Map entry mapping function

Fixes #45
robfletcher · Jun 5, 2018 · 7e77f65 · 7e77f65
1 parent 23b2367
commit 7e77f65
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Showing 2 changed files with 14 additions and 1 deletion.
diff --git a/strikt-core/src/main/kotlin/strikt/assertions/Map.kt b/strikt-core/src/main/kotlin/strikt/assertions/Map.kt
@@ -3,4 +3,7 @@ package strikt.assertions
 import strikt.api.Assertion
 
 fun <T : Map<K, V>, K, V> Assertion<T>.isEmpty() =
-  passesIf("is empty") { isEmpty() }
+  passesIf("is empty") { isEmpty() }
+
+operator fun <T : Map<K, V>, K, V> Assertion<T>.get(key: K): Assertion<V?> =
+  map("entry [$key] %s") { get(key) }
diff --git a/strikt-core/src/test/kotlin/strikt/Mapping.kt b/strikt-core/src/test/kotlin/strikt/Mapping.kt
@@ -9,6 +9,8 @@ import strikt.assertions.containsExactly
 import strikt.assertions.first
 import strikt.assertions.get
 import strikt.assertions.isEqualTo
+import strikt.assertions.isNotNull
+import strikt.assertions.isNull
 import strikt.assertions.last
 import java.time.LocalDate
 
@@ -37,6 +39,14 @@ internal object Mapping : Spek({
         expect(subject)[1..2].containsExactly("rubberplant", "marzipan")
       }
     }
+
+    describe("mapping assertions on ${Map::class.java.simpleName}") {
+      it("maps to a value element using [key]") {
+        val subject = mapOf("foo" to "bar")
+        expect(subject)["foo"].isNotNull().isEqualTo("bar")
+        expect(subject)["bar"].isNull()
+      }
+    }
   }
 
   describe("custom mapping") {