff(tt.wantCombinations, gotCombinations); d != "" {
 				t.Errorf("Combinations of Parameters did not match the expected Combinations: %s", d)
 			}

pkg/reconciler/pipelinerun/pipelinerun.go

@@ -834,7 +834,7 @@ func (c *Reconciler) createTaskRuns(ctx context.Context, rpt *resources.Resolved
 	ctx, span := c.tracerProvider.Tracer(TracerName).Start(ctx, "createTaskRuns")
 	defer span.End()
 	var taskRuns []*v1beta1.TaskRun
-	matrixCombinations := matrix.FanOut(rpt.PipelineTask.Matrix.Params).ToMap()
+	matrixCombinations := matrix.FanOut(*rpt.PipelineTask.Matrix).ToMap()
 	for i, taskRunName := range rpt.TaskRunNames {
 		params := matrixCombinations[strconv.Itoa(i)]
 		taskRun, err := c.createTaskRun(ctx, taskRunName, params, rpt, pr, storageBasePath)
@@ -909,7 +909,7 @@ func (c *Reconciler) createRunObjects(ctx context.Context, rpt *resources.Resolv
 	var runObjects []v1beta1.RunObject
 	ctx, span := c.tracerProvider.Tracer(TracerName).Start(ctx, "createRunObjects")
 	defer span.End()
-	matrixCombinations := matrix.FanOut(rpt.PipelineTask.Matrix.Params).ToMap()
+	matrixCombinations := matrix.FanOut(*rpt.PipelineTask.Matrix).ToMap()
 	for i, runObjectName := range rpt.RunObjectNames {
 		params := matrixCombinations[strconv.Itoa(i)]
 		runObject, err := c.createRunObject(ctx, runObjectName, params, rpt, pr)