Add FineractClientTest for Fineract SDK REST Client (FINERACT-1216)

and introduce handy Calls utilitiy

fineract-client/build.gradle

@@ -87,3 +87,7 @@ configurations {
     generatedCompile.extendsFrom implementation
     generatedRuntime.extendsFrom runtime
 }
+
+test {
+    useJUnitPlatform()
+}

fineract-client/dependencies.gradle

@@ -39,6 +39,13 @@ dependencies {
             'commons-codec:commons-codec',
             )
     implementation('org.apache.oltu.oauth2:org.apache.oltu.oauth2.client') {
-        exclude group: 'org.apache.oltu.oauth2' , module: 'org.apache.oltu.oauth2.common'
+        exclude group: 'org.apache.oltu.oauth2', module: 'org.apache.oltu.oauth2.common'
     }
+    testImplementation(
+            'org.junit.jupiter:junit-jupiter-api:5.7.0',
+            'com.google.truth:truth:1.0.1'
+            )
+    testRuntimeOnly(
+            'org.junit.jupiter:junit-jupiter-engine:5.7.0'
+            )
 }

fineract-client/src/main/java/org/apache/fineract/client/util/Calls.java

@@ -0,0 +1,51 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you 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
+ *
+ * http://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.apache.fineract.client.util;
+
+import java.io.IOException;
+import retrofit2.Call;
+import retrofit2.Response;
+
+/**
+ * Extension methods for {@link Call}. This class is recommended to be statically imported.
+ *
+ * @author Michael Vorburger.ch
+ */
+public class Calls {
+
+    private Calls() {}
+
+    /**
+     * Execute a Call, expecting success.
+     *
+     * @param call
+     *            the Call to execute
+     * @return the body of the successful call (never null)
+     * @throws IOException
+     *             thrown either if a problem occurred talking to the server, or the HTTP response code was not
+     *             [200..300) successful
+     */
+    public static <T> T ok(Call<T> call) throws IOException {
+        Response<T> response = call.execute();
+        if (response.isSuccessful()) {
+            return response.body();
+        }
+        throw new IOException("HTTP failed: " + call.request() + "; " + response);
+    }
+}

fineract-client/src/main/java/org/apache/fineract/client/util/FineractClient.java

@@ -0,0 +1,86 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you 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
+ *
+ * http://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.apache.fineract.client.util;
+
+import org.apache.fineract.client.ApiClient;
+import org.apache.fineract.client.auth.ApiKeyAuth;
+
+/**
+ * Fineract Client Java SDK API entry point. This is recommended to be used instead of {@link ApiClient}.
+ *
+ * @author Michael Vorburger.ch
+ */
+public class FineractClient {
+
+    private final ApiClient apiClient;
+
+    private FineractClient(ApiClient apiClient) {
+        this.apiClient = apiClient;
+    }
+
+    public static FineractClientBuilder builder() {
+        return new FineractClientBuilder();
+    }
+
+    public <S> S createService(Class<S> serviceClass) {
+        return apiClient.createService(serviceClass);
+    }
+
+    public static class FineractClientBuilder {
+
+        private String baseURL;
+        private String tenant;
+        private String username;
+        private String password;
+
+        private FineractClientBuilder() {}
+
+        public FineractClientBuilder baseURL(String baseURL) {
+            this.baseURL = baseURL;
+            return this;
+        }
+
+        public FineractClientBuilder tenant(String tenant) {
+            this.tenant = tenant;
+            return this;
+        }
+
+        public FineractClientBuilder basicAuth(String username, String password) {
+            this.username = username;
+            this.password = password;
+            return this;
+        }
+
+        public FineractClient build() {
+            ApiClient apiClient = new ApiClient("basicAuth", has("username", username), has("password", password));
+            apiClient.getAdapterBuilder().baseUrl(has("baseURL", baseURL));
+            ApiKeyAuth authorization = new ApiKeyAuth("header", "fineract-platform-tenantid");
+            authorization.setApiKey(has("tenant", tenant));
+            apiClient.addAuthorization("tenantid", authorization);
+            return new FineractClient(apiClient);
+        }
+
+        private <T> T has(String propertyName, T value) throws IllegalStateException {
+            if (value == null) {
+                throw new IllegalStateException("Must call " + propertyName + "(...) to create valid Builder");
+            }
+            return value;
+        }
+    }
+}

fineract-client/src/test/java/org/apache/fineract/client/test/FineractClientTest.java

@@ -0,0 +1,58 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you 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
+ *
+ * http://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.apache.fineract.client.test;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.apache.fineract.client.util.Calls.ok;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.io.IOException;
+import org.apache.fineract.client.services.ClientApi;
+import org.apache.fineract.client.util.FineractClient;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Illustrates use of Fineract SDK REST Client.
+ *
+ * @author Michael Vorburger.ch
+ */
+public class FineractClientTest {
+
+    @Test
+    void testRetrieveAllClients() throws IOException {
+        FineractClient client = FineractClient.builder().baseURL("https://demo.fineract.dev/fineract-provider/api/v1/").tenant("default")
+                .basicAuth("mifos", "password").build();
+        ClientApi clientApi = client.createService(ClientApi.class);
+        assertThat(ok(clientApi.retrieveAll20(null, null, null, null, null, null, null, null, 0, 100, null, null, null))
+                .getTotalFilteredRecords()).isAtLeast(3);
+    }
+
+    @Test
+    void testFineractClientBuilder() throws IOException {
+        assertThrows(IllegalStateException.class, () -> {
+            FineractClient.builder().build();
+        });
+        assertThrows(IllegalStateException.class, () -> {
+            FineractClient.builder().baseURL("https://server/").build();
+        });
+        assertThrows(IllegalStateException.class, () -> {
+            FineractClient.builder().baseURL("https://server/").tenant("default").build();
+        });
+    }
+}