Add a new file path type, LocalPath.

This path type is a local file path as a wrapper around a string. It works much the same as java.io.File, but without its file operations.

For the most part, FilePath shouldn't add much overhead compared to using plain strings. Strings do get normalised on the way in, but no extra objects are allocated unless the path actually needs normalisation.

PiperOrigin-RevId: 178798497

4 files changed, 561 insertions, 0 deletions

diff --git a/src/test/java/com/google/devtools/build/lib/vfs/LocalPathAbstractTest.java b/src/test/java/com/google/devtools/build/lib/vfs/LocalPathAbstractTest.java
new file mode 100644
index 0000000000..93869521ad
--- /dev/null
+++ b/src/test/java/com/google/devtools/build/lib/vfs/LocalPathAbstractTest.java
@@ -0,0 +1,180 @@
+// Copyright 2017 The Bazel Authors. 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.google.devtools.build.lib.vfs;
+
+import static com.google.common.truth.Truth.assertThat;
+import static com.google.devtools.build.lib.testutil.MoreAsserts.assertThrows;
+import static java.util.stream.Collectors.toList;
+
+import com.google.common.collect.Lists;
+import com.google.common.testing.EqualsTester;
+import com.google.devtools.build.lib.vfs.LocalPath.OsPathPolicy;
+import java.util.Collections;
+import java.util.List;
+import org.junit.Before;
+import org.junit.Test;
+
+/** Tests for {@link LocalPath}. */
+public abstract class LocalPathAbstractTest {
+
+  private OsPathPolicy os;
+
+  @Before
+  public void setup() {
+    os = getFilePathOs();
+  }
+
+  @Test
+  public void testEqualsAndHashCode() {
+    new EqualsTester()
+        .addEqualityGroup(
+            create("../relative/path"), create("..").getRelative("relative").getRelative("path"))
+        .addEqualityGroup(create("something/else"))
+        .addEqualityGroup(create(""), LocalPath.EMPTY)
+        .testEquals();
+  }
+
+  @Test
+  public void testRelativeTo() {
+    assertThat(create("").relativeTo(create("")).getPathString()).isEmpty();
+    assertThat(create("foo").relativeTo(create("foo")).getPathString()).isEmpty();
+    assertThat(create("foo/bar/baz").relativeTo(create("foo")).getPathString())
+        .isEqualTo("bar/baz");
+    assertThat(create("foo/bar/baz").relativeTo(create("foo/bar")).getPathString())
+        .isEqualTo("baz");
+    assertThat(create("foo").relativeTo(create("")).getPathString()).isEqualTo("foo");
+
+    // Cannot relativize non-ancestors
+    assertThrows(IllegalArgumentException.class, () -> create("foo/bar").relativeTo(create("fo")));
+
+    // Make sure partial directory matches aren't reported
+    assertThrows(
+        IllegalArgumentException.class, () -> create("foo/bar").relativeTo(create("foo/ba")));
+  }
+
+  @Test
+  public void testGetRelative() {
+    assertThat(create("a").getRelative("b").getPathString()).isEqualTo("a/b");
+    assertThat(create("a/b").getRelative("c/d").getPathString()).isEqualTo("a/b/c/d");
+    assertThat(create("a").getRelative("").getPathString()).isEqualTo("a");
+    assertThat(create("a/b").getRelative("../c").getPathString()).isEqualTo("a/c");
+    assertThat(create("a/b").getRelative("..").getPathString()).isEqualTo("a");
+  }
+
+  @Test
+  public void testEmptyPathToEmptyPath() {
+    // compare string forms
+    assertThat(create("").getPathString()).isEmpty();
+    // compare fragment forms
+    assertThat(create("")).isEqualTo(create(""));
+  }
+
+  @Test
+  public void testSimpleNameToSimpleName() {
+    // compare string forms
+    assertThat(create("foo").getPathString()).isEqualTo("foo");
+    // compare fragment forms
+    assertThat(create("foo")).isEqualTo(create("foo"));
+  }
+
+  @Test
+  public void testSimplePathToSimplePath() {
+    // compare string forms
+    assertThat(create("foo/bar").getPathString()).isEqualTo("foo/bar");
+    // compare fragment forms
+    assertThat(create("foo/bar")).isEqualTo(create("foo/bar"));
+  }
+
+  @Test
+  public void testStripsTrailingSlash() {
+    // compare string forms
+    assertThat(create("foo/bar/").getPathString()).isEqualTo("foo/bar");
+    // compare fragment forms
+    assertThat(create("foo/bar/")).isEqualTo(create("foo/bar"));
+  }
+
+  @Test
+  public void testGetParentDirectory() {
+    LocalPath fooBarWiz = create("foo/bar/wiz");
+    LocalPath fooBar = create("foo/bar");
+    LocalPath foo = create("foo");
+    LocalPath empty = create("");
+    assertThat(fooBarWiz.getParentDirectory()).isEqualTo(fooBar);
+    assertThat(fooBar.getParentDirectory()).isEqualTo(foo);
+    assertThat(foo.getParentDirectory()).isEqualTo(empty);
+    assertThat(empty.getParentDirectory()).isNull();
+  }
+
+  @Test
+  public void testBasename() throws Exception {
+    assertThat(create("foo/bar").getBaseName()).isEqualTo("bar");
+    assertThat(create("foo/").getBaseName()).isEqualTo("foo");
+    assertThat(create("foo").getBaseName()).isEqualTo("foo");
+    assertThat(create("").getBaseName()).isEmpty();
+  }
+
+  @Test
+  public void testStartsWith() {
+    // (relative path, relative prefix) => true
+    assertThat(create("foo/bar").startsWith(create("foo/bar"))).isTrue();
+    assertThat(create("foo/bar").startsWith(create("foo"))).isTrue();
+    assertThat(create("foot/bar").startsWith(create("foo"))).isFalse();
+  }
+
+  @Test
+  public void testNormalize() {
+    assertThat(create("a/b")).isEqualTo(create("a/b"));
+    assertThat(create("a/../../b")).isEqualTo(create("../b"));
+    assertThat(create("a/../..")).isEqualTo(create(".."));
+    assertThat(create("a/../b")).isEqualTo(create("b"));
+    assertThat(create("a/b/../b")).isEqualTo(create("a/b"));
+  }
+
+  @Test
+  public void testNormalStringsDoNotAllocate() {
+    String normal1 = "a/b/hello.txt";
+    assertThat(create(normal1).getPathString()).isSameAs(normal1);
+
+    // Sanity check our testing strategy
+    String notNormal = "a/../b";
+    assertThat(create(notNormal).getPathString()).isNotSameAs(notNormal);
+  }
+
+  @Test
+  public void testComparableSortOrder() {
+    List<LocalPath> list =
+        Lists.newArrayList(
+            create("zzz"),
+            create("ZZZ"),
+            create("ABC"),
+            create("aBc"),
+            create("AbC"),
+            create("abc"));
+    Collections.sort(list);
+    List<String> result = list.stream().map(LocalPath::getPathString).collect(toList());
+
+    if (os.isCaseSensitive()) {
+      assertThat(result).containsExactly("ABC", "AbC", "ZZZ", "aBc", "abc", "zzz").inOrder();
+    } else {
+      // Partial ordering among case-insensitive items guaranteed by Collections.sort stability
+      assertThat(result).containsExactly("ABC", "aBc", "AbC", "abc", "zzz", "ZZZ").inOrder();
+    }
+  }
+
+  protected abstract OsPathPolicy getFilePathOs();
+
+  protected LocalPath create(String path) {
+    return LocalPath.createWithOs(path, os);
+  }
+}
diff --git a/src/test/java/com/google/devtools/build/lib/vfs/MacOsLocalPathTest.java b/src/test/java/com/google/devtools/build/lib/vfs/MacOsLocalPathTest.java
new file mode 100644
index 0000000000..c99ad487ee
--- /dev/null
+++ b/src/test/java/com/google/devtools/build/lib/vfs/MacOsLocalPathTest.java
@@ -0,0 +1,48 @@
+// Copyright 2017 The Bazel Authors. 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.google.devtools.build.lib.vfs;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.testing.EqualsTester;
+import com.google.devtools.build.lib.vfs.LocalPath.MacOsPathPolicy;
+import com.google.devtools.build.lib.vfs.LocalPath.OsPathPolicy;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Tests Mac-specific parts of {@link LocalPath}. */
+@RunWith(JUnit4.class)
+public class MacOsLocalPathTest extends UnixLocalPathTest {
+
+  @Override
+  protected OsPathPolicy getFilePathOs() {
+    return new MacOsPathPolicy();
+  }
+
+  @Test
+  public void testMacEqualsAndHashCode() {
+    new EqualsTester()
+        .addEqualityGroup(create("a/b"), create("A/B"))
+        .addEqualityGroup(create("/a/b"), create("/A/B"))
+        .addEqualityGroup(create("something/else"))
+        .addEqualityGroup(create("/something/else"))
+        .testEquals();
+  }
+
+  @Test
+  public void testCaseIsPreserved() {
+    assertThat(create("a/B").getPathString()).isEqualTo("a/B");
+  }
+}
diff --git a/src/test/java/com/google/devtools/build/lib/vfs/UnixLocalPathTest.java b/src/test/java/com/google/devtools/build/lib/vfs/UnixLocalPathTest.java
new file mode 100644
index 0000000000..2cdb4014ae
--- /dev/null
+++ b/src/test/java/com/google/devtools/build/lib/vfs/UnixLocalPathTest.java
@@ -0,0 +1,169 @@
+// Copyright 2017 The Bazel Authors. 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.google.devtools.build.lib.vfs;
+
+import static com.google.common.truth.Truth.assertThat;
+import static com.google.devtools.build.lib.testutil.MoreAsserts.assertThrows;
+
+import com.google.common.testing.EqualsTester;
+import com.google.devtools.build.lib.vfs.LocalPath.OsPathPolicy;
+import com.google.devtools.build.lib.vfs.LocalPath.UnixOsPathPolicy;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Tests the unix implementation of {@link LocalPath}. */
+@RunWith(JUnit4.class)
+public class UnixLocalPathTest extends LocalPathAbstractTest {
+
+  @Test
+  public void testEqualsAndHashCodeUnix() {
+    new EqualsTester()
+        .addEqualityGroup(create("/something/else"))
+        .addEqualityGroup(create("/"), create("//////"))
+        .testEquals();
+  }
+
+  @Test
+  public void testRelativeToUnix() {
+    // Cannot relativize absolute and non-absolute
+    assertThat(create("c/d").getRelative("/a/b").getPathString()).isEqualTo("/a/b");
+    assertThat(create("/").relativeTo(create("/")).getPathString()).isEmpty();
+    assertThat(create("/foo").relativeTo(create("/foo")).getPathString()).isEmpty();
+    assertThat(create("/foo/bar/baz").relativeTo(create("/foo")).getPathString())
+        .isEqualTo("bar/baz");
+    assertThat(create("/foo/bar/baz").relativeTo(create("/foo/bar")).getPathString())
+        .isEqualTo("baz");
+    assertThat(create("/foo").relativeTo(create("/")).getPathString()).isEqualTo("foo");
+    assertThrows(
+        IllegalArgumentException.class, () -> create("/foo/bar/baz").relativeTo(create("foo")));
+    assertThrows(
+        IllegalArgumentException.class, () -> create("/foo").relativeTo(create("/foo/bar/baz")));
+  }
+
+  @Test
+  public void testIsAbsoluteUnix() {
+    assertThat(create("/absolute/test").isAbsolute()).isTrue();
+    assertThat(create("relative/test").isAbsolute()).isFalse();
+  }
+
+  @Test
+  public void testGetRelativeUnix() {
+    assertThat(create("/a").getRelative("b").getPathString()).isEqualTo("/a/b");
+    assertThat(create("/").getRelative("").getPathString()).isEqualTo("/");
+    assertThat(create("c/d").getRelative("/a/b").getPathString()).isEqualTo("/a/b");
+  }
+
+  @Test
+  public void testEmptyPathToEmptyPathUnix() {
+    // compare string forms
+    assertThat(create("/").getPathString()).isEqualTo("/");
+    // compare fragment forms
+    assertThat(create("/")).isEqualTo(create("/"));
+  }
+
+  @Test
+  public void testRedundantSlashes() {
+    // compare string forms
+    assertThat(create("///").getPathString()).isEqualTo("/");
+    // compare fragment forms
+    assertThat(create("///")).isEqualTo(create("/"));
+    // compare string forms
+    assertThat(create("/foo///bar").getPathString()).isEqualTo("/foo/bar");
+    // compare fragment forms
+    assertThat(create("/foo///bar")).isEqualTo(create("/foo/bar"));
+    // compare string forms
+    assertThat(create("////foo//bar").getPathString()).isEqualTo("/foo/bar");
+    // compare fragment forms
+    assertThat(create("////foo//bar")).isEqualTo(create("/foo/bar"));
+  }
+
+  @Test
+  public void testSimpleNameToSimpleNameUnix() {
+    // compare string forms
+    assertThat(create("/foo").getPathString()).isEqualTo("/foo");
+    // compare fragment forms
+    assertThat(create("/foo")).isEqualTo(create("/foo"));
+  }
+
+  @Test
+  public void testSimplePathToSimplePathUnix() {
+    // compare string forms
+    assertThat(create("/foo/bar").getPathString()).isEqualTo("/foo/bar");
+    // compare fragment forms
+    assertThat(create("/foo/bar")).isEqualTo(create("/foo/bar"));
+  }
+
+  @Test
+  public void testGetParentDirectoryUnix() {
+    LocalPath fooBarWizAbs = create("/foo/bar/wiz");
+    LocalPath fooBarAbs = create("/foo/bar");
+    LocalPath fooAbs = create("/foo");
+    LocalPath rootAbs = create("/");
+    assertThat(fooBarWizAbs.getParentDirectory()).isEqualTo(fooBarAbs);
+    assertThat(fooBarAbs.getParentDirectory()).isEqualTo(fooAbs);
+    assertThat(fooAbs.getParentDirectory()).isEqualTo(rootAbs);
+    assertThat(rootAbs.getParentDirectory()).isNull();
+  }
+
+  @Test
+  public void testBasenameUnix() throws Exception {
+    assertThat(create("/foo/bar").getBaseName()).isEqualTo("bar");
+    assertThat(create("/foo/").getBaseName()).isEqualTo("foo");
+    assertThat(create("/foo").getBaseName()).isEqualTo("foo");
+    assertThat(create("/").getBaseName()).isEmpty();
+  }
+
+  @Test
+  public void testStartsWithUnix() {
+    LocalPath foobar = create("/foo/bar");
+    LocalPath foobarRelative = create("foo/bar");
+
+    // (path, prefix) => true
+    assertThat(foobar.startsWith(foobar)).isTrue();
+    assertThat(foobar.startsWith(create("/"))).isTrue();
+    assertThat(foobar.startsWith(create("/foo"))).isTrue();
+    assertThat(foobar.startsWith(create("/foo/"))).isTrue();
+    assertThat(foobar.startsWith(create("/foo/bar/"))).isTrue(); // Includes trailing slash.
+
+    // (prefix, path) => false
+    assertThat(create("/foo").startsWith(foobar)).isFalse();
+    assertThat(create("/").startsWith(foobar)).isFalse();
+
+    // (absolute, relative) => false
+    assertThat(foobar.startsWith(foobarRelative)).isFalse();
+    assertThat(foobarRelative.startsWith(foobar)).isFalse();
+
+    // relative paths start with nothing, absolute paths do not
+    assertThat(foobar.startsWith(create(""))).isFalse();
+
+    // (path, sibling) => false
+    assertThat(create("/foo/wiz").startsWith(foobar)).isFalse();
+    assertThat(foobar.startsWith(create("/foo/wiz"))).isFalse();
+  }
+
+  @Test
+  public void testNormalizeUnix() {
+    assertThat(create("/a/b")).isEqualTo(create("/a/b"));
+    assertThat(create("/a/b/")).isEqualTo(create("/a/b"));
+    assertThat(create("/a/./b")).isEqualTo(create("/a/b"));
+    assertThat(create("/a/../b")).isEqualTo(create("/b"));
+    assertThat(create("/..")).isEqualTo(create("/.."));
+  }
+
+  @Override
+  protected OsPathPolicy getFilePathOs() {
+    return new UnixOsPathPolicy();
+  }
+}
diff --git a/src/test/java/com/google/devtools/build/lib/vfs/WindowsLocalPathTest.java b/src/test/java/com/google/devtools/build/lib/vfs/WindowsLocalPathTest.java
new file mode 100644
index 0000000000..ac5acef1f4
--- /dev/null
+++ b/src/test/java/com/google/devtools/build/lib/vfs/WindowsLocalPathTest.java
@@ -0,0 +1,164 @@
+// Copyright 2017 The Bazel Authors. 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.google.devtools.build.lib.vfs;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.testing.EqualsTester;
+import com.google.devtools.build.lib.testutil.MoreAsserts;
+import com.google.devtools.build.lib.vfs.LocalPath.OsPathPolicy;
+import com.google.devtools.build.lib.vfs.LocalPath.WindowsOsPathPolicy;
+import com.google.devtools.build.lib.vfs.LocalPath.WindowsOsPathPolicy.ShortPathResolver;
+import java.util.HashMap;
+import java.util.Map;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Tests windows-specific parts of {@link LocalPath} */
+@RunWith(JUnit4.class)
+public class WindowsLocalPathTest extends LocalPathAbstractTest {
+
+  private static final class MockShortPathResolver implements ShortPathResolver {
+    // Full path to resolved child mapping.
+    private Map<String, String> resolutions = new HashMap<>();
+
+    @Override
+    public String resolveShortPath(String path) {
+      String[] segments = path.split("[\\\\/]+");
+      String result = "";
+      for (int i = 0; i < segments.length; ) {
+        String segment = segments[i];
+        String queryString = (result + segment).toLowerCase();
+        segment = resolutions.getOrDefault(queryString, segment);
+        result = result + segment;
+        ++i;
+        if (i != segments.length) {
+          result += "/";
+        }
+      }
+      return result;
+    }
+  }
+
+  private final MockShortPathResolver shortPathResolver = new MockShortPathResolver();
+
+  @Override
+  protected OsPathPolicy getFilePathOs() {
+    return new WindowsOsPathPolicy(shortPathResolver);
+  }
+
+  @Test
+  public void testEqualsAndHashcodeWindows() {
+    new EqualsTester()
+        .addEqualityGroup(create("a/b"), create("A/B"))
+        .addEqualityGroup(create("/a/b"), create("/A/B"))
+        .addEqualityGroup(create("c:/a/b"), create("C:\\A\\B"))
+        .addEqualityGroup(create("something/else"))
+        .testEquals();
+  }
+
+  @Test
+  public void testCaseIsPreserved() {
+    assertThat(create("a/B").getPathString()).isEqualTo("a/B");
+  }
+
+  @Test
+  public void testNormalizeWindows() {
+    assertThat(create("C:/")).isEqualTo(create("C:/"));
+    assertThat(create("c:/")).isEqualTo(create("C:/"));
+    assertThat(create("c:\\")).isEqualTo(create("C:/"));
+    assertThat(create("c:\\foo\\..\\bar\\")).isEqualTo(create("C:/bar"));
+  }
+
+  @Test
+  public void testStartsWithWindows() {
+    assertThat(create("C:/").startsWith(create("C:/"))).isTrue();
+    assertThat(create("C:/foo").startsWith(create("C:/"))).isTrue();
+    assertThat(create("C:/foo").startsWith(create("D:/"))).isFalse();
+
+    // Case insensitivity test
+    assertThat(create("C:/foo/bar").startsWith(create("C:/FOO"))).isTrue();
+  }
+
+  @Test
+  public void testGetParentDirectoryWindows() {
+    assertThat(create("C:/foo").getParentDirectory()).isEqualTo(create("C:/"));
+    assertThat(create("C:/").getParentDirectory()).isNull();
+  }
+
+  @Test
+  public void testisAbsoluteWindows() {
+    assertThat(create("C:/").isAbsolute()).isTrue();
+    // test that msys paths turn into absolute paths
+    assertThat(create("/").isAbsolute()).isTrue();
+  }
+
+  @Test
+  public void testRelativeToWindows() {
+    assertThat(create("C:/foo").relativeTo(create("C:/"))).isEqualTo(create("foo"));
+    // Case insensitivity test
+    assertThat(create("C:/foo/bar").relativeTo(create("C:/FOO"))).isEqualTo(create("bar"));
+    MoreAsserts.assertThrows(
+        IllegalArgumentException.class, () -> create("D:/foo").relativeTo(create("C:/")));
+  }
+
+  @Test
+  public void testAbsoluteUnixPathIsRelativeToWindowsUnixRoot() {
+    assertThat(create("/").getPathString()).isEqualTo("C:/fake/msys");
+    assertThat(create("/foo/bar").getPathString()).isEqualTo("C:/fake/msys/foo/bar");
+    assertThat(create("/foo/bar").getPathString()).isEqualTo("C:/fake/msys/foo/bar");
+  }
+
+  @Test
+  public void testAbsoluteUnixPathReferringToDriveIsRecognized() {
+    assertThat(create("/c/foo").getPathString()).isEqualTo("C:/foo");
+    assertThat(create("/c/foo").getPathString()).isEqualTo("C:/foo");
+    assertThat(create("/c:").getPathString()).isNotEqualTo("C:/foo");
+  }
+
+  @Test
+  public void testResolvesShortenedPaths() {
+    shortPathResolver.resolutions.put("d:/progra~1", "program files");
+    shortPathResolver.resolutions.put("d:/program files/micros~1", "microsoft something");
+    shortPathResolver.resolutions.put(
+        "d:/program files/microsoft something/foo/~bar~1", "~bar_hello");
+
+    // Assert normal shortpath resolution.
+    LocalPath normal = create("d:/progra~1/micros~1/foo/~bar~1/baz");
+    // The path string has an upper-case drive letter because that's how path printing works.
+    assertThat(normal.getPathString())
+        .isEqualTo("D:/program files/microsoft something/foo/~bar_hello/baz");
+    LocalPath notYetExistent = create("d:/progra~1/micros~1/foo/will~1.exi/bar");
+    // The path string has an upper-case drive letter because that's how path printing works.
+    assertThat(notYetExistent.getPathString())
+        .isEqualTo("D:/program files/microsoft something/foo/will~1.exi/bar");
+
+    LocalPath msRoot = create("d:/progra~1/micros~1");
+    assertThat(msRoot.getPathString()).isEqualTo("D:/program files/microsoft something");
+
+    // Pretend that a path we already failed to resolve once came into existence.
+    shortPathResolver.resolutions.put(
+        "d:/program files/microsoft something/foo/will~1.exi", "will.exist");
+
+    // Assert that this time we can resolve the previously non-existent path.
+    LocalPath nowExists = create("d:/progra~1/micros~1/foo/will~1.exi/bar");
+    // The path string has an upper-case drive letter because that's how path printing works.
+    assertThat(nowExists.getPathString())
+        .isEqualTo("D:/program files/microsoft something/foo/will.exist/bar");
+
+    // Assert relative paths that look like short paths are untouched
+    assertThat(create("progra~1").getPathString()).isEqualTo("progra~1");
+  }
+}