Fixture templating: adds the ability to create fixtures from templates files using dynamic values

README.md

@@ -118,10 +118,10 @@ To add a fixture all you have to do is call one of the `addFixture` methods in t
 serverRule.addFixture(200, "body.json");
 ```
 
-This will add a response with status code 200 and the contents of the file `body.json` as the body. This file, by default, must be located in a folder with name `fixtures`. This folder works different for Local Tests and Instrumented Tests.
+This will add a response with status code 200 and the contents of the file `body.json` as the body. This file, by default, must be located in a folder with name `fixtures`. This folder works differently for Local Tests and Instrumented Tests.
 
 - Local tests: these are run locally in the JVM (usually with Robolectric) and follow different conventions. Your source folder `test` may contain a folder `java` and a folder `resources`. When you compile your code it takes everything in the `resources` folder and puts in the root of your `.class` files. So, your fixtures folder must go inside `resources` folder.
-- Instrumented tests: there are run in a device or emulator (usually with Espresso or Robotium). It follows the android folder layout and so you may have an assets folder inside your `androidTest` folder. Your `fixtures` folder must go there.
+- Instrumented tests: these are run on a device or emulator (usually with Espresso or Robotium). It follows the android folder layout and so you may have an assets folder inside your `androidTest` folder. Your `fixtures` folder must go there.
 
 Because of these differences, there are two implementations of `RequestMatcherRule`: `LocalTestRequestMatcherRule` and `InstrumentedTestRequestMatcherRule`. You should use the generic type for your variable and instantiate it with the required type. Example:
 
@@ -141,6 +141,33 @@ The difference is that when we run an InstrumentedTest, we must pass the instrum
 
 More on the difference between each kind of test [here](https://medium.com/concrete-solutions/android-local-or-instrumented-tests-9da545af7777#.mmowgemc4)
 
+#### Fixture templating
+
+You can also provide templates for cases when you need dynamic values to be passed to the JSON. For
+this to work you need to provide a JSON file with keys that will be replaced by their values in runtime.
+
+A valid JSON template is:
+
+``` json 
+{
+  "current_date": "${current_date}"
+}
+```
+
+And it can be used like this:
+
+``` java
+
+String timestamp = String.valueOf(new Date(778338900L).getTime());
+
+server.addTemplate("json_template.json")
+      .withValueForKey("current_date", timestamp)
+      .ifRequestMatches("/get_current_date");
+
+// interact with server and make response assertions
+
+```
+
 ## Configuring the `RequestMatcherRule`
 
 It is possible to pass some parameters to the server rule's constructor:

requestmatcher/src/androidTest/assets/fixtures/json_error_template.json

@@ -0,0 +1,3 @@
+{
+  "error_message": "${error}"
+}

requestmatcher/src/androidTest/assets/fixtures/json_template.json

@@ -0,0 +1,3 @@
+{
+  "current_date": "${current_date}"
+}

requestmatcher/src/main/java/br/com/concretesolutions/requestmatcher/RequestMatcherRule.java

@@ -126,7 +126,7 @@ public MockWebServer getMockWebServer() {
     public String readFixture(final String fixturePath) {
         try {
             return IOReader.read(open(fixturesRootFolder + "/" + fixturePath)) + "\n";
-        } catch (IOException e) {
+        } catch (IOException | IllegalArgumentException e) {
             throw new RuntimeException("Failed to read asset with path " + fixturePath, e);
         }
     }
@@ -187,25 +187,32 @@ public IfRequestMatches<RequestMatchersGroup> addFixture(String fixturePath) {
      */
     public IfRequestMatches<RequestMatchersGroup> addFixture(int statusCode, String fixturePath) {
 
-        final MockResponse mockResponse = new MockResponse()
-                .setResponseCode(statusCode)
-                .setBody(readFixture(fixturePath));
-
-        if (guessMimeType) {
-            final String mimeType = IOReader.mimeTypeFromExtension(fixturePath);
+        String body = readFixture(fixturePath);
+        return addResponse(prepareMockResponse(statusCode, fixturePath, body));
+    }
 
-            if (mimeType != null) {
-                mockResponse.addHeader("Content-Type", mimeType);
-            }
-        }
+    /**
+     * Adds a template to be used during the test case, later turning it into a fixture to be used.
+     *
+     * @param templatePath The path of the fixture inside the fixtures folder.
+     * @return A dsl instance {@link DynamicIfRequestMatches} for chaining
+     */
+    public DynamicIfRequestMatches<RequestMatchersGroup> addTemplate(String templatePath) {
+        return addTemplate(200, templatePath);
+    }
 
-        if (!defaultHeaders.isEmpty()) {
-            for (String headerKey : defaultHeaders.keySet()) {
-                mockResponse.addHeader(headerKey, defaultHeaders.get(headerKey));
-            }
-        }
+    /**
+     * Adds a template to be used during the test case, later turning it into a fixture to be used.
+     *
+     * @param templatePath The path of the fixture inside the fixtures folder.
+     * @param statusCode   The status of the mocked response.
+     * @return A dsl instance {@link DynamicIfRequestMatches} for chaining
+     */
+    public DynamicIfRequestMatches<RequestMatchersGroup> addTemplate(int statusCode, String templatePath) {
 
-        return addResponse(mockResponse);
+        String templateBody = readFixture(templatePath);
+        return new DynamicIfRequestMatches<>(new RequestMatchersGroup(), dispatcher,
+                templateBody, prepareMockResponse(statusCode, templatePath, ""));
     }
 
     /**
@@ -258,6 +265,54 @@ public T ifRequestMatches() {
         }
     }
 
+    public static class DynamicIfRequestMatches<T extends RequestMatchersGroup> extends IfRequestMatches<T> {
+
+        private final HashMap<String, String> values = new HashMap<>();
+        private final String templateBody;
+        private final MockResponse response;
+        private final MatcherDispatcher dispatcher;
+
+        private DynamicIfRequestMatches(T group, MatcherDispatcher dispatcher,
+                                        String templateBody, MockResponse mockResponse) {
+            super(group);
+            this.templateBody = templateBody;
+            this.dispatcher = dispatcher;
+            this.response = mockResponse;
+        }
+
+        @Override
+        public T ifRequestMatches() {
+            return dispatchDynamic(super.ifRequestMatches(), values);
+        }
+
+        public DynamicIfRequestMatches<T> withValueForKey(String key, String value) {
+            values.put(key, value);
+            return this;
+        }
+
+        private T dispatchDynamic(T group, HashMap<String, String> values) {
+            response.setBody(replaceValues(values));
+            dispatcher.addFixture(response, group);
+            return group;
+        }
+
+        private String replaceValues(HashMap<String, String> values) {
+            String body = templateBody;
+
+            for (String key : values.keySet()) {
+                String keyFinder = "${" + key + "}";
+
+                if (!body.contains(keyFinder))
+                    fail("Could not find any template key named " + key);
+
+                body = body.replace(keyFinder, values.get(key));
+            }
+
+            return body;
+        }
+
+    }
+
     private void after(Exception exception, boolean success) throws Exception {
 
         if (dispatcher.getAssertionException() != null) {
@@ -324,4 +379,27 @@ public void evaluate() throws Throwable {
             }
         };
     }
+
+    private MockResponse prepareMockResponse(int statusCode, String path, String body) {
+
+        final MockResponse mockResponse = new MockResponse()
+                .setResponseCode(statusCode)
+                .setBody(body);
+
+        if (guessMimeType) {
+            final String mimeType = IOReader.mimeTypeFromExtension(path);
+
+            if (mimeType != null) {
+                mockResponse.addHeader("Content-Type", mimeType);
+            }
+        }
+
+        if (!defaultHeaders.isEmpty()) {
+            for (String headerKey : defaultHeaders.keySet()) {
+                mockResponse.addHeader(headerKey, defaultHeaders.get(headerKey));
+            }
+        }
+
+        return mockResponse;
+    }
 }

requestmatcher/src/test-common/java/br/com/concretesolutions/requestmatcher/test/RequestMatcherRuleTest.java

@@ -8,6 +8,7 @@
 import org.junit.rules.TestRule;
 
 import java.io.IOException;
+import java.util.Date;
 import java.util.concurrent.TimeUnit;
 
 import br.com.concretesolutions.requestmatcher.RequestMatcherRule;
@@ -799,4 +800,66 @@ public void informsAboutNotUsedFixture() throws IOException {
 
         client.newCall(request0).execute(); // will fail with message of non used matchers
     }
+
+    @Test
+    public void canReplaceValuesInTemplate() throws IOException {
+
+        String timestamp = String.valueOf(new Date(1519775413753L).getTime());
+
+        server.addTemplate("json_template.json")
+                .withValueForKey("current_date", timestamp)
+                .ifRequestMatches();
+
+        this.request = new Request.Builder()
+                .url(server.url("/get"))
+                .get()
+                .build();
+
+        final Response resp = client.newCall(request).execute();
+
+        assertThat(resp.isSuccessful(), is(true));
+        assertThat(resp.headers().get("Content-Type"), is("application/json"));
+        assertThat(resp.peekBody(1_000_000).source().readUtf8(),
+                containsString("\"current_date\": \"1519775413753\""));
+    }
+
+    @Test
+    public void canReplaceValuesInTemplateWithNonSuccessfulResponse() throws IOException {
+
+        server.addTemplate(404, "json_error_template.json")
+                .withValueForKey("error", "Resource not found")
+                .ifRequestMatches();
+
+        this.request = new Request.Builder()
+                .url(server.url("/get"))
+                .get()
+                .build();
+
+        final Response resp = client.newCall(request).execute();
+
+        assertThat(resp.code() == 404, is(true));
+        assertThat(resp.headers().get("Content-Type"), is("application/json"));
+        assertThat(resp.peekBody(1_000_000).source().readUtf8(),
+                containsString("\"error_message\": \"Resource not found\""));
+    }
+
+    @Test
+    public void failsIfTemplateDoesNotHaveGivenKeys() throws IOException {
+
+        exceptionRule.expect(AssertionError.class);
+        exceptionRule.expectMessage(containsString("Could not find any template key named something"));
+
+        server.addTemplate("body.json")
+                .withValueForKey("something", "something")
+                .ifRequestMatches();
+
+        this.request = new Request.Builder()
+                .url(server.url("/get"))
+                .get()
+                .build();
+
+        client.newCall(request).execute();
+    }
+
+
 }

requestmatcher/src/test/resources/fixtures/json_error_template.json

@@ -0,0 +1,3 @@
+{
+  "error_message": "${error}"
+}

requestmatcher/src/test/resources/fixtures/json_template.json

@@ -0,0 +1,3 @@
+{
+  "current_date": "${current_date}"
+}