fix(SpdxExpression): Fix license choice for mixed expressions

Recursively get the valid choices for the `left` an `right` parts of
`SodxCompoundExpression`s for the `AND` operator.

Signed-off-by: Marcel Bochtler <[email protected]>

Author: MarcelBochtler

utils/spdx/src/main/kotlin/SpdxExpression.kt

@@ -310,24 +310,29 @@ class SpdxCompoundExpression(
         right.validate(strictness)
     }
 
-    override fun validChoicesForDnf(): Set<SpdxExpression> =
-        when (operator) {
-            SpdxOperator.AND -> setOf(decompose().reduce(SpdxExpression::and))
-
-            SpdxOperator.OR -> {
-                val validChoicesLeft = when (left) {
-                    is SpdxCompoundExpression -> left.validChoicesForDnf()
-                    else -> left.validChoices()
-                }
+    override fun validChoicesForDnf(): Set<SpdxExpression> {
+        val validChoicesLeft = when (left) {
+            is SpdxCompoundExpression -> left.validChoicesForDnf()
+            else -> left.validChoices()
+        }
 
-                val validChoicesRight = when (right) {
-                    is SpdxCompoundExpression -> right.validChoicesForDnf()
-                    else -> right.validChoices()
-                }
+        val validChoicesRight = when (right) {
+            is SpdxCompoundExpression -> right.validChoicesForDnf()
+            else -> right.validChoices()
+        }
 
-                validChoicesLeft + validChoicesRight
+        return when (operator) {
+            SpdxOperator.AND -> {
+                validChoicesLeft.map { leftChoice ->
+                    validChoicesRight.map { rightChoice ->
+                        if (leftChoice == rightChoice) leftChoice else leftChoice and rightChoice
+                    }
+                }.flatten().toSet()
             }
+
+            SpdxOperator.OR -> validChoicesLeft + validChoicesRight
         }
+    }
 
     override fun offersChoice(): Boolean =
         when (operator) {

utils/spdx/src/test/kotlin/SpdxExpressionTest.kt

@@ -439,6 +439,15 @@ class SpdxExpressionTest : WordSpec() {
             "not contain duplicate valid choice different left and right expressions" {
                 "a AND a AND b".toSpdx().validChoices() should containExactly("a AND b".toSpdx())
             }
+
+            "return the correct choices for a mixed expression" {
+                val spdxExpression = "a AND (a OR b)".toSpdx()
+
+                spdxExpression.validChoices() should containExactlyInAnyOrder(
+                    "a".toSpdx(),
+                    "a AND b".toSpdx()
+                )
+            }
         }
 
         "offersChoice()" should {