FormatDiffCli improvements (#41)

<!-- User-facing outcomes this PR delivers -->

Author: iamdanfox

build.gradle

@@ -48,4 +48,14 @@ subprojects {
     tasks.withType(Checkstyle) {
         enabled = false
     }
+
+    tasks.withType(JavaCompile) {
+        options.errorprone.errorproneArgs += [
+            '-Xep:PreconditionsConstantMessage:OFF',
+            '-Xep:PreferSafeLoggableExceptions:OFF',
+            '-Xep:PreferAssertj:OFF',
+            '-Xep:PreferSafeLoggingPreconditions:OFF',
+            '-Xep:SwitchStatementDefaultCase:OFF'
+        ]
+    }
 }

palantir-java-format/build.gradle

@@ -13,6 +13,7 @@ dependencies {
     testCompile 'com.google.guava:guava-testlib'
     testCompile 'com.google.truth:truth'
     testCompile 'com.google.testing.compile:compile-testing'
+    testImplementation 'org.assertj:assertj-core'
     testImplementation 'org.junit.jupiter:junit-jupiter-migrationsupport'
     testImplementation 'org.junit.jupiter:junit-jupiter'
 

palantir-java-format/src/main/java/com/palantir/javaformat/java/FormatDiffCli.java renamed to palantir-java-format/src/main/java/com/palantir/javaformat/java/FormatDiff.java

@@ -37,7 +37,7 @@
 import java.util.regex.Pattern;
 import java.util.stream.Stream;
 
-public final class FormatDiffCli {
+public final class FormatDiff {
     // each section in the git diff output starts like this
     private static final Pattern SEPARATOR = Pattern.compile("diff --git");
 
@@ -48,15 +48,16 @@ public final class FormatDiffCli {
     private static final Pattern HUNK =
             Pattern.compile("^@@.*\\+(?<startLineOneIndexed>\\d+)(,(?<numLines>\\d+))?", Pattern.MULTILINE);
 
-    public static void main(String[] _args) throws IOException, InterruptedException {
+    public static void formatDiff(Path dirToFormat) throws IOException, InterruptedException {
         Formatter formatter = Formatter.createFormatter(
                 JavaFormatterOptions.builder().style(JavaFormatterOptions.Style.PALANTIR).build());
-        Path cwd = Paths.get(".");
 
-        String gitOutput = gitDiff(cwd);
+        String gitOutput = gitDiff(dirToFormat);
+        Path gitTopLevelDir = gitTopLevelDir(dirToFormat);
+
         parseGitDiffOutput(gitOutput)
                 .filter(diff -> diff.path.toString().endsWith(".java"))
-                .map(diff -> new SingleFileDiff(cwd.resolve(diff.path), diff.lineRanges))
+                .map(diff -> new SingleFileDiff(gitTopLevelDir.resolve(diff.path), diff.lineRanges))
                 .filter(diff -> Files.exists(diff.path))
                 .forEach(diff -> format(formatter, diff));
     }
@@ -107,14 +108,24 @@ private static void format(Formatter formatter, SingleFileDiff diff) {
         }
     }
 
-    private static String gitDiff(Path cwd) throws IOException, InterruptedException {
+    private static String gitDiff(Path dir) throws IOException, InterruptedException {
         // TODO(dfox): this does nothing if working dir is clean - maybe use HEAD^ to format prev commit?
-        Process process = new ProcessBuilder().command("git", "diff", "-U0", "HEAD").directory(cwd.toFile()).start();
+        return gitCommand(dir, "git", "diff", "-U0", "HEAD", dir.toAbsolutePath().toString());
+    }
+
+    private static Path gitTopLevelDir(Path dir) throws IOException, InterruptedException {
+        return Paths.get(gitCommand(dir, "git", "rev-parse", "--show-toplevel"));
+    }
+
+    private static String gitCommand(Path dir, String... args) throws IOException, InterruptedException {
+        Process process = new ProcessBuilder().command(args).directory(dir.toFile()).start();
+
         Preconditions.checkState(process.waitFor(10, TimeUnit.SECONDS), "git diff took too long to terminate");
+        Preconditions.checkState(process.exitValue() == 0, "Expected return code of 0");
 
         ByteArrayOutputStream baos = new ByteArrayOutputStream();
         ByteStreams.copy(process.getInputStream(), baos);
-        return new String(baos.toByteArray(), UTF_8);
+        return new String(baos.toByteArray(), UTF_8).trim();
     }
 
     // TODO(dfox): replace this with immutables

palantir-java-format/src/test/java/com/palantir/javaformat/java/FormatDiffCliTest.java

@@ -0,0 +1,93 @@
+/*
+ * (c) Copyright 2019 Palantir Technologies Inc. All rights reserved.
+ *
+ * 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
+ *
+ *     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 com.palantir.javaformat.java;
+
+import static java.nio.charset.StandardCharsets.UTF_8;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+import com.google.common.io.ByteStreams;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.Collectors;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+class FormatDiffTest {
+    @TempDir Path repo;
+
+    @Test
+    void parsing_git_diff_output_works() throws IOException {
+        String example1 = new String(
+                Files.readAllBytes(
+                        Paths.get("src/test/resources/com/palantir/javaformat/java/FormatDiffCliTest/example1.patch")),
+                StandardCharsets.UTF_8);
+
+        List<String> strings = FormatDiff.parseGitDiffOutput(example1).map(FormatDiff.SingleFileDiff::toString).collect(
+                Collectors.toList());
+        assertEquals(
+                ImmutableList.of(
+                        "SingleFileDiff{path=build.gradle, lineRanges=[[24..25), [29..30)]}",
+                        "SingleFileDiff{path=tracing/src/test/java/com/palantir/tracing/TracersTest.java, "
+                                + "lineRanges=[[659..660), [675..676)]}"),
+                strings);
+    }
+
+    @Test
+    void reformat_a_subpath_of_a_git_directory_for_only_changed_lines() throws IOException, InterruptedException {
+        runCommandInRepo("git", "init");
+        runCommandInRepo("git", "config", "user.name", "Test User");
+        runCommandInRepo("git", "config", "user.email", "[email protected]");
+        runCommandInRepo("git", "commit", "--allow-empty", "-m", "Init");
+
+        Path subdir = repo.resolve("subdir");
+        Files.createDirectories(subdir);
+
+        Path reformatMe = subdir.resolve("ReformatMe.java");
+        Files.write(reformatMe, ImmutableList.of("                                 class ReformatMe {}"), UTF_8);
+
+        Path dontTouchMe = repo.resolve("DontTouchMe.java");
+        Files.write(dontTouchMe, ImmutableList.of("                                 class DontTouchMe {}"), UTF_8);
+
+        runCommandInRepo("git", "add", "-N", ".");
+
+        FormatDiff.formatDiff(subdir);
+
+        assertThat(reformatMe).hasContent("class ReformatMe {}");
+        assertThat(dontTouchMe).hasContent("                                 class DontTouchMe {}");
+    }
+
+    private void runCommandInRepo(String... args) throws IOException, InterruptedException {
+        Process process = new ProcessBuilder().command(args).directory(repo.toFile()).start();
+
+        Preconditions.checkState(process.waitFor(10, TimeUnit.SECONDS), "git diff took too long to terminate");
+
+        ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        ByteStreams.copy(process.getErrorStream(), baos);
+        String stderr = new String(baos.toByteArray(), UTF_8);
+
+        Preconditions.checkState(process.exitValue() == 0, "Expected return code of 0: " + stderr);
+    }
+}

palantir-java-format/src/test/java/com/palantir/javaformat/java/FormatDiffTest.java

@@ -29,6 +29,7 @@ com.netflix.nebula:nebula-test:7.4.0 (1 constraints: 0d051a36)
 commons-io:commons-io:2.5 (1 constraints: eb0c8d0a)
 junit:junit:4.12 (6 constraints: f14f0a8f)
 org.apiguardian:apiguardian-api:1.1.0 (6 constraints: 18697c5a)
+org.assertj:assertj-core:3.13.2 (1 constraints: 3b05403b)
 org.checkerframework:checker-compat-qual:2.5.5 (1 constraints: 640a29b9)
 org.hamcrest:hamcrest-core:1.3 (1 constraints: cc05fe3f)
 org.junit.jupiter:junit-jupiter:5.5.2 (1 constraints: 0e051536)

versions.lock

@@ -1,16 +1,17 @@
-gradle.plugin.org.jetbrains.gradle.plugin.idea-ext:gradle-idea-ext = 0.5
 com.github.ben-manes.caffeine:caffeine = 2.8.0
-com.google.guava:guava = 27.0.1-jre
-com.google.errorprone:javac-shaded = 9+181-r4173-1
+com.google.auto.service:auto-service = 1.0-rc6
 com.google.code.findbugs:jsr305 = 3.0.2
 com.google.errorprone:error_prone_annotations = 2.3.3
-junit:junit = 4.12
+com.google.errorprone:javac-shaded = 9+181-r4173-1
+com.google.guava:guava = 27.0.1-jre
 com.google.guava:guava-testlib = 27.0.1-jre
-com.google.truth:truth = 1.0
 com.google.testing.compile:compile-testing = 0.15
+com.google.truth:truth = 1.0
+com.netflix.nebula:nebula-test = 7.4.0
+gradle.plugin.org.jetbrains.gradle.plugin.idea-ext:gradle-idea-ext = 0.5
+junit:junit = 4.12
+org.assertj:assertj-core = 3.13.2
 org.derive4j:* = 1.1.1
 org.immutables:value = 2.8.1
 org.junit.jupiter:* = 5.5.2
 org.junit.vintage:* = 5.5.0
-com.google.auto.service:auto-service = 1.0-rc6
-com.netflix.nebula:nebula-test = 7.4.0