diff --git a/tests/README.md b/tests/README.md
index 7a35cf07..97715af7 100644
--- a/tests/README.md
+++ b/tests/README.md
@@ -24,7 +24,7 @@ This folder contains test cases for the openEO processes.
 - [x] arctan
 - [x] arctan2
 - [x] array_append
-- [ ] array_apply
+- [x] array_apply
 - [x] array_concat
 - [x] array_contains
 - [x] array_create
@@ -226,6 +226,15 @@ properties:
             description: An argument, can be of any type
         returns:
           description: The return value, can be of any type
+        required:
+          description: >-
+            A list of processes that is required for this test (except for the process provided in `id`).
+            This is usually required for processes that run a sub-process (callback) so that the test suite can skip tests for processes that are not supported.
+          type: array
+          items:
+            type: string
+            description: The identifier for the sub-process.
+            pattern: '^\w+$'
         delta:
           description: If set to a positive number the equality of the actual return value and the expected return value is checked against a delta value to circumvent problems with floating-point inaccuracy.
           type: number
diff --git a/tests/array_apply.json5 b/tests/array_apply.json5
index 19e56861..520c8cbb 100644
--- a/tests/array_apply.json5
+++ b/tests/array_apply.json5
@@ -1,4 +1,338 @@
 {
   "id": "array_apply",
-  "tests": []
-}
\ No newline at end of file
+  "tests": [
+    {
+      // empty array
+      "required": [
+        "absolute"
+      ],
+      "arguments": {
+        "data": [],
+        "process": {
+          "process_graph": {
+            "absolute": {
+              "process_id": "absolute",
+              "arguments": {
+                "x": {
+                  "from_argument": "x"
+                }
+              },
+              "result": true
+            }
+          }
+        }
+      },
+      "returns": []
+    },
+    {
+      // single math process applied to a normal array
+      "required": [
+        "absolute"
+      ],
+      "arguments": {
+        "data": [
+          1,
+          -2,
+          3.5,
+          -4.725,
+          NaN
+        ],
+        "process": {
+          "process_graph": {
+            "absolute": {
+              "process_id": "absolute",
+              "arguments": {
+                "x": {
+                  "from_argument": "x"
+                }
+              },
+              "result": true
+            }
+          }
+        }
+      },
+      "returns": [
+          1,
+          2,
+          3.5,
+          4.725,
+          NaN
+      ]
+    },
+    {
+      // single math process applied to a normal array, with context parameter
+      "required": [
+        "multiply"
+      ],
+      "arguments": {
+        "data": [
+          1,
+          2.5
+        ],
+        "process": {
+          "process_graph": {
+            "absolute": {
+              "process_id": "multiply",
+              "arguments": {
+                "x": {
+                  "from_argument": "x"
+                },
+                "y": {
+                  "from_argument": "context"
+                }
+              },
+              "result": true
+            }
+          }
+        },
+        "context": 2.5
+      },
+      "returns": [
+          2.5,
+          6.25
+      ]
+    },
+    {
+      // single comparison process with datatype change applied to a normal array
+      "required": [
+        "gt"
+      ],
+      "arguments": {
+        "data": [
+          1,
+          -2,
+          3.5,
+          -4.725,
+          NaN
+        ],
+        "process": {
+          "process_graph": {
+            "gt": {
+              "process_id": "gt",
+              "arguments": {
+                "x": {
+                  "from_argument": "x"
+                },
+                "y": 3
+              },
+              "result": true
+            }
+          }
+        }
+      },
+      "returns": [
+          false,
+          false,
+          true,
+          true,
+          false
+      ]
+    },
+    {
+      // handle index from a normal array
+      "required": [
+        "constant"
+      ],
+      "arguments": {
+        "data": [
+          1,
+          2,
+          3,
+          4
+        ],
+        "process": {
+          "process_graph": {
+            "const": {
+              "process_id": "constant",
+              "arguments": {
+                "x": {
+                  "from_argument": "index"
+                }
+              },
+              "result": true
+            }
+          }
+        }
+      },
+      "returns": [
+          0,
+          1,
+          2,
+          3
+      ]
+    },
+    {
+      // handle label from a labeled array
+      "required": [
+        "constant"
+      ],
+      "arguments": {
+        "data": {
+          "type": "labeled-array",
+          "data": [
+            {
+              "key": "B01",
+              "value": 1.23
+            },
+            {
+              "key": "B02",
+              "value": 0.98
+            }
+          ]
+        },
+        "process": {
+          "process_graph": {
+            "const": {
+              "process_id": "constant",
+              "arguments": {
+                "x": {
+                  "from_argument": "label"
+                }
+              },
+              "result": true
+            }
+          }
+        }
+      },
+      "returns": [
+          "B01",
+          "B02"
+      ]
+    },
+    {
+      // handle index and value from a labeled array
+      "required": [
+        "add"
+      ],
+      "arguments": {
+        "data": {
+          "type": "labeled-array",
+          "data": [
+            {
+              "key": "B01",
+              "value": 1.23
+            },
+            {
+              "key": "B02",
+              "value": 0.98
+            }
+          ]
+        },
+        "process": {
+          "process_graph": {
+            "const": {
+              "process_id": "add",
+              "arguments": {
+                "x": {
+                  "from_argument": "index"
+                },
+                "y": {
+                  "from_argument": "x"
+                }
+              },
+              "result": true
+            }
+          }
+        }
+      },
+      "returns": [
+          1.23,
+          1.98
+      ]
+    },
+    {
+      // single math process applied to a labeled array
+      "required": [
+        "subtract"
+      ],
+      "arguments": {
+        "data": {
+          "type": "labeled-array",
+          "data": [
+            {
+              "key": "B01",
+              "value": 1.23
+            },
+            {
+              "key": "B02",
+              "value": 0.98
+            }
+          ]
+        },
+        "process": {
+          "process_graph": {
+            "const": {
+              "process_id": "subtract",
+              "arguments": {
+                "x": {
+                  "from_argument": "x"
+                },
+                "y": 1
+              },
+              "result": true
+            }
+          }
+        }
+      },
+      "returns": {
+        "type": "labeled-array",
+        "data": [
+          {
+            "key": "B01",
+            "value": 0.23
+          },
+          {
+            "key": "B02",
+            "value": -0.02
+          }
+        ]
+      }
+    },
+    {
+      // apply multiple math process to a labeled array
+      "required": [
+        "add",
+        "multiply"
+      ],
+      "arguments": {
+        "data": [
+          1,
+          -2,
+          3.5,
+          -4.725,
+          NaN
+        ],
+        "process": {
+          "process_graph": {
+            "add": {
+              "process_id": "add",
+              "arguments": {
+                "x": {
+                  "from_argument": "x"
+                },
+                "y": 1.5
+              }
+            },
+            "mulitply": {
+              "process_id": "mulitply",
+              "arguments": {
+                "x": {
+                  "from_node": "add"
+                },
+                "y": 2
+              },
+              "result": true
+            }
+          }
+        }
+      },
+      "returns": [
+          5,
+          -1,
+          10,
+          6.45,
+          NaN
+      ]
+    }
+  ]
+}
diff --git a/tests/eq.json5 b/tests/eq.json5
index b9eea31e..50898f5f 100644
--- a/tests/eq.json5
+++ b/tests/eq.json5
@@ -97,6 +97,20 @@
       },
       "returns": null
     },
+    {
+      "arguments": {
+        "x": 5,
+        "y": NaN
+      },
+      "returns": false
+    },
+    {
+      "arguments": {
+        "x": NaN,
+        "y": 5
+      },
+      "returns": false
+    },
     {
       "arguments": {
         "x": NaN,
@@ -119,4 +133,4 @@
       "returns": false
     }
   ]
-}
\ No newline at end of file
+}
diff --git a/tests/gt.json5 b/tests/gt.json5
index f799f161..651401e5 100644
--- a/tests/gt.json5
+++ b/tests/gt.json5
@@ -71,6 +71,20 @@
       },
       "returns": null
     },
+    {
+      "arguments": {
+        "x": 5,
+        "y": NaN
+      },
+      "returns": false
+    },
+    {
+      "arguments": {
+        "x": NaN,
+        "y": 5
+      },
+      "returns": false
+    },
     {
       "arguments": {
         "x": NaN,
diff --git a/tests/gte.json5 b/tests/gte.json5
index c513cf4f..34f58a1c 100644
--- a/tests/gte.json5
+++ b/tests/gte.json5
@@ -85,6 +85,20 @@
       },
       "returns": null
     },
+    {
+      "arguments": {
+        "x": 5,
+        "y": NaN
+      },
+      "returns": false
+    },
+    {
+      "arguments": {
+        "x": NaN,
+        "y": 5
+      },
+      "returns": false
+    },
     {
       "arguments": {
         "x": NaN,
diff --git a/tests/lt.json5 b/tests/lt.json5
index e298c02b..a3601197 100644
--- a/tests/lt.json5
+++ b/tests/lt.json5
@@ -71,6 +71,20 @@
       },
       "returns": null
     },
+    {
+      "arguments": {
+        "x": 5,
+        "y": NaN
+      },
+      "returns": false
+    },
+    {
+      "arguments": {
+        "x": NaN,
+        "y": 5
+      },
+      "returns": false
+    },
     {
       "arguments": {
         "x": NaN,
diff --git a/tests/lte.json5 b/tests/lte.json5
index 112735fc..b5f920c5 100644
--- a/tests/lte.json5
+++ b/tests/lte.json5
@@ -85,6 +85,20 @@
       },
       "returns": null
     },
+    {
+      "arguments": {
+        "x": 5,
+        "y": NaN
+      },
+      "returns": false
+    },
+    {
+      "arguments": {
+        "x": NaN,
+        "y": 5
+      },
+      "returns": false
+    },
     {
       "arguments": {
         "x": NaN,
diff --git a/tests/neq.json5 b/tests/neq.json5
index fd4e011e..dd837847 100644
--- a/tests/neq.json5
+++ b/tests/neq.json5
@@ -97,6 +97,20 @@
       },
       "returns": null
     },
+    {
+      "arguments": {
+        "x": 5,
+        "y": NaN
+      },
+      "returns": true
+    },
+    {
+      "arguments": {
+        "x": NaN,
+        "y": 5
+      },
+      "returns": true
+    },
     {
       "arguments": {
         "x": NaN,
@@ -119,4 +133,4 @@
       "returns": true
     }
   ]
-}
\ No newline at end of file
+}