Move the MakeVariableExpander to a new package

Rename it to TemplateExpander and start rewriting the documentation to refer
to template variables.

PiperOrigin-RevId: 171648255

1 files changed, 149 insertions, 0 deletions

diff --git a/src/test/java/com/google/devtools/build/lib/analysis/stringtemplate/TemplateExpanderTest.java b/src/test/java/com/google/devtools/build/lib/analysis/stringtemplate/TemplateExpanderTest.java
new file mode 100644
index 0000000000..fa61f091b3
--- /dev/null
+++ b/src/test/java/com/google/devtools/build/lib/analysis/stringtemplate/TemplateExpanderTest.java
@@ -0,0 +1,149 @@
+// Copyright 2006 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.analysis.stringtemplate;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.fail;
+
+import java.util.HashMap;
+import java.util.Map;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/**
+ * Unit tests for the {@link
+ * com.google.devtools.build.lib.analysis.stringtemplate.TemplateExpander}, which expands variable
+ * references of the form <code>"$x"</code> and <code>"$(foo)"</code> into their corresponding
+ * values.
+ */
+@RunWith(JUnit4.class)
+public class TemplateExpanderTest {
+
+  private TemplateContext context;
+
+  private Map<String, String> vars = new HashMap<>();
+
+  @Before
+  public final void createContext() throws Exception  {
+    context = new TemplateContext() {
+        @Override
+        public String lookupVariable(String name)
+            throws ExpansionException {
+          // Not a Make variable. Let the shell handle the expansion.
+          if (name.startsWith("$")) {
+            return name;
+          }
+          if (!vars.containsKey(name)) {
+            throw new ExpansionException(String.format("$(%s) not defined", name));
+          }
+          return vars.get(name);
+        }
+      };
+
+    vars.put("SRCS", "src1 src2");
+  }
+
+  private void assertExpansionEquals(String expected, String cmd)
+      throws ExpansionException {
+    assertThat(TemplateExpander.expand(cmd, context)).isEqualTo(expected);
+  }
+
+  private void assertExpansionFails(String expectedErrorSuffix, String cmd) {
+    try {
+      TemplateExpander.expand(cmd, context);
+      fail("Expansion of " + cmd + " didn't fail as expected");
+    } catch (Exception e) {
+      assertThat(e).hasMessageThat().isEqualTo(expectedErrorSuffix);
+    }
+  }
+
+  @Test
+  public void testExpansion() throws Exception {
+    vars.put("<", "src1");
+    vars.put("OUTS", "out1 out2");
+    vars.put("@", "out1");
+    vars.put("^", "src1 src2 dep1 dep2");
+    vars.put("@D", "outdir");
+    vars.put("BINDIR", "bindir");
+
+    assertExpansionEquals("src1 src2", "$(SRCS)");
+    assertExpansionEquals("src1", "$<");
+    assertExpansionEquals("out1 out2", "$(OUTS)");
+    assertExpansionEquals("out1", "$(@)");
+    assertExpansionEquals("out1", "$@");
+    assertExpansionEquals("out1,", "$@,");
+
+    assertExpansionEquals("src1 src2 out1 out2", "$(SRCS) $(OUTS)");
+
+    assertExpansionEquals("cmd", "cmd");
+    assertExpansionEquals("cmd src1 src2,", "cmd $(SRCS),");
+    assertExpansionEquals("label1 src1 src2,", "label1 $(SRCS),");
+    assertExpansionEquals(":label1 src1 src2,", ":label1 $(SRCS),");
+
+    // Note: $(location x) is considered an undefined variable;
+    assertExpansionFails("$(location label1) not defined",
+                         "$(location label1), $(SRCS),");
+  }
+
+  @Test
+  public void testRecursiveExpansion() throws Exception {
+    // Expansion is recursive: $(recursive) -> $(SRCS) -> "src1 src2"
+    vars.put("recursive", "$(SRCS)");
+    assertExpansionEquals("src1 src2", "$(recursive)");
+
+    // Recursion does not span expansion boundaries:
+    // $(recur2a)$(recur2b) --> "$" + "(SRCS)"  --/--> "src1 src2"
+    vars.put("recur2a", "$$");
+    vars.put("recur2b", "(SRCS)");
+    assertExpansionEquals("$(SRCS)", "$(recur2a)$(recur2b)");
+  }
+
+  @Test
+  public void testInfiniteRecursionFailsGracefully() throws Exception {
+    vars.put("infinite", "$(infinite)");
+    assertExpansionFails("potentially unbounded recursion during expansion "
+                         + "of '$(infinite)'",
+                         "$(infinite)");
+
+    vars.put("black", "$(white)");
+    vars.put("white", "$(black)");
+    assertExpansionFails("potentially unbounded recursion during expansion "
+                         + "of '$(black)'",
+                         "$(white) is the new $(black)");
+  }
+
+  @Test
+  public void testErrors() throws Exception {
+    assertExpansionFails("unterminated variable reference", "$(SRCS");
+    assertExpansionFails("unterminated $", "$");
+
+    String suffix = "instead for \"Make\" variables, or escape the '$' as '$$' if you intended "
+        + "this for the shell";
+    assertExpansionFails("'$file' syntax is not supported; use '$(file)' " + suffix,
+                         "for file in a b c;do echo $file;done");
+    assertExpansionFails("'${file%:.*8}' syntax is not supported; use '$(file%:.*8)' " + suffix,
+                         "${file%:.*8}");
+  }
+
+  @Test
+  public void testShellVariables() throws Exception {
+    assertExpansionEquals("for file in a b c;do echo $file;done",
+        "for file in a b c;do echo $$file;done");
+    assertExpansionEquals("${file%:.*8}", "$${file%:.*8}");
+    assertExpansionFails("$(basename file) not defined", "$(basename file)");
+    assertExpansionEquals("$(basename file)", "$$(basename file)");
+  }
+}