Implement correct macros for liminf and limsup, fixes #111 (#887)

* Implement correct macros for liminf and limsup, fixes #111

* fix nits

test/__snapshots__/mathml-spec.js.snap

@@ -77,6 +77,76 @@ exports[`A MathML builder should make prime operators into <mo> nodes 1`] = `
 
 `;
 
+exports[`A MathML builder should output \\limsup_{x \\rightarrow \\infty} correctly in \\textstyle 1`] = `
+
+<math>
+  <semantics>
+    <mrow>
+      <msub>
+        <mo>
+          <mi mathvariant="normal">
+            lim sup
+          </mi>
+          <mo>
+            ⁡
+          </mo>
+        </mo>
+        <mrow>
+          <mi>
+            x
+          </mi>
+          <mo>
+            →
+          </mo>
+          <mi mathvariant="normal">
+            ∞
+          </mi>
+        </mrow>
+      </msub>
+    </mrow>
+    <annotation encoding="application/x-tex">
+      \\limsup_{x \\rightarrow \\infty}
+    </annotation>
+  </semantics>
+</math>
+
+`;
+
+exports[`A MathML builder should output \\limsup_{x \\rightarrow \\infty} in displaymode correctly 1`] = `
+
+<math>
+  <semantics>
+    <mrow>
+      <munder>
+        <mo>
+          <mi mathvariant="normal">
+            lim sup
+          </mi>
+          <mo>
+            ⁡
+          </mo>
+        </mo>
+        <mrow>
+          <mi>
+            x
+          </mi>
+          <mo>
+            →
+          </mo>
+          <mi mathvariant="normal">
+            ∞
+          </mi>
+        </mrow>
+      </munder>
+    </mrow>
+    <annotation encoding="application/x-tex">
+      \\limsup_{x \\rightarrow \\infty}
+    </annotation>
+  </semantics>
+</math>
+
+`;
+
 exports[`A MathML builder should render boldsymbol with the correct mathvariants 1`] = `
 
 <math>

test/katex-spec.js

@@ -2733,6 +2733,16 @@ describe("A macro expander", function() {
         expect("\\hspace{1em}").toParseLike("\\kern1em");
         expect("\\hspace*{1em}").toParseLike("\\kern1em");
     });
+
+    it("should expand \\limsup as expected", () => {
+        expect("\\limsup")
+            .toParseLike("\\mathop{\\operatorname{lim\\,sup}}\\limits");
+    });
+
+    it("should expand \\liminf as expected", () => {
+        expect("\\liminf")
+            .toParseLike("\\mathop{\\operatorname{lim\\,inf}}\\limits");
+    });
 });
 
 describe("A parser taking String objects", function() {

test/mathml-spec.js

@@ -51,6 +51,19 @@ describe("A MathML builder", function() {
         expect(getMathML("\\textstyle\\sum_a^b")).toMatchSnapshot();
     });
 
+    it("should output \\limsup_{x \\rightarrow \\infty} correctly in " +
+            "\\textstyle", () => {
+        const mathml = getMathML("\\limsup_{x \\rightarrow \\infty}");
+        expect(mathml).toMatchSnapshot();
+    });
+
+    it("should output \\limsup_{x \\rightarrow \\infty} in " +
+            "displaymode correctly", () => {
+        const settings = new Settings({displayMode: true});
+        const mathml = getMathML("\\limsup_{x \\rightarrow \\infty}", settings);
+        expect(mathml).toMatchSnapshot();
+    });
+
     it('should use <mpadded> for raisebox', () => {
         expect(getMathML("\\raisebox{0.25em}{b}")).toMatchSnapshot();
     });

test/screenshotter/ss_data.yaml

@@ -195,8 +195,11 @@ OperatorName: |
         \operatorname{Gam ma}(z) + \operatorname{\Gamma}(z) + \operatorname{}x
     \end{matrix}
 OpLimits: |
-    {\sin_2^2 \lim_2^2 \int_2^2 \sum_2^2}
-    {\displaystyle \lim_2^2 \int_2^2 \intop_2^2 \sum_2^2}
+    \begin{matrix}
+        {\sin_2^2 \lim_2^2 \int_2^2 \sum_2^2}
+        {\displaystyle \lim_2^2 \int_2^2 \intop_2^2 \sum_2^2} \\
+        \limsup_{x \rightarrow \infty} x \stackrel{?}= \liminf_{x \rightarrow \infty} x
+    \end{matrix}
 OverUnderline: x\underline{x}\underline{\underline{x}}\underline{x_{x_{x_x}}}\underline{x^{x^{x^x}}}\overline{x}\overline{x}\overline{x^{x^{x^x}}} \blue{\overline{\underline{x}}\underline{\overline{x}}}
 OverUnderset: |
     \begin{array}{l}