Avoid analyzing excluded language files for line counting

This change passes in a list of file types to the line counting
analysis. These are the languages for the databases being analyzed.
Line count analysis is restricted to these files.

src/count-loc.test.ts

@@ -0,0 +1,81 @@
+import * as path from "path";
+
+import test from "ava";
+
+import { countLoc } from "./count-loc";
+import { getRunnerLogger } from "./logging";
+import { setupTests } from "./testing-utils";
+
+setupTests(test);
+
+test("ensure lines of code works for cpp and js", async (t) => {
+  const results = await countLoc(
+    path.join(__dirname, "../tests/multi-language-repo"),
+    [],
+    [],
+    ["cpp", "js"],
+    getRunnerLogger(true)
+  );
+
+  t.deepEqual(results, {
+    cpp: 6,
+    js: 3,
+  });
+});
+
+test("ensure lines of code can handle undefined language", async (t) => {
+  const results = await countLoc(
+    path.join(__dirname, "../tests/multi-language-repo"),
+    [],
+    [],
+    ["rb", "py", "hucairz"],
+    getRunnerLogger(true)
+  );
+
+  t.deepEqual(results, {
+    rb: 6,
+    py: 5,
+  });
+});
+
+test("ensure lines of code can handle empty languages", async (t) => {
+  const results = await countLoc(
+    path.join(__dirname, "../tests/multi-language-repo"),
+    [],
+    [],
+    [],
+    getRunnerLogger(true)
+  );
+
+  t.deepEqual(results, {});
+});
+
+test("ensure lines of code can handle includes", async (t) => {
+  // note that "**" is always included. The includes are for extra
+  // directories outside the normal structure.
+  const results = await countLoc(
+    path.join(__dirname, "../tests/multi-language-repo"),
+    ["../../src/testdata"],
+    [],
+    ["js"],
+    getRunnerLogger(true)
+  );
+
+  t.deepEqual(results, {
+    js: 15,
+  });
+});
+
+test("ensure lines of code can handle exclude", async (t) => {
+  const results = await countLoc(
+    path.join(__dirname, "../tests/multi-language-repo"),
+    [],
+    ["**/*.py"],
+    ["rb", "py"],
+    getRunnerLogger(true)
+  );
+
+  t.deepEqual(results, {
+    rb: 6,
+  });
+});