test: Add comprehensive Document class validation and functionality tests

Co-authored-by: Oleksandr Klymenko <[email protected]>
Signed-off-by: Oleksandr Klymenko <[email protected]>

Auto-cherry-pick to 1.0.x
Fixes #4174

Author: alxkm

spring-ai-commons/src/test/java/org/springframework/ai/document/ContentFormatterTests.java

@@ -16,11 +16,16 @@
 
 package org.springframework.ai.document;
 
+import java.util.HashMap;
 import java.util.Map;
 
 import org.junit.jupiter.api.Test;
+import org.springframework.ai.document.id.IdGenerator;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.AssertionsForClassTypes.assertThatThrownBy;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
 
 /**
  * @author Christian Tzolov
@@ -62,4 +67,196 @@ void defaultConfigTextFormatter() {
 			.isEqualTo(defaultConfigFormatter.format(this.document, MetadataMode.ALL));
 	}
 
+	@Test
+	void shouldThrowWhenIdIsNull() {
+		assertThatThrownBy(() -> new Document(null, "text", new HashMap<>()))
+			.isInstanceOf(IllegalArgumentException.class)
+			.hasMessageContaining("id cannot be null or empty");
+	}
+
+	@Test
+	void shouldThrowWhenIdIsEmpty() {
+		assertThatThrownBy(() -> new Document("", "text", new HashMap<>())).isInstanceOf(IllegalArgumentException.class)
+			.hasMessageContaining("id cannot be null or empty");
+	}
+
+	@Test
+	void shouldThrowWhenMetadataIsNull() {
+		assertThatThrownBy(() -> new Document("Sample text", null)).isInstanceOf(IllegalArgumentException.class)
+			.hasMessageContaining("metadata cannot be null");
+	}
+
+	@Test
+	void shouldThrowWhenMetadataHasNullKey() {
+		Map<String, Object> metadata = new HashMap<>();
+		metadata.put(null, "value");
+
+		assertThatThrownBy(() -> new Document("Sample text", metadata)).isInstanceOf(IllegalArgumentException.class)
+			.hasMessageContaining("metadata cannot have null keys");
+	}
+
+	@Test
+	void shouldThrowWhenMetadataHasNullValue() {
+		Map<String, Object> metadata = new HashMap<>();
+		metadata.put("key", null);
+
+		assertThatThrownBy(() -> new Document("Sample text", metadata)).isInstanceOf(IllegalArgumentException.class)
+			.hasMessageContaining("metadata cannot have null values");
+	}
+
+	@Test
+	void shouldThrowWhenNeitherTextNorMediaAreSet() {
+		assertThatThrownBy(() -> Document.builder().id("test-id").metadata("key", "value").build())
+			.isInstanceOf(IllegalArgumentException.class)
+			.hasMessageContaining("exactly one of text or media must be specified");
+	}
+
+	@Test
+	void builderWithCustomIdGenerator() {
+		IdGenerator mockGenerator = mock(IdGenerator.class);
+		when(mockGenerator.generateId("test text", Map.of("key", "value"))).thenReturn("generated-id");
+
+		Document document = Document.builder()
+			.idGenerator(mockGenerator)
+			.text("test text")
+			.metadata("key", "value")
+			.build();
+
+		assertThat(document.getId()).isEqualTo("generated-id");
+	}
+
+	@Test
+	void builderShouldThrowWhenIdGeneratorIsNull() {
+		assertThatThrownBy(() -> Document.builder().idGenerator(null)).isInstanceOf(IllegalArgumentException.class)
+			.hasMessageContaining("idGenerator cannot be null");
+	}
+
+	@Test
+	void builderShouldThrowWhenMetadataKeyIsNull() {
+		assertThatThrownBy(() -> Document.builder().metadata(null, "value"))
+			.isInstanceOf(IllegalArgumentException.class)
+			.hasMessageContaining("metadata key cannot be null");
+	}
+
+	@Test
+	void builderShouldThrowWhenMetadataValueIsNull() {
+		assertThatThrownBy(() -> Document.builder().metadata("key", null)).isInstanceOf(IllegalArgumentException.class)
+			.hasMessageContaining("metadata value cannot be null");
+	}
+
+	@Test
+	void setCustomContentFormatter() {
+		Document document = new Document("Sample text", Map.of());
+		ContentFormatter customFormatter = mock(ContentFormatter.class);
+		when(customFormatter.format(document, MetadataMode.ALL)).thenReturn("Custom formatted content");
+
+		document.setContentFormatter(customFormatter);
+
+		assertThat(document.getContentFormatter()).isEqualTo(customFormatter);
+		assertThat(document.getFormattedContent()).isEqualTo("Custom formatted content");
+	}
+
+	@Test
+	void shouldThrowWhenFormatterIsNull() {
+		Document document = new Document("Sample text", Map.of());
+
+		assertThatThrownBy(() -> document.getFormattedContent(null, MetadataMode.ALL))
+			.isInstanceOf(IllegalArgumentException.class)
+			.hasMessageContaining("formatter must not be null");
+	}
+
+	@Test
+	void shouldThrowWhenMetadataModeIsNull() {
+		Document document = new Document("Sample text", Map.of());
+
+		assertThatThrownBy(() -> document.getFormattedContent(null)).isInstanceOf(IllegalArgumentException.class)
+			.hasMessageContaining("Metadata mode must not be null");
+	}
+
+	@Test
+	void mutateTextDocument() {
+		Document original = new Document("id", "original text", Map.of("key", "value"));
+
+		Document mutated = original.mutate().text("modified text").metadata("newKey", "newValue").score(0.9).build();
+
+		assertThat(mutated.getId()).isEqualTo("id");
+		assertThat(mutated.getText()).isEqualTo("modified text");
+		assertThat(mutated.getMetadata()).containsEntry("newKey", "newValue");
+		assertThat(mutated.getScore()).isEqualTo(0.9);
+
+		// Original should be unchanged
+		assertThat(original.getText()).isEqualTo("original text");
+		assertThat(original.getScore()).isNull();
+	}
+
+	@Test
+	void equalDocuments() {
+		Map<String, Object> metadata = Map.of("key", "value");
+		Document doc1 = new Document("id", "text", metadata);
+		Document doc2 = new Document("id", "text", metadata);
+
+		assertThat(doc1).isEqualTo(doc2);
+		assertThat(doc1.hashCode()).isEqualTo(doc2.hashCode());
+	}
+
+	@Test
+	void differentIds() {
+		Map<String, Object> metadata = Map.of("key", "value");
+		Document doc1 = new Document("id1", "text", metadata);
+		Document doc2 = new Document("id2", "text", metadata);
+
+		assertThat(doc1).isNotEqualTo(doc2);
+	}
+
+	@Test
+	void differentText() {
+		Map<String, Object> metadata = Map.of("key", "value");
+		Document doc1 = new Document("id", "text1", metadata);
+		Document doc2 = new Document("id", "text2", metadata);
+
+		assertThat(doc1).isNotEqualTo(doc2);
+	}
+
+	@Test
+	void isTextReturnsTrueForTextDocument() {
+		Document document = new Document("Sample text", Map.of());
+		assertThat(document.isText()).isTrue();
+		assertThat(document.getText()).isNotNull();
+		assertThat(document.getMedia()).isNull();
+	}
+
+	@Test
+	void scoreHandling() {
+		Document document = Document.builder().text("test").score(0.85).build();
+
+		assertThat(document.getScore()).isEqualTo(0.85);
+
+		Document documentWithoutScore = new Document("test");
+		assertThat(documentWithoutScore.getScore()).isNull();
+	}
+
+	@Test
+	void metadataImmutability() {
+		Map<String, Object> originalMetadata = new HashMap<>();
+		originalMetadata.put("key", "value");
+
+		Document document = new Document("test", originalMetadata);
+
+		// Modify original map
+		originalMetadata.put("newKey", "newValue");
+
+		// Document's metadata should not be affected
+		assertThat(document.getMetadata()).hasSize(1);
+		assertThat(document.getMetadata()).containsEntry("key", "value");
+		assertThat(document.getMetadata()).doesNotContainKey("newKey");
+	}
+
+	@Test
+	void builderWithMetadataMap() {
+		Map<String, Object> metadata = Map.of("key1", "value1", "key2", 1);
+		Document document = Document.builder().text("test").metadata(metadata).build();
+
+		assertThat(document.getMetadata()).containsExactlyInAnyOrderEntriesOf(metadata);
+	}
+
 }