Use correct subject description when using with passing a lambda

strikt-core/src/main/kotlin/strikt/api/Assertion.kt

@@ -217,7 +217,8 @@ interface Assertion {
      * @return an assertion builder whose subject is the value returned by
      * [function].
      */
-    fun <R> get(function: T.() -> R): DescribeableBuilder<R> = get(function.describe(), function)
+    fun <R> get(function: T.() -> R): DescribeableBuilder<R> =
+      get(function.describe("get"), function)
 
     /**
      * Runs a group of assertions on the subject returned by [function].
@@ -247,7 +248,7 @@ interface Assertion {
     fun <R> with(
       function: T.() -> R,
       block: Builder<R>.() -> Unit
-    ) = with(function.describe(), function, block)
+    ) = with(function.describe("with"), function, block)
 
     /**
      * Maps the assertion subject to the result of [function].
@@ -319,17 +320,17 @@ interface Assertion {
   }
 }
 
-private fun <Receiver, Result> (Receiver.() -> Result).describe(): String =
+private fun <Receiver, Result> (Receiver.() -> Result).describe(name: String): String =
   when (this) {
     is KProperty<*> ->
-      "value of property $name"
+      "value of property ${this.name}"
     is KFunction<*> ->
-      "return value of $name"
+      "return value of ${this.name}"
     is CallableReference -> "value of $propertyName"
     else -> {
       try {
         val line = FilePeek.filePeek.getCallerFileInfo().line
-        LambdaBody("get", line).body.trim()
+        LambdaBody(name, line).body.trim()
       } catch (e: Exception) {
         "%s"
       }

strikt-core/src/test/kotlin/strikt/Formatting.kt

@@ -1,6 +1,7 @@
 package strikt
 
 import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Nested
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.assertThrows
 import strikt.api.expectThat
@@ -12,6 +13,7 @@ import strikt.assertions.isNotEqualTo
 import strikt.assertions.isNotNull
 import strikt.assertions.isUpperCase
 import strikt.assertions.startsWith
+import java.time.LocalDate
 
 @DisplayName("error message formatting")
 internal class Formatting {
@@ -175,4 +177,96 @@ internal class Formatting {
       """.trimMargin()
     )
   }
+
+  @Nested
+  @DisplayName("subject description")
+  inner class SubjectDescription {
+    @Nested
+    @DisplayName("when using get")
+    inner class Get {
+      @Test
+      fun `is the property name when passing a lambda`() {
+        val subject = Person("David", LocalDate.of(1947, 1, 8))
+
+        val error = assertThrows<AssertionError> {
+          expectThat(subject).get { birthDate }
+            .get(LocalDate::getYear)
+            .isEqualTo(1971)
+        }
+
+        expectThat(error.message).isEqualTo(
+          """▼ Expect that Person(name=David, birthDate=1947-01-08):
+          |  ▼ birthDate:
+          |    ▼ return value of getYear:
+          |      ✗ is equal to 1971
+          |              found 1947""".trimMargin()
+        )
+      }
+
+      @Test
+      fun `is the property name when passing a property`() {
+        val subject = Person("David", LocalDate.of(1947, 1, 8))
+
+        val error = assertThrows<AssertionError> {
+          expectThat(subject).get(Person::birthDate)
+            .get(LocalDate::getYear)
+            .isEqualTo(1971)
+        }
+
+        expectThat(error.message).isEqualTo(
+          """▼ Expect that Person(name=David, birthDate=1947-01-08):
+          |  ▼ value of property birthDate:
+          |    ▼ return value of getYear:
+          |      ✗ is equal to 1971
+          |              found 1947""".trimMargin()
+        )
+      }
+    }
+
+    @Nested
+    @DisplayName("when using with")
+    inner class With {
+      @Test
+      fun `is the property name when passing a lambda`() {
+        val subject = Person("David", LocalDate.of(1947, 1, 8))
+
+        val error = assertThrows<AssertionError> {
+          expectThat(subject) {
+            with({ birthDate }) {
+              get { year }.isEqualTo(1971)
+            }
+          }
+        }
+
+        expectThat(error.message).isEqualTo(
+          """▼ Expect that Person(name=David, birthDate=1947-01-08):
+          |  ▼ birthDate:
+          |    ▼ year:
+          |      ✗ is equal to 1971
+          |              found 1947""".trimMargin()
+        )
+      }
+
+      @Test
+      fun `is property name when passing a property`() {
+        val subject = Person("David", LocalDate.of(1947, 1, 8))
+
+        val error = assertThrows<AssertionError> {
+          expectThat(subject) {
+            with(Person::birthDate) {
+              get { year }.isEqualTo(1971)
+            }
+          }
+        }
+
+        expectThat(error.message).isEqualTo(
+          """▼ Expect that Person(name=David, birthDate=1947-01-08):
+          |  ▼ value of property birthDate:
+          |    ▼ year:
+          |      ✗ is equal to 1971
+          |              found 1947""".trimMargin()
+        )
+      }
+    }
+  }
 }