Add Assert<StateFlow>.value()

CHANGELOG.md

@@ -14,6 +14,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - signature of `isIn` and `isNotIn` has been changed to ensure at least two items are supplied.
 - added assertions `isIn(Iterable<T>)` and `isNotIn(Iterable<T>)`
 
+### Added
+- `havingValue` for `StateFlow` assertions
+
 ## [0.28.1] 2024-04-17
 
 ### Added

assertk-coroutines/src/commonMain/kotlin/assertk/coroutines/assertions/flow.kt

@@ -11,6 +11,16 @@ import kotlinx.coroutines.flow.*
 
 suspend fun Assert<Flow<*>>.count(): Assert<Int> = having("count()", Flow<*>::count)
 
+/**
+ * Returns an assert that asserts on the value of the given [StateFlow]
+ *
+ * ```
+ * val person: StateFlow<Person> = _person
+ * assertThat(person).havingValue().having(Person::name).isEqualTo("Sue")
+ * ```
+ */
+fun <T> Assert<StateFlow<T>>.havingValue() = having(StateFlow<T>::value)
+
 /**
  * Asserts the flow is empty. Fails as soon as the flow delivers an element.
  * @see isNotEmpty

assertk-coroutines/src/commonTest/kotlin/test/assertk/coroutines/assertions/FlowTest.kt

@@ -1,9 +1,11 @@
 package test.assertk.coroutines.assertions
 
 import assertk.assertThat
+import assertk.assertions.isEqualTo
 import assertk.assertions.support.show
 import assertk.coroutines.assertions.*
 import kotlinx.coroutines.channels.awaitClose
+import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.callbackFlow
 import kotlinx.coroutines.flow.flowOf
 import kotlin.test.Test
@@ -307,6 +309,18 @@ class FlowTest {
         )
     }
     //endregion
+
+    //region StateFlow value
+    @Test
+    fun value_transform() {
+        val name = MutableStateFlow("Sue")
+        val display = name::class.simpleName!!
+        val error = assertFailsWith<AssertionError> {
+            assertThat(name, "name") { display }.havingValue().isEqualTo("John")
+        }
+        assertEquals("""expected [name.value]:<"[John]"> but was:<"[Sue]"> ($display)""", error.message)
+    }
+    //endregion
 }
 
 private fun <T> nonCompletingFlowOf(vararg elements: T) = callbackFlow {