Test status quo for ConditionEvaluationResult and its factory methods

Prior to this commit, we did not have any "unit tests" for
ConditionEvaluationResult, and while working on #4698 I noticed that we
in fact have several issues in the implementation of and documentation
for ConditionEvaluationResult.

Thus, this commit introduces dedicated unit tests for the status quo,
where individual TODOs will be addressed in separate issues/commits.

See #4698
See #4699 (comment)

(cherry picked from commit 3026c62)

Author: sbrannen

jupiter-tests/src/test/java/org/junit/jupiter/api/condition/ConditionEvaluationResultTests.java

@@ -0,0 +1,164 @@
+/*
+ * Copyright 2015-2025 the original author or authors.
+ *
+ * All rights reserved. This program and the accompanying materials are
+ * made available under the terms of the Eclipse Public License v2.0 which
+ * accompanies this distribution and is available at
+ *
+ * https://www.eclipse.org/legal/epl-v20.html
+ */
+
+package org.junit.jupiter.api.condition;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ConditionEvaluationResult;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.NullSource;
+import org.junit.jupiter.params.provider.ValueSource;
+
+/**
+ * Unit tests for {@link ConditionEvaluationResult}.
+ *
+ * @since 5.13.3
+ */
+class ConditionEvaluationResultTests {
+
+	@Test
+	void enabledWithReason() {
+		var result = ConditionEvaluationResult.enabled("reason");
+
+		assertThat(result.isDisabled()).isFalse();
+		assertThat(result.getReason()).contains("reason");
+		assertThat(result).asString()//
+				.isEqualTo("ConditionEvaluationResult [enabled = true, reason = 'reason']");
+	}
+
+	@EmptyReasonsTest
+	void enabledWithInvalidReason(String reason) {
+		@SuppressWarnings("NullAway")
+		var result = ConditionEvaluationResult.enabled(reason);
+
+		assertThat(result.isDisabled()).isFalse();
+
+		if (reason == null) {
+			assertThat(result.getReason()).isEmpty();
+			assertThat(result).asString()//
+					.isEqualTo("ConditionEvaluationResult [enabled = true, reason = '<unknown>']");
+		}
+		// TODO Remove else-block once issues are addressed.
+		else {
+			assertThat(result.getReason()).contains(reason);
+			assertThat(result).asString()//
+					.isEqualTo("ConditionEvaluationResult [enabled = true, reason = '%s']", reason);
+		}
+	}
+
+	@Test
+	void disabledWithDefaultReason() {
+		var result = ConditionEvaluationResult.disabled("default");
+
+		assertThat(result.isDisabled()).isTrue();
+		assertThat(result.getReason()).contains("default");
+		assertThat(result).asString()//
+				.isEqualTo("ConditionEvaluationResult [enabled = false, reason = 'default']");
+	}
+
+	@EmptyReasonsTest
+	void disabledWithInvalidDefaultReason(String reason) {
+		@SuppressWarnings("NullAway")
+		var result = ConditionEvaluationResult.disabled(reason);
+
+		assertThat(result.isDisabled()).isTrue();
+
+		if (reason == null) {
+			assertThat(result.getReason()).isEmpty();
+			assertThat(result).asString()//
+					.isEqualTo("ConditionEvaluationResult [enabled = false, reason = '<unknown>']");
+		}
+		// TODO Remove else-block once issues are addressed.
+		else {
+			assertThat(result.getReason()).contains(reason);
+			assertThat(result).asString()//
+					.isEqualTo("ConditionEvaluationResult [enabled = false, reason = '%s']", reason);
+		}
+	}
+
+	@EmptyReasonsTest
+	void disabledWithValidDefaultReasonAndInvalidCustomReason(String customReason) {
+		@SuppressWarnings("NullAway")
+		var result = ConditionEvaluationResult.disabled("default", customReason);
+
+		assertThat(result.isDisabled()).isTrue();
+		assertThat(result.getReason()).contains("default");
+		assertThat(result).asString()//
+				.isEqualTo("ConditionEvaluationResult [enabled = false, reason = 'default']");
+	}
+
+	@EmptyReasonsTest
+	void disabledWithInvalidDefaultReasonAndValidCustomReason(String reason) {
+		@SuppressWarnings("NullAway")
+		var result = ConditionEvaluationResult.disabled(reason, "custom");
+
+		assertThat(result.isDisabled()).isTrue();
+
+		// TODO Convert to single assertion once issues are addressed.
+		// The following should hold for all null/blank default reasons.
+		// assertThat(result).asString().isEqualTo("ConditionEvaluationResult [enabled = false, reason = 'custom']");
+
+		if (reason == null) {
+			assertThat(result.getReason()).contains("null ==> custom");
+			assertThat(result).asString()//
+					.isEqualTo("ConditionEvaluationResult [enabled = false, reason = 'null ==> custom']");
+		}
+		else {
+			var generatedReason = reason + " ==> custom";
+			assertThat(result.getReason()).contains(generatedReason);
+			assertThat(result).asString()//
+					.isEqualTo("ConditionEvaluationResult [enabled = false, reason = '%s']", generatedReason);
+		}
+	}
+
+	@EmptyReasonsTest
+	void disabledWithInvalidDefaultReasonAndInvalidCustomReason(String reason) {
+		// We intentionally use the reason as both the default and custom reason.
+		@SuppressWarnings("NullAway")
+		var result = ConditionEvaluationResult.disabled(reason, reason);
+
+		assertThat(result.isDisabled()).isTrue();
+
+		if (reason == null) {
+			assertThat(result.getReason()).isEmpty();
+			assertThat(result).asString()//
+					.isEqualTo("ConditionEvaluationResult [enabled = false, reason = '<unknown>']");
+		}
+		// TODO Remove else-block once issues are addressed.
+		else {
+			assertThat(result.getReason()).contains(reason);
+			assertThat(result).asString()//
+					.isEqualTo("ConditionEvaluationResult [enabled = false, reason = '%s']", reason);
+		}
+	}
+
+	@Test
+	void disabledWithValidDefaultReasonAndCustomReason() {
+		var result = ConditionEvaluationResult.disabled("default", "custom");
+
+		assertThat(result.isDisabled()).isTrue();
+		assertThat(result.getReason()).contains("default ==> custom");
+		assertThat(result).asString()//
+				.isEqualTo("ConditionEvaluationResult [enabled = false, reason = 'default ==> custom']");
+	}
+
+	@Retention(RetentionPolicy.RUNTIME)
+	@ParameterizedTest
+	@NullSource
+	@ValueSource(strings = { "", " ", "   ", "\t", "\n" })
+	@interface EmptyReasonsTest {
+	}
+
+}