feat: resolve array values in Input of When expressions

pkg/apis/pipeline/v1/when_types.go

@@ -17,6 +17,7 @@ limitations under the License.
 package v1
 
 import (
+	"encoding/json"
 	"fmt"
 
 	"github.com/tektoncd/pipeline/pkg/substitution"
@@ -62,7 +63,7 @@ func (we *WhenExpression) isTrue() bool {
 }
 
 func (we *WhenExpression) applyReplacements(replacements map[string]string, arrayReplacements map[string][]string) WhenExpression {
-	replacedInput := substitution.ApplyReplacements(we.Input, replacements)
+	replacedInput := applyReplacementsAsString(we.Input, replacements, arrayReplacements)
 	replacedCEL := substitution.ApplyReplacements(we.CEL, replacements)
 
 	var replacedValues []string
@@ -83,6 +84,26 @@ func (we *WhenExpression) applyReplacements(replacements map[string]string, arra
 	return WhenExpression{Input: replacedInput, Operator: we.Operator, Values: replacedValues, CEL: replacedCEL}
 }
 
+func applyReplacementsAsString(s string, replacements map[string]string, arrayReplacements map[string][]string) string {
+	if _, ok := arrayReplacements[fmt.Sprintf("%s.%s", ParamsPrefix, ArrayReference(s))]; ok {
+		b, err := json.Marshal(substitution.ApplyArrayReplacements(s, replacements, arrayReplacements))
+		if err != nil {
+			return s
+		}
+		return string(b)
+	}
+
+	if _, ok := arrayReplacements[ResultsArrayReference(s)]; ok {
+		b, err := json.Marshal(substitution.ApplyArrayReplacements(s, replacements, arrayReplacements))
+		if err != nil {
+			return s
+		}
+		return string(b)
+	}
+
+	return substitution.ApplyReplacements(s, replacements)
+}
+
 // GetVarSubstitutionExpressions extracts all the values between "$(" and ")" in a When Expression
 func (we *WhenExpression) GetVarSubstitutionExpressions() ([]string, bool) {
 	var allExpressions []string

pkg/apis/pipeline/v1/when_types_test.go

@@ -371,7 +371,69 @@ func TestApplyReplacements(t *testing.T) {
 			Operator: selection.In,
 			Values:   []string{"dev", "stage", "foo.txt", "readme.md", "test.go"},
 		},
-	}}
+	}, {
+		name: "replace input with empty results array",
+		original: &WhenExpression{
+			Input:    "$(tasks.foo.results.bar[*])",
+			Operator: selection.In,
+			Values:   []string{"main"},
+		},
+		arrayReplacements: map[string][]string{
+			"tasks.foo.results.bar": {},
+		},
+		expected: &WhenExpression{
+			Input:    "[]",
+			Operator: selection.In,
+			Values:   []string{"main"},
+		},
+	}, {
+		name: "replace input with non-empty results array",
+		original: &WhenExpression{
+			Input:    "$(tasks.foo.results.bar[*])",
+			Operator: selection.In,
+			Values:   []string{"main"},
+		},
+		arrayReplacements: map[string][]string{
+			"tasks.foo.results.bar": {"main", "devel"},
+		},
+		expected: &WhenExpression{
+			Input:    `["main","devel"]`,
+			Operator: selection.In,
+			Values:   []string{"main"},
+		},
+	},
+		{
+			name: "replace input with empty params array",
+			original: &WhenExpression{
+				Input:    "$(params.branches[*])",
+				Operator: selection.In,
+				Values:   []string{"main"},
+			},
+			arrayReplacements: map[string][]string{
+				"params.branches": {},
+			},
+			expected: &WhenExpression{
+				Input:    "[]",
+				Operator: selection.In,
+				Values:   []string{"main"},
+			},
+		},
+		{
+			name: "replace input with non-empty params array",
+			original: &WhenExpression{
+				Input:    "$(params.branches[*])",
+				Operator: selection.In,
+				Values:   []string{"main"},
+			},
+			arrayReplacements: map[string][]string{
+				"params.branches": {"main", "devel"},
+			},
+			expected: &WhenExpression{
+				Input:    `["main","devel"]`,
+				Operator: selection.In,
+				Values:   []string{"main"},
+			},
+		}}
 	for _, tc := range tests {
 		t.Run(tc.name, func(t *testing.T) {
 			got := tc.original.applyReplacements(tc.replacements, tc.arrayReplacements)