feat(assert): added jsonPathEquals

src/main/java/me/itzg/helpers/assertcmd/AssertCommand.java

@@ -4,7 +4,8 @@
 
 @Command(name = "assert", description = "Provides assertion operators for verifying container setup",
   subcommands = {
-    FileExists.class
+      FileExists.class,
+      JsonPathEquals.class,
   }
 )
 public class AssertCommand {

src/main/java/me/itzg/helpers/assertcmd/JsonPathEquals.java

@@ -0,0 +1,50 @@
+package me.itzg.helpers.assertcmd;
+
+import com.jayway.jsonpath.DocumentContext;
+import com.jayway.jsonpath.JsonPath;
+import com.jayway.jsonpath.PathNotFoundException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Objects;
+import java.util.concurrent.Callable;
+import picocli.CommandLine.Command;
+import picocli.CommandLine.ExitCode;
+import picocli.CommandLine.Option;
+
+@Command(name = "jsonPathEquals")
+public class JsonPathEquals implements Callable<Integer> {
+  @Option(names = "--file", required = true)
+  Path file;
+
+  @Option(names = "--path", required = true)
+  String jsonPath;
+
+  @Option(names = "--expect", required = true)
+  String expectedValue;
+
+  @Override
+  public Integer call() throws Exception {
+    if (!Files.exists(file)) {
+      System.err.printf("The file %s does not exist%n", file);
+      return ExitCode.SOFTWARE;
+    }
+
+    final DocumentContext doc = JsonPath.parse(file.toFile());
+
+    final String result;
+    try {
+      result = doc.read(jsonPath, String.class);
+    } catch (PathNotFoundException e) {
+      System.err.printf("The path %s in %s does not exist%n",
+          jsonPath, file);
+      return ExitCode.SOFTWARE;
+    }
+    if (!Objects.equals(result, expectedValue)) {
+      System.err.printf("Expected '%s' at the path %s in %s, but was '%s'%n",
+          expectedValue, jsonPath, file, result);
+      return ExitCode.SOFTWARE;
+    }
+
+    return ExitCode.OK;
+  }
+}

src/test/java/me/itzg/helpers/assertcmd/JsonPathEqualsTest.java

@@ -0,0 +1,139 @@
+package me.itzg.helpers.assertcmd;
+
+import static com.github.stefanbirkner.systemlambda.SystemLambda.tapSystemErrNormalized;
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Collections;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+import picocli.CommandLine;
+
+class JsonPathEqualsTest {
+
+  @Test
+  void passesForString(@TempDir Path tempDir) throws IOException {
+    final Path opsJson = Files.write(tempDir.resolve("ops.json"),
+        Collections.singletonList(
+            "[ { \"uuid\": \"1-2-3-4\", \"name\": \"itzg\", \"level\": 4 } ]"
+        )
+    );
+
+    final int exitCode = new CommandLine(new JsonPathEquals())
+        .execute(
+            "--file=" + opsJson,
+            "--path=$[0].name",
+            "--expect=itzg"
+        );
+
+    assertThat(exitCode).isEqualTo(0);
+  }
+
+  @Test
+  void passesForNumber(@TempDir Path tempDir) throws IOException {
+    final Path opsJson = Files.write(tempDir.resolve("ops.json"),
+        Collections.singletonList(
+            "[ { \"uuid\": \"1-2-3-4\", \"name\": \"itzg\", \"level\": 4 } ]"
+        )
+    );
+
+    final int exitCode = new CommandLine(new JsonPathEquals())
+        .execute(
+            "--file=" + opsJson,
+            "--path=$[0].level",
+            "--expect=4"
+        );
+
+    assertThat(exitCode).isEqualTo(0);
+  }
+
+  @Test
+  void failsForMismatch(@TempDir Path tempDir) throws Exception {
+    final Path opsJson = Files.write(tempDir.resolve("ops.json"),
+        Collections.singletonList(
+            "[ { \"uuid\": null, \"name\": \"itzg\", \"level\": 4 } ]"
+        )
+    );
+
+    final String errOut = tapSystemErrNormalized(() -> {
+      final int exitCode = new CommandLine(new JsonPathEquals())
+          .execute(
+              "--file=" + opsJson,
+              "--path=$[0].name",
+              "--expect=notg"
+          );
+
+      assertThat(exitCode).isEqualTo(1);
+    });
+
+    assertThat(errOut).isEqualTo("Expected 'notg' at the path $[0].name in " + opsJson
+        + ", but was 'itzg'\n");
+  }
+
+  @Test
+  void failsForMissingField(@TempDir Path tempDir) throws Exception {
+    final Path opsJson = Files.write(tempDir.resolve("ops.json"),
+        Collections.singletonList(
+            "[ { \"uuid\": null, \"name\": \"itzg\", \"level\": 4 } ]"
+        )
+    );
+
+    final String errOut = tapSystemErrNormalized(() -> {
+      final int exitCode = new CommandLine(new JsonPathEquals())
+          .execute(
+              "--file=" + opsJson,
+              "--path=$[0].doesNotExist",
+              "--expect=NA"
+          );
+
+      assertThat(exitCode).isEqualTo(1);
+    });
+
+    assertThat(errOut).isEqualTo("The path $[0].doesNotExist in " + opsJson
+        + " does not exist\n");
+  }
+
+  @Test
+  void failsForNullField(@TempDir Path tempDir) throws Exception {
+    final Path opsJson = Files.write(tempDir.resolve("ops.json"),
+        Collections.singletonList(
+            "[ { \"uuid\": null, \"name\": \"itzg\", \"level\": 4 } ]"
+        )
+    );
+
+    final String errOut = tapSystemErrNormalized(() -> {
+      final int exitCode = new CommandLine(new JsonPathEquals())
+          .execute(
+              "--file=" + opsJson,
+              "--path=$[0].uuid",
+              "--expect=1-2-3-4"
+          );
+
+      assertThat(exitCode).isEqualTo(1);
+    });
+
+    assertThat(errOut).isEqualTo("Expected '1-2-3-4' at the path $[0].uuid in " + opsJson
+        + ", but was 'null'\n");
+  }
+
+  @Test
+  void failsForMissingFile(@TempDir Path tempDir) throws Exception {
+    final Path missingPath = tempDir.resolve("ops.json");
+
+    final String errOut = tapSystemErrNormalized(() -> {
+
+      final int exitCode = new CommandLine(new JsonPathEquals())
+          .execute(
+              "--file=" + missingPath,
+              "--path=$[0].uuid",
+              "--expect=1-2-3-4"
+          );
+
+      assertThat(exitCode).isEqualTo(1);
+    });
+
+    assertThat(errOut).isEqualTo("The file " + missingPath + " does not exist\n");
+  }
+}