diff --git a/server/src/main/java/de/zalando/zally/util/OpenApiUtil.kt b/server/src/main/java/de/zalando/zally/util/OpenApiUtil.kt
index c73c34c65..67cb12055 100644
--- a/server/src/main/java/de/zalando/zally/util/OpenApiUtil.kt
+++ b/server/src/main/java/de/zalando/zally/util/OpenApiUtil.kt
@@ -22,7 +22,7 @@ fun OpenAPI.getAllHeaders(): Set<HeaderElement> {
         .map { HeaderElement(it.key, it.value) }
         .toSet()
 
-    val fromComponentsParams = components.parameters.orEmpty().values.extractHeaders()
+    val fromComponentsParams = components?.parameters.orEmpty().values.extractHeaders()
 
     val fromPaths = paths.orEmpty().flatMap { (_, path) ->
         val fromPathParameters = path.parameters.extractHeaders()
@@ -34,7 +34,7 @@ fun OpenAPI.getAllHeaders(): Set<HeaderElement> {
         fromPathParameters + fromOperations
     }
 
-    val fromComponentsHeaders = components.headers.orEmpty().map { HeaderElement(it.key, it.value) }
+    val fromComponentsHeaders = components?.headers.orEmpty().map { HeaderElement(it.key, it.value) }
 
     return fromComponentsParams + fromPaths + fromComponentsHeaders
 }
@@ -43,9 +43,9 @@ fun OpenAPI.getAllHeaders(): Set<HeaderElement> {
  * Returns all defined schemas of an API specification
  * @return a collection of schemas
  */
-fun OpenAPI.getAllSchemas(): Collection<Schema<Any>> = this.components.schemas.orEmpty().values +
-    this.components.responses.values.flatMap { it.content.values.mapNotNull { it.schema } } +
-    this.components.requestBodies.values.flatMap { it.content.values.mapNotNull { it.schema } } +
+fun OpenAPI.getAllSchemas(): Collection<Schema<Any>> = this.components?.schemas.orEmpty().values +
+    this.components?.responses.orEmpty().values.flatMap { it.content.orEmpty().values.mapNotNull { it.schema } } +
+    this.components?.requestBodies.orEmpty().values.flatMap { it.content.orEmpty().values.mapNotNull { it.schema } } +
     this.paths.orEmpty().flatMap {
         it.value.readOperations().flatMap { it.parameters.orEmpty().mapNotNull { it.schema } }
     } +
@@ -109,7 +109,7 @@ fun OpenAPI.getAllProperties(): Map<String, Schema<Any>> {
  * Returns all defined parameters of an API specification
  * @return a collection of parameters
  */
-fun OpenAPI.getAllParameters(): Map<String, Parameter> = this.components.parameters.orEmpty() +
+fun OpenAPI.getAllParameters(): Map<String, Parameter> = this.components?.parameters.orEmpty() +
     this.paths.orEmpty().values.flatMap { it.parameters.orEmpty().mapNotNull { it.name to it } } +
     this.paths.orEmpty().values.flatMap {
         it.readOperations()
diff --git a/server/src/test/java/de/zalando/zally/util/OpenApiUtilTest.kt b/server/src/test/java/de/zalando/zally/util/OpenApiUtilTest.kt
index 3ba2c365d..99315174d 100644
--- a/server/src/test/java/de/zalando/zally/util/OpenApiUtilTest.kt
+++ b/server/src/test/java/de/zalando/zally/util/OpenApiUtilTest.kt
@@ -1,26 +1,334 @@
 package de.zalando.zally.util
 
+import io.swagger.v3.oas.models.Components
+import io.swagger.v3.oas.models.OpenAPI
+import io.swagger.v3.oas.models.Operation
+import io.swagger.v3.oas.models.PathItem
+import io.swagger.v3.oas.models.Paths
+import io.swagger.v3.oas.models.headers.Header
+import io.swagger.v3.oas.models.media.Content
+import io.swagger.v3.oas.models.media.MediaType
+import io.swagger.v3.oas.models.media.Schema
+import io.swagger.v3.oas.models.parameters.Parameter
+import io.swagger.v3.oas.models.parameters.RequestBody
+import io.swagger.v3.oas.models.responses.ApiResponse
+import io.swagger.v3.oas.models.responses.ApiResponses
 import org.junit.Test
+import org.assertj.core.api.Assertions.assertThat
 
 class OpenApiUtilTest {
 
     @Test
     fun `getAllHeaders should return headers from components parameters`() {
+        val api = OpenAPI().apply {
+            components = Components().apply {
+                parameters = mapOf("User-Agent" to Parameter().apply {
+                    `in` = "header"
+                    name = "User-Agent"
+                })
+            }
+        }
 
+        val headers = api.getAllHeaders()
+
+        assertThat(headers).isNotNull
+        assertThat(headers).hasSize(1)
     }
 
     @Test
     fun `getAllHeaders should return headers from paths`() {
+        val api = OpenAPI().apply {
+            val paths = Paths()
+            val pathItem = PathItem()
+            pathItem.get = Operation().apply {
+                parameters = listOf(Parameter().apply {
+                    `in` = "header"
+                    name = "User-Agent"
+                })
+            }
+            paths.addPathItem("path", pathItem)
+
+            this.paths = paths
+        }
+
+        val headers = api.getAllHeaders()
+
+        assertThat(headers).isNotNull
+        assertThat(headers).hasSize(1)
+    }
+
+    @Test
+    fun `getAllHeaders should return headers from components`() {
+        val api = OpenAPI().apply {
+            components = Components().apply {
+                headers = mapOf("User-Agent" to Header())
+            }
+        }
+
+        val headers = api.getAllHeaders()
+
+        assertThat(headers).isNotNull
+        assertThat(headers).hasSize(1)
+    }
+
+    @Test
+    fun `getAllHeaders should return empty set if no headers specified`() {
+        val api = OpenAPI()
+
+        val headers = api.getAllHeaders()
+
+        assertThat(headers).isNotNull
+        assertThat(headers).isEmpty()
+    }
+
+    @Test
+    fun `getAllSchemas should return component schemas`() {
+        val api = OpenAPI().apply {
+            components = Components().apply {
+                schemas = mapOf("pet" to Schema<String>())
+            }
+        }
+
+        val schemas = api.getAllSchemas()
+
+        assertThat(schemas).isNotNull
+        assertThat(schemas).hasSize(1)
+    }
+
+    @Test
+    fun `getAllSchemas should return component response schemas`() {
+        val api = OpenAPI().apply {
+            components = Components().apply {
+                responses = mapOf("response" to ApiResponse().apply {
+                    schemas = mapOf("pet" to Schema<String>())
+                })
+            }
+        }
+
+        val schemas = api.getAllSchemas()
+
+        assertThat(schemas).isNotNull
+        assertThat(schemas).hasSize(1)
+    }
+
+    @Test
+    fun `getAllSchemas should return component request body schemas`() {
+        val api = OpenAPI().apply {
+            components = Components().apply {
+                requestBodies = mapOf("request" to RequestBody().apply {
+                    schemas = mapOf("pet" to Schema<String>())
+                })
+            }
+        }
+
+        val schemas = api.getAllSchemas()
+
+        assertThat(schemas).isNotNull
+        assertThat(schemas).hasSize(1)
+    }
+
+    @Test
+    fun `getAllSchemas should return operation parameter schemas`() {
+        val api = OpenAPI().apply {
+            val paths = Paths()
+            val pathItem = PathItem()
+            pathItem.get = Operation().apply {
+                parameters = listOf(Parameter().apply {
+                    `in` = "body"
+                    schema = Schema<String>()
+                })
+            }
+            paths.addPathItem("path", pathItem)
+            this.paths = paths
+        }
+
+        val schemas = api.getAllSchemas()
+
+        assertThat(schemas).isNotNull
+        assertThat(schemas).hasSize(1)
+    }
+
+    @Test
+    fun `getAllSchemas should return operation response schemas`() {
+        val api = OpenAPI().apply {
+            val paths = Paths()
+            val pathItem = PathItem()
+            pathItem.get = Operation().apply {
+                val responses = ApiResponses()
+                responses.addApiResponse("response", ApiResponse().apply {
+                    val content = Content()
+                    content.addMediaType("application/json", MediaType().apply {
+                        schema = Schema<String>()
+                    })
+                    this.content = content
+                })
+                this.responses = responses
+            }
+            paths.addPathItem("path", pathItem)
+            this.paths = paths
+        }
+
+        val schemas = api.getAllSchemas()
+
+        assertThat(schemas).isNotNull
+        assertThat(schemas).hasSize(1)
+    }
 
+    @Test
+    fun `getAllSchemas should return operation request body schemas`() {
+        val api = OpenAPI().apply {
+            val paths = Paths()
+            val pathItem = PathItem()
+            pathItem.get = Operation().apply {
+                requestBody = RequestBody().apply {
+                    val content = Content()
+                    content.addMediaType("application/json", MediaType().apply {
+                        schema = Schema<String>()
+                    })
+                    this.content = content
+                }
+            }
+            paths.addPathItem("path", pathItem)
+            this.paths = paths
+        }
+
+        val schemas = api.getAllSchemas()
+
+        assertThat(schemas).isNotNull
+        assertThat(schemas).hasSize(1)
+    }
+
+    @Test
+    fun `getAllSchemas should return an empty collection if no schemas are specified`() {
+        val api = OpenAPI()
+
+        val schemas = api.getAllSchemas()
+
+        assertThat(schemas).isNotNull
+        assertThat(schemas).isEmpty()
+    }
+
+    @Test
+    fun `getAllTransitiveSchemas should return a set of all schemas`() {
+        val api = OpenAPI().apply {
+            components = Components().apply {
+                schemas = mapOf("pet" to Schema<Any>().apply {
+                    title = "pet"
+                    properties = mapOf(
+                        "name" to Schema<String>().apply { title = "name" },
+                        "age" to Schema<Int>().apply { title = "age" }
+                    )
+                })
+            }
+        }
+
+        val schemas = api.getAllTransitiveSchemas()
+
+        assertThat(schemas).isNotNull
+        assertThat(schemas).hasSize(2)
+    }
+
+    @Test
+    fun `getAllTransitiveSchemas should return an empty set if no schemas are specified`() {
+        val api = OpenAPI()
+
+        val schemas = api.getAllTransitiveSchemas()
+
+        assertThat(schemas).isNotNull
+        assertThat(schemas).isEmpty()
+    }
+
+    @Test
+    fun `getAllProperties should return a map of all properties`() {
+        val api = OpenAPI().apply {
+            components = Components().apply {
+                schemas = mapOf("pet" to Schema<Any>().apply {
+                    title = "pet"
+                    properties = mapOf(
+                        "name" to Schema<String>().apply { title = "name" },
+                        "age" to Schema<Int>().apply { title = "age" }
+                    )
+                })
+            }
+        }
+
+        val schemas = api.getAllProperties()
+
+        assertThat(schemas).isNotNull
+        assertThat(schemas).hasSize(2)
+    }
+
+    @Test
+    fun `getAllProperties should return an empty set if no properties are specified`() {
+        val api = OpenAPI()
+
+        val schemas = api.getAllProperties()
+
+        assertThat(schemas).isNotNull
+        assertThat(schemas).isEmpty()
+    }
+
+    @Test
+    fun `getAllParameters should return components parameters`() {
+        val api = OpenAPI().apply {
+            components = Components().apply {
+                parameters = mapOf("pet" to Parameter().apply {
+                    name = "name"
+                })
+            }
+        }
+
+        val schemas = api.getAllParameters()
+
+        assertThat(schemas).isNotNull
+        assertThat(schemas).hasSize(1)
+    }
+
+    @Test
+    fun `getAllParameters should return paths parameters`() {
+        val api = OpenAPI().apply {
+            val paths = Paths()
+            val pathItem = PathItem()
+            pathItem.parameters = listOf(Parameter().apply {
+                name = "name"
+            })
+            paths.addPathItem("path", pathItem)
+            this.paths = paths
+        }
+
+        val schemas = api.getAllParameters()
+
+        assertThat(schemas).isNotNull
+        assertThat(schemas).hasSize(1)
     }
 
     @Test
-    fun `getAllHeaders should return headers from compoents`() {
+    fun `getAllParameters should return path operation parameters`() {
+        val api = OpenAPI().apply {
+            val paths = Paths()
+            val pathItem = PathItem()
+            pathItem.get = Operation().apply {
+                parameters = listOf(Parameter().apply {
+                    name = "name"
+                })
+            }
+            paths.addPathItem("path", pathItem)
+            this.paths = paths
+        }
 
+        val schemas = api.getAllParameters()
+
+        assertThat(schemas).isNotNull
+        assertThat(schemas).hasSize(1)
     }
 
     @Test
-    fun `getAllHeaders should `() {
+    fun `getAllParameters should return an empty map if no parameters are specified`() {
+        val api = OpenAPI()
+
+        val schemas = api.getAllParameters()
 
+        assertThat(schemas).isNotNull
+        assertThat(schemas).isEmpty()
     }
 }
\ No newline at end of file