Add FailureAnalyzer for InvalidSchemaLocationsException

This commit adds a new `FailureAnalyzer` for exceptions thrown when no
GraphQL schema file could be found.
This lists configured locations (with `"classpath:..."` notation) and
also resolved locations - this helps developers figure out how the
pattern are resolved and why schema files cannot be found.

See gh-29140

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/graphql/InvalidSchemaLocationsExceptionFailureAnalyzerTests.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright 2012-2021 the original author or authors.
+ *
+ * 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 org.springframework.boot.autoconfigure.graphql;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.diagnostics.FailureAnalysis;
+import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
+import org.springframework.core.io.support.ResourcePatternResolver;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link InvalidSchemaLocationsExceptionFailureAnalyzer}
+ *
+ * @author Brian Clozel
+ */
+class InvalidSchemaLocationsExceptionFailureAnalyzerTests {
+
+	private final InvalidSchemaLocationsExceptionFailureAnalyzer analyzer = new InvalidSchemaLocationsExceptionFailureAnalyzer();
+
+	private final ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
+
+	private final String[] missingLocation = new String[] {
+			"classpath:org/springframework/boot/autoconfigure/graphql/missing/" };
+
+	private final String[] existingLocation = new String[] {
+			"classpath:org/springframework/boot/autoconfigure/graphql/" };
+
+	@Test
+	void shouldReportCause() {
+		InvalidSchemaLocationsException exception = new InvalidSchemaLocationsException(this.existingLocation,
+				this.resolver);
+		FailureAnalysis analysis = this.analyzer.analyze(exception);
+		assertThat(analysis.getCause()).isInstanceOf(InvalidSchemaLocationsException.class);
+		assertThat(analysis.getAction()).contains("Check that the following locations contain schema files:");
+	}
+
+	@Test
+	void shouldListUnresolvableLocation() {
+		InvalidSchemaLocationsException exception = new InvalidSchemaLocationsException(this.missingLocation,
+				this.resolver);
+		FailureAnalysis analysis = this.analyzer.analyze(exception);
+		assertThat(analysis.getAction()).contains(this.existingLocation[0]).doesNotContain("file:");
+	}
+
+	@Test
+	void shouldListExistingLocation() {
+		InvalidSchemaLocationsException exception = new InvalidSchemaLocationsException(this.existingLocation,
+				this.resolver);
+		FailureAnalysis analysis = this.analyzer.analyze(exception);
+		assertThat(analysis.getAction()).contains(this.existingLocation[0]).contains("file:");
+	}
+
+}