test: extract null reading tests (#616)

src/commonTest/kotlin/com/charleskorn/kaml/YamlNullReadingTest.kt

@@ -0,0 +1,299 @@
+/*
+
+   Copyright 2018-2023 Charles Korn.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       https://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+
+*/
+
+package com.charleskorn.kaml
+
+import com.charleskorn.kaml.testobjects.TestEnum
+import io.kotest.assertions.asClue
+import io.kotest.assertions.throwables.shouldThrow
+import io.kotest.matchers.shouldBe
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.builtins.ListSerializer
+import kotlinx.serialization.builtins.nullable
+import kotlinx.serialization.builtins.serializer
+
+class YamlNullReadingTest : FlatFunSpec({
+    context("a YAML parser parsing null values") {
+        val input = "null"
+
+        context("parsing a null value as a nullable string") {
+            val result = Yaml.default.decodeFromString(String.serializer().nullable, input)
+
+            test("returns a null value") {
+                result shouldBe null
+            }
+        }
+
+        context("parsing a null value as a non-nullable string") {
+            test("throws an appropriate exception") {
+                val exception = shouldThrow<UnexpectedNullValueException> { Yaml.default.decodeFromString(String.serializer(), input) }
+
+                exception.asClue {
+                    it.message shouldBe "Unexpected null or empty value for non-null field."
+                    it.line shouldBe 1
+                    it.column shouldBe 1
+                    it.path shouldBe YamlPath.root
+                }
+            }
+        }
+
+        context("parsing a null value as a nullable integer") {
+            val result = Yaml.default.decodeFromString(Int.serializer().nullable, input)
+
+            test("returns a null value") {
+                result shouldBe null
+            }
+        }
+
+        context("parsing a null value as a non-nullable integer") {
+            test("throws an appropriate exception") {
+                val exception = shouldThrow<UnexpectedNullValueException> { Yaml.default.decodeFromString(Int.serializer(), input) }
+
+                exception.asClue {
+                    it.message shouldBe "Unexpected null or empty value for non-null field."
+                    it.line shouldBe 1
+                    it.column shouldBe 1
+                    it.path shouldBe YamlPath.root
+                }
+            }
+        }
+
+        context("parsing a null value as a nullable long") {
+            val result = Yaml.default.decodeFromString(Long.serializer().nullable, input)
+
+            test("returns a null value") {
+                result shouldBe null
+            }
+        }
+
+        context("parsing a null value as a non-nullable long") {
+            test("throws an appropriate exception") {
+                val exception = shouldThrow<UnexpectedNullValueException> { Yaml.default.decodeFromString(Long.serializer(), input) }
+
+                exception.asClue {
+                    it.message shouldBe "Unexpected null or empty value for non-null field."
+                    it.line shouldBe 1
+                    it.column shouldBe 1
+                    it.path shouldBe YamlPath.root
+                }
+            }
+        }
+
+        context("parsing a null value as a nullable short") {
+            val result = Yaml.default.decodeFromString(Short.serializer().nullable, input)
+
+            test("returns a null value") {
+                result shouldBe null
+            }
+        }
+
+        context("parsing a null value as a non-nullable short") {
+            test("throws an appropriate exception") {
+                val exception = shouldThrow<UnexpectedNullValueException> { Yaml.default.decodeFromString(Short.serializer(), input) }
+
+                exception.asClue {
+                    it.message shouldBe "Unexpected null or empty value for non-null field."
+                    it.line shouldBe 1
+                    it.column shouldBe 1
+                    it.path shouldBe YamlPath.root
+                }
+            }
+        }
+
+        context("parsing a null value as a nullable byte") {
+            val result = Yaml.default.decodeFromString(Byte.serializer().nullable, input)
+
+            test("returns a null value") {
+                result shouldBe null
+            }
+        }
+
+        context("parsing a null value as a non-nullable byte") {
+            test("throws an appropriate exception") {
+                val exception = shouldThrow<UnexpectedNullValueException> { Yaml.default.decodeFromString(Byte.serializer(), input) }
+
+                exception.asClue {
+                    it.message shouldBe "Unexpected null or empty value for non-null field."
+                    it.line shouldBe 1
+                    it.column shouldBe 1
+                    it.path shouldBe YamlPath.root
+                }
+            }
+        }
+
+        context("parsing a null value as a nullable double") {
+            val result = Yaml.default.decodeFromString(Double.serializer().nullable, input)
+
+            test("returns a null value") {
+                result shouldBe null
+            }
+        }
+
+        context("parsing a null value as a non-nullable double") {
+            test("throws an appropriate exception") {
+                val exception = shouldThrow<UnexpectedNullValueException> { Yaml.default.decodeFromString(Double.serializer(), input) }
+
+                exception.asClue {
+                    it.message shouldBe "Unexpected null or empty value for non-null field."
+                    it.line shouldBe 1
+                    it.column shouldBe 1
+                    it.path shouldBe YamlPath.root
+                }
+            }
+        }
+
+        context("parsing a null value as a nullable float") {
+            val result = Yaml.default.decodeFromString(Float.serializer().nullable, input)
+
+            test("returns a null value") {
+                result shouldBe null
+            }
+        }
+
+        context("parsing a null value as a non-nullable float") {
+            test("throws an appropriate exception") {
+                val exception = shouldThrow<UnexpectedNullValueException> { Yaml.default.decodeFromString(Float.serializer(), input) }
+
+                exception.asClue {
+                    it.message shouldBe "Unexpected null or empty value for non-null field."
+                    it.line shouldBe 1
+                    it.column shouldBe 1
+                    it.path shouldBe YamlPath.root
+                }
+            }
+        }
+
+        context("parsing a null value as a nullable boolean") {
+            val result = Yaml.default.decodeFromString(Boolean.serializer().nullable, input)
+
+            test("returns a null value") {
+                result shouldBe null
+            }
+        }
+
+        context("parsing a null value as a non-nullable boolean") {
+            test("throws an appropriate exception") {
+                val exception = shouldThrow<UnexpectedNullValueException> { Yaml.default.decodeFromString(Boolean.serializer(), input) }
+
+                exception.asClue {
+                    it.message shouldBe "Unexpected null or empty value for non-null field."
+                    it.line shouldBe 1
+                    it.column shouldBe 1
+                    it.path shouldBe YamlPath.root
+                }
+            }
+        }
+
+        context("parsing a null value as a nullable character") {
+            val result = Yaml.default.decodeFromString(Char.serializer().nullable, input)
+
+            test("returns a null value") {
+                result shouldBe null
+            }
+        }
+
+        context("parsing a null value as a non-nullable character") {
+            test("throws an appropriate exception") {
+                val exception = shouldThrow<UnexpectedNullValueException> { Yaml.default.decodeFromString(Char.serializer(), input) }
+
+                exception.asClue {
+                    it.message shouldBe "Unexpected null or empty value for non-null field."
+                    it.line shouldBe 1
+                    it.column shouldBe 1
+                    it.path shouldBe YamlPath.root
+                }
+            }
+        }
+
+        context("parsing a null value as a nullable enum") {
+            val result = Yaml.default.decodeFromString(TestEnum.serializer().nullable, input)
+
+            test("returns a null value") {
+                result shouldBe null
+            }
+        }
+
+        context("parsing a null value as a non-nullable enum") {
+            test("throws an appropriate exception") {
+                val exception = shouldThrow<UnexpectedNullValueException> { Yaml.default.decodeFromString(TestEnum.serializer(), input) }
+
+                exception.asClue {
+                    it.message shouldBe "Unexpected null or empty value for non-null field."
+                    it.line shouldBe 1
+                    it.column shouldBe 1
+                    it.path shouldBe YamlPath.root
+                }
+            }
+        }
+
+        context("parsing a null value as a nullable list") {
+            val result = Yaml.default.decodeFromString(ListSerializer(String.serializer()).nullable, input)
+
+            test("returns a null value") {
+                result shouldBe null
+            }
+        }
+
+        context("parsing a null value as a non-nullable list") {
+            test("throws an appropriate exception") {
+                val exception = shouldThrow<UnexpectedNullValueException> { Yaml.default.decodeFromString(ListSerializer(String.serializer()), input) }
+
+                exception.asClue {
+                    it.message shouldBe "Unexpected null or empty value for non-null field."
+                    it.line shouldBe 1
+                    it.column shouldBe 1
+                    it.path shouldBe YamlPath.root
+                }
+            }
+        }
+
+        @Serializable
+        class ComplexStructureForNull
+
+        context("parsing a null value as a nullable object") {
+            val result = Yaml.default.decodeFromString(ComplexStructureForNull.serializer().nullable, input)
+
+            test("returns a null value") {
+                result shouldBe null
+            }
+        }
+
+        context("parsing a null value as a non-nullable object") {
+            test("throws an appropriate exception") {
+                val exception = shouldThrow<UnexpectedNullValueException> { Yaml.default.decodeFromString(ComplexStructureForNull.serializer(), input) }
+
+                exception.asClue {
+                    it.message shouldBe "Unexpected null or empty value for non-null field."
+                    it.line shouldBe 1
+                    it.column shouldBe 1
+                    it.path shouldBe YamlPath.root
+                }
+            }
+        }
+
+        context("parsing a null value with a serializer that uses YAML location information when throwing exceptions") {
+            test("throws an exception with the correct location information") {
+                val exception = shouldThrow<LocationInformationException> { Yaml.default.decodeFromString(LocationThrowingSerializer, input) }
+
+                exception.asClue {
+                    it.message shouldBe "Serializer called with location (1, 1) and path: <root>"
+                }
+            }
+        }
+    }
+})