Support exists in assert for Dotty

Author: liufengyun

scalactic.dotty/src/main/scala/org/scalactic/BooleanMacro.scala

@@ -33,6 +33,33 @@ object BooleanMacro {
       case _ => false
     }
 
+    // use in `exists(_ == e)` or `exists(e == _)`
+    //
+    // Note: Scala2 implementation implicitly assumes `e` is side effect free,
+    //       we do the same. A better approach would be to check `e` is Ident or
+    //       Literal.
+    //
+    // {
+    //   def $anonfun(_$12: Int): Boolean = _$12.==(2)
+    //   closure($anonfun)
+    // }
+    object AnonFunction {
+      def unapply(t: Term): Option[Term] = t match {
+        case Block(
+          ddef @
+            DefDef(_, Nil, (ValDef(name, _, _) :: Nil) :: Nil, _,
+              Some(Apply(Select(lhs, "=="), rhs :: Nil))
+            ) :: Nil,
+          clos
+        ) if (clos.tpe.isFunctionType) => // walkaround: https://github.com/lampepfl/dotty/issues/6720
+          (lhs, rhs) match {
+            case (Ident(refName), _) if refName == name => Some(rhs)
+            case (_, Ident(refName)) if refName == name => Some(lhs)
+            case _ => None
+          }
+        case _ => None
+      }
+    }
 
     condition.unseal.underlyingArgument match {
       case Apply(sel @ Select(Apply(qual, lhs :: Nil), op @ ("===" | "!==")), rhs :: Nil) =>
@@ -115,6 +142,21 @@ object BooleanMacro {
               case _ =>
                 binaryDefault
             }
+          case "exists" =>
+            rhs match {
+              case AnonFunction(rhsInner) => // see the assumption for `rhsInner` in `AnonFunction`
+                let(lhs) { left =>
+                  val app = left.select(sel.symbol).appliedTo(rhs)
+                  let(app) { result =>
+                    val l = left.seal
+                    val r = rhsInner.seal
+                    val res = result.seal.cast[Boolean]
+                    val code = '{ Bool.existsMacroBool($l, $r, $res, $prettifier) }
+                    code.unseal
+                  }
+                }.seal.cast[Bool]
+              case _ => defaultCase
+            }
           case _ =>
             binaryDefault
         }

scalatest-test/src/test/scala/org/scalatest/AssertionsSpec.scala

@@ -1623,7 +1623,6 @@ class AssertionsSpec extends AnyFunSpec {
       assert(e.failedCodeLineNumber == (Some(thisLineNumber - 4)))
     }
 
-    // SKIP-DOTTY-START
     it("should do nothing when is used to check l1.exists(_ == 3)") {
       assert(l1.exists(_ == 3))
     }
@@ -1650,7 +1649,6 @@ class AssertionsSpec extends AnyFunSpec {
       assert(e.failedCodeFileName == (Some(fileName)))
       assert(e.failedCodeLineNumber == (Some(thisLineNumber - 4)))
     }
-    // SKIP-DOTTY-END
 
     it("should do nothing when is used to check !l1.exists(_ == 5)") {
       assert(!l1.exists(_ == 5))
@@ -1659,8 +1657,7 @@ class AssertionsSpec extends AnyFunSpec {
     it("should do nothing when is used to check !l1.exists(5 == _)") {
       assert(!l1.exists(5 == _))
     }
-    // SKIP-DOTTY-START
-    // TODO: better handle exists
+
     it("should throw TestFailedException with correct message and stack depth when is used to check !l1.exists(_ == 3)") {
       val e = intercept[TestFailedException] {
         assert(!l1.exists(_ == 3))
@@ -1679,6 +1676,8 @@ class AssertionsSpec extends AnyFunSpec {
       assert(e.failedCodeLineNumber == (Some(thisLineNumber - 4)))
     }
 
+    // SKIP-DOTTY-START
+    // different printing of anonymous functions
     it("should throw TestFailedException with correct message and stack depth when is used to check l1.exists(_ > 3)") {
       val e = intercept[TestFailedException] {
         assert(l1.exists(_ > 3))
@@ -1705,6 +1704,7 @@ class AssertionsSpec extends AnyFunSpec {
       assert(e.failedCodeFileName == (Some(fileName)))
       assert(e.failedCodeLineNumber == (Some(thisLineNumber - 4)))
     }
+    // SKIP-DOTTY-END
 
     it("should throw TestFailedException with correct message and stack depth when is used to check l3.exists(false)") {
       val e = intercept[TestFailedException] {
@@ -1714,7 +1714,6 @@ class AssertionsSpec extends AnyFunSpec {
       assert(e.failedCodeFileName == (Some(fileName)))
       assert(e.failedCodeLineNumber == (Some(thisLineNumber - 4)))
     }
-    // SKIP-DOTTY-END
 
     def woof(f: => Unit) = "woof"
     def meow(x: Int = 0, y: Int = 3) = "meow"
@@ -4549,8 +4548,6 @@ class AssertionsSpec extends AnyFunSpec {
       assert(e.failedCodeLineNumber == (Some(thisLineNumber - 4)))
     }
 
-    // SKIP-DOTTY-START
-    // missing support for exists
     it("should do nothing when is used to check l1.exists(_ == 3)") {
       assume(l1.exists(_ == 3))
     }
@@ -4603,6 +4600,8 @@ class AssertionsSpec extends AnyFunSpec {
       assert(e.failedCodeLineNumber == (Some(thisLineNumber - 4)))
     }
 
+    // SKIP-DOTTY-START
+    // different printing of anonymous function
     it("should throw TestCanceledException with correct message and stack depth when is used to check l1.exists(_ > 3)") {
       val e = intercept[TestCanceledException] {
         assume(l1.exists(_ > 3))
@@ -4629,6 +4628,7 @@ class AssertionsSpec extends AnyFunSpec {
       assert(e.failedCodeFileName == (Some(fileName)))
       assert(e.failedCodeLineNumber == (Some(thisLineNumber - 4)))
     }
+    // SKIP-DOTTY-END
 
     it("should throw TestCanceledException with correct message and stack depth when is used to check l3.exists(false)") {
       val e = intercept[TestCanceledException] {
@@ -4638,7 +4638,6 @@ class AssertionsSpec extends AnyFunSpec {
       assert(e.failedCodeFileName == (Some(fileName)))
       assert(e.failedCodeLineNumber == (Some(thisLineNumber - 4)))
     }
-    // SKIP-DOTTY-END
 
     def woof(f: => Unit) = "woof"
     def meow(x: Int = 0, y: Int = 3) = "meow"
@@ -6012,8 +6011,6 @@ class AssertionsSpec extends AnyFunSpec {
       assert(e.failedCodeLineNumber == (Some(thisLineNumber - 4)))
     }
 
-    // SKIP-DOTTY-START
-    // missing support for exists
     it("should do nothing when is used to check l1.exists(_ == 3)") {
       assume(l1.exists(_ == 3), ", dude")
     }
@@ -6066,6 +6063,8 @@ class AssertionsSpec extends AnyFunSpec {
       assert(e.failedCodeLineNumber == (Some(thisLineNumber - 4)))
     }
 
+    // SKIP-DOTTY-START
+    // different printing for anonymous functions
     it("should throw TestCanceledException with correct message and stack depth when is used to check l1.exists(_ > 3)") {
       val e = intercept[TestCanceledException] {
         assume(l1.exists(_ > 3), ", dude")
@@ -6092,6 +6091,7 @@ class AssertionsSpec extends AnyFunSpec {
       assert(e.failedCodeFileName == (Some(fileName)))
       assert(e.failedCodeLineNumber == (Some(thisLineNumber - 4)))
     }
+    // SKIP-DOTTY-END
 
     it("should throw TestCanceledException with correct message and stack depth when is used to check l3.exists(false)") {
       val e = intercept[TestCanceledException] {
@@ -6101,7 +6101,6 @@ class AssertionsSpec extends AnyFunSpec {
       assert(e.failedCodeFileName == (Some(fileName)))
       assert(e.failedCodeLineNumber == (Some(thisLineNumber - 4)))
     }
-    // SKIP-DOTTY-END
 
     def woof(f: => Unit) = "woof"
     def meow(x: Int = 0, y: Int = 3) = "meow"