Bug 1436151 - Breakpoints at the beginning of a line are missed. r=jimb

--HG--
extra : rebase_source : 247b33c30e746b81edc78a8e3bdcb99ae97f598e

devtools/server/actors/source.js

@@ -907,7 +907,15 @@ let SourceActor = ActorClassWithSpec(sourceSpec, {
           entryPoints.push({ script, offsets });
         }
       }
-    } else {
+
+      if (entryPoints.length > 0) {
+        setBreakpointAtEntryPoints(actor, entryPoints);
+        return true;
+      }
+
+      return false;
+    }
+
     // This is a column breakpoint, so we are interested in all column
     // offsets that correspond to the given line *and* column number.
     for (let script of scripts) {
@@ -921,11 +929,26 @@ let SourceActor = ActorClassWithSpec(sourceSpec, {
         }
       }
     }
+
+    // If we don't find any matching entrypoints, then
+    // we should check to see if the breakpoint is to the left of the first offset.
+    if (entryPoints.length === 0) {
+      for (let script of scripts) {
+        let columnToOffsetMap = script
+          .getAllColumnOffsets()
+          .filter(({ lineNumber }) => {
+            return lineNumber === generatedLine;
+          });
+
+        if (columnToOffsetMap.length > 0) {
+          let { columnNumber: column, offset } = columnToOffsetMap[0];
+          if (generatedColumn < column) {
+            entryPoints.push({ script, offsets: [offset] });
+          }
+        }
+      }
     }
 
-    if (entryPoints.length === 0) {
-      return false;
-    }
     setBreakpointAtEntryPoints(actor, entryPoints);
     return true;
   }

devtools/server/tests/unit/test_setBreakpoint-at-the-beginning-of-a-line.js

@@ -0,0 +1,64 @@
+"use strict";
+
+var SOURCE_URL = getFileUrl("setBreakpoint-on-column.js");
+
+function run_test() {
+  return Task.spawn(function* () {
+    do_test_pending();
+
+    DebuggerServer.registerModule("xpcshell-test/testactors");
+    DebuggerServer.init(() => true);
+
+    let global = createTestGlobal("test");
+    DebuggerServer.addTestGlobal(global);
+
+    let client = new DebuggerClient(DebuggerServer.connectPipe());
+    yield connect(client);
+
+    let { tabs } = yield listTabs(client);
+    let tab = findTab(tabs, "test");
+    let [, tabClient] = yield attachTab(client, tab);
+    let [, threadClient] = yield attachThread(tabClient);
+    yield resume(threadClient);
+
+    let promise = waitForNewSource(threadClient, SOURCE_URL);
+    loadSubScript(SOURCE_URL, global);
+    let { source } = yield promise;
+    let sourceClient = threadClient.source(source);
+
+    let location = { line: 4, column: 2 };
+    let [packet, breakpointClient] = yield setBreakpoint(
+      sourceClient,
+      location
+    );
+
+    Assert.ok(!packet.isPending);
+    Assert.equal(false, "actualLocation" in packet);
+
+    packet = yield executeOnNextTickAndWaitForPause(function () {
+      Cu.evalInSandbox("f()", global);
+    }, client);
+
+    Assert.equal(packet.type, "paused");
+    let why = packet.why;
+    Assert.equal(why.type, "breakpoint");
+    Assert.equal(why.actors.length, 1);
+    Assert.equal(why.actors[0], breakpointClient.actor);
+
+    let frame = packet.frame;
+    let where = frame.where;
+    Assert.equal(where.source.actor, source.actor);
+    Assert.equal(where.line, location.line);
+    Assert.equal(where.column, 6);
+
+    let variables = frame.environment.bindings.variables;
+    Assert.equal(variables.a.value.type, "undefined");
+    Assert.equal(variables.b.value.type, "undefined");
+    Assert.equal(variables.c.value.type, "undefined");
+
+    yield resume(threadClient);
+    yield close(client);
+
+    do_test_finished();
+  });
+}

devtools/server/tests/unit/xpcshell.ini

@@ -222,6 +222,7 @@ reason = bug 937197
 [test_get-executable-lines-source-map.js]
 [test_xpcshell_debugging.js]
 support-files = xpcshell_debugging_script.js
+[test_setBreakpoint-at-the-beginning-of-a-line.js]
 [test_setBreakpoint-on-column.js]
 [test_setBreakpoint-on-column-in-gcd-script.js]
 [test_setBreakpoint-on-column-with-no-offsets-at-end-of-line.js]